JPH09167920A - Frequency conversion circuit provided with image rejection function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To cancel the both of the interference wave component by an image signal and the interference wave component by a half image signal and to simplify and miniaturize a circuitry. SOLUTION: Reception RF signals are distributed into three systems by distributors 1, 2 and 3, the local phase shift signals of the three systems having each π/2 relative phase difference are generated by distributors 5 and 6 and phase shifters 7 and 8 based on local oscillation signals, each of these reception RF signals and each local phase shift signal are multiplied by each of distributor 9, 10 and 11, and the output of the multiplier 9 and the output of a multiplier 10, and the output of the multiplier 10 and the output of the multiplier 11 are added in each of adders 16 and 17, respectively. After the π/2 relative phase difference is imparted to each added output by the phase shifter 18a and 19a, each added output is added by an adder 20, an intermediate frequency signal is outputted, and further, an inversion control is performed for the phase shift amount of the local phase shift signal supplied to the multiplier 10 by a control signal generation part 22 according to the high and low relation of a local oscillation frequency and a desired wave frequency.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a frequency conversion circuit provided in various wireless communication devices such as a car telephone device, a portable telephone device, and a cordless telephone device, and more particularly to an image rejection function for attenuating various image signal components. The present invention relates to a frequency conversion circuit including.

[0002]

2. Description of the Related Art In radio communication devices such as mobile communication devices, a heterodyne type receiver is generally adopted. In this type of receiver, a radio frequency (RF) signal received by an antenna is amplified by a high frequency amplifier, and then an intermediate frequency (IF: interm) is set by a frequency conversion circuit.
It is configured so that the IF signal is supplied to a demodulation circuit for demodulation. The frequency conversion is performed, for example, by mixing the RF signal with a reception local oscillation signal generated from a local oscillation circuit such as a frequency synthesizer.

In such a wireless communication device, when an image signal is received together with an RF signal by an antenna, the image signal is frequency-converted into an intermediate frequency band, which causes image interference. Here, the image signal is a signal existing at a position separated from the local oscillation frequency f _LO by the IF frequency f _{IF in} the direction opposite to the direction of the desired frequency, and the frequency thereof is f _LO −f _IF or f _LO. + F _IF
It is.

In order to prevent the interference due to the image signal, conventionally, for example, a band pass filter is arranged in front of the frequency conversion circuit to remove the image signal. However, this type of bandpass filter has a narrow band and requires a large amount of attenuation, so that the circuit scale becomes large, which leads to an increase in size and cost of the wireless communication device.

Therefore, recently, an attempt has been made to make the band pass filter unnecessary by providing a frequency conversion circuit with an image rejection function. FIG.
7 shows an example of the configuration of a conventional frequency conversion circuit having an image rejection function. In the figure, the RF signal is split into two by the distributor 102 and then input to the mixers 131 and 132, where it is mixed with a local oscillation signal having a phase difference of π / 2 to each other and I
It is converted to an F signal. The local oscillation signal is generated by dividing the oscillation output signal of the local oscillator 112 into two by the distributor 105 and then phase-shifting one of the two by −π / 2 by the phase shifter 120. The IF signals output from the mixers 131 and 132 are input to phase shifters 133 and 134, respectively, where they are phase-shifted by π / 4 and −π / 4, and then synthesized by the synthesizer 135 and output. .

In such a configuration, it is assumed that the frequency spectrum relationship is as shown in FIG. 48 (a). The RF signal is cos (ω _LO + ω _IF ) t (1-1) The image signal is cos (ω _LO −ω _IF ) t (1-2) The local oscillation signals input to the mixers 131 and 132 are each assumed to be a _{cosω LO t ... (1-3) sinω} LO t ... (1-4). Then, from the mixer 131, the above R
Cos .omega _IF t by F signal (1-1) with a local oscillator signal (1-3) ... and (1-5), cos .omega _IF by said image signal (1-2) with a local oscillator signal (1-3) An IF signal including t ... (1-6) is output.

On the other hand, the RF signal is output from the mixer 132.
(1-1) and local oscillation signal (1-4) −sinω _IF t… (1-7) and the above image signal (1-2) and local oscillation signal (1-4) sinω _IF t…. An IF signal including (1-8) is output.

Then, the IF signals (1-5) and (1-6) output from the mixer 131 are phase-shifted by π / 4 by the phase shifter 133, and cos (ω _IF t + π / 4), respectively. (1-9) cos (ω _IF t + π / 4) (1-10)

On the other hand, the I output from the mixer 132
The F signals (1-7) and (1-8) are phase-shifted by the phase shifter 134 by −π / 4, and −sin (ω _IF t−π / 4) = cos (ω _IF t + π / 4), respectively. _{... (1-11) sin (ω IF} t-π / 4) = - cos (ω IF t + π / 4) ... is (1-12).

Then, these phase-shifted IF signals (1-
9) and (1-11), and IF signals (1-10) and (1-12) are combined by the combiner 135, respectively, resulting in (1-9) + (1-11)
Is 2 cos ω _IF t (1-13), while (1-10) + (1-12) is 0. Therefore, the IF signal component due to the image signal (1-2) is canceled out, and as a result, only the IF signals (1-11) and (1-12) due to the RF signal are output from the output terminal.

However, the conventional frequency conversion circuit has the following problems. That is, the mixer 13
From 1,132, not only an image signal but also a half image signal is output. Half image signal is IF /
It is also called 2 image signal, and f _IF / 2 (f
It occurs at a position apart by _IF (intermediate frequency). The mixing output of the double harmonic of the half image signal and the double harmonic of the receiving local oscillation signal falls into the intermediate frequency band. This is because the relationship with the bandwidth B of the intermediate frequency is f _IF / 2
When <B, it becomes a problem. The reason is that when f _IF / 2 <B, the image signal exists within the band, so that it becomes impossible to suppress the image signal.

That is, the frequency spectrum is shown in FIG.
Assuming that the half image signal input in (a) is cos (ω _LO + ω _IF ) t (1-15), its second harmonic wave is {cos (ω _LO −ω _IF ) t} ² … (1 -16) Further, second harmonic of the reception local oscillation signal inputted to the mixer 31, 32 respectively become ^{_{(cosω LO t) 2 ... (}} 1-17) (sinω LO t) 2 ... (1-18).

Second harmonic of the half image signal (1-16)
The IF signal due to the second harmonic of the receiving local oscillation signal (1-17) becomes cosω _IF t ... (1-19), and the second harmonic of the half image signal (1-16) and the second harmonic of the receiving local oscillation signal IF signal due to the harmonic (1-18) is - cosω _IF t ... becomes (1-20). And these IF signals (1-19), (1-20)
When the phase shifters 133 and 134 respectively shift the phase, cos (ω _IF t + π / 4) (1-21) − cos (ω _IF t−π / 4) (1-22), and these IF signals When (1-21) and (1-22) are combined by the combiner 135,

[Equation 1]

## EQU1 ## As can be seen from this, the conventional frequency conversion circuit cannot cancel the interference due to the half image signal.

In the case of the frequency spectrum relationship shown in FIG. 48B, the phase shifters 133 and 13 shown in FIG.
By reversing the phase shift amount of 4, the relationship between the image signal and the half image signal can be similarly shown.

[0016]

As described above, the conventional frequency conversion circuit has a problem that the interference due to the image signal can be canceled but the interference due to the half image signal cannot be canceled.

The present invention has been made in view of the above circumstances, and a first object thereof is an image rejection function capable of canceling an interference wave component due to an image signal and an interference wave component due to a half image signal. It is to provide a frequency conversion circuit provided with.

A second object of the present invention is to provide a frequency conversion circuit having an image rejection function, which is suitable for integration and has a simple and compact circuit structure.

A third object is to provide a frequency conversion circuit having an image rejection function in which the number of multiplication circuits is reduced to further simplify the circuit structure.

A fourth object is that, even when the local oscillation signal frequency is higher or lower than the desired signal frequency, a common circuit is provided without preparing a dedicated circuit, and the interference wave component and the half wave due to the image signal are reduced. It is an object of the present invention to provide a frequency conversion circuit having an image rejection function capable of canceling interference wave components due to an image signal.

[0021]

In order to achieve the above first object, the present invention multiplies a received radio frequency signal by two local oscillation signals having a relative phase difference of π / 2, respectively. Two sets of mixers for synthesizing the multiplied outputs are provided, and one of the output signals of these mixers is phase-shifted by π / 4 and then the other is synthesized to output the output as an intermediate frequency signal.

Therefore, according to the present invention, the interference due to the half image signals is canceled in each of the two sets of mixers, and one of the output signals of these mixers is π / 4.
By interfering with the other output signal that is not phase-shifted after being phase-shifted, the interference due to the image signal is canceled. In other words, it is possible to cancel the interference caused by the image signal and the half image signal at the same time, and thus it is possible to obtain the intermediate frequency signal from which the image interference is removed.

On the other hand, in order to achieve the second object, according to the present invention, four-phase local oscillation signals having a relative phase difference of π / 2 are generated and the four-phase local oscillation signals are used as a reception radio frequency signal. Each of them is multiplied by a multiplication means or the received radio frequency signal is phase-shifted to generate a radio frequency signal of four phases having a relative phase difference of π / 2, and the radio frequency signals of these four phases are respectively oscillated locally. And the multiplication means, and among the four systems of multiplication outputs obtained by this multiplication means, between the multiplication outputs having a relative phase difference of π / 2, the phase shift means respectively produces π /
A relative phase difference of 2 is given, and the multiplication outputs to which the relative phase difference of π / 2 is given are added in the calculating means, and then the added outputs are mutually subtracted, and the subtracted output is output as an intermediate frequency signal. It was done like this.

Further, according to the present invention for achieving the second object, subtraction is performed between the multiplication outputs having the relative phase difference of π / 2 among the multiplication outputs of the four systems obtained by the multiplication means, A relative phase difference of π / 2 is given between the subtraction outputs, and then the subtraction outputs are combined with each other, and the combined output is output as an intermediate frequency signal.

Therefore, according to these inventions, the multiplication output of the four-phase local oscillation signal and the received radio high-frequency signal or the multiplication output of the four-phase reception radio high-frequency signal and the local oscillation signal is in the order of π / 2. A signal in which the image signal components have been canceled is obtained by adding each other after giving a phase difference, and by subtracting the addition outputs of these, the intermediate frequency signal of only the desired wave component in which the half image signal components have been canceled Is obtained. Also, the image signal component is canceled by subtracting each of the multiplication outputs having a relative phase difference of π / 2, and the subtraction output is given a relative phase difference of π / 2 and then subtracted to obtain a half image. An intermediate frequency signal having only the desired wave component in which the signal component is canceled is obtained.

That is, an intermediate frequency signal in which both the image signal component and the half image signal component are canceled can be obtained without using a narrow band image suppression filter.

Therefore, the narrow band image suppression filter can be dispensed with, so that the entire circuit can be constituted by the semiconductor element, and thus a circuit suitable for integration can be provided. Therefore, the circuit configuration can be simplified and miniaturized, and by this, it becomes possible to provide a further compact and lightweight mobile communication device.

In order to achieve the third object, the present invention distributes the received radio frequency signal to three systems and generates three local oscillation signals each having a phase difference of π / 2, and the above three systems are used. The received wireless high frequency signal and the above three local oscillation signals are multiplied by the first, second and third multiplication means, respectively. Then, the multiplication outputs of the first and second multiplication means and the multiplication outputs of the third and second multiplication means are respectively synthesized, and π is provided between the respective synthesized output signals.
After a phase difference of / 2 is applied, the combined output signals to which the phase difference is applied are combined and the combined output is output as an intermediate frequency signal.

Therefore, according to the present invention, it is of course possible to cancel the interference caused by the image signal and the half image signal at the same time, and the number of multiplying means can be reduced to three, so that the circuit configuration can be simplified and miniaturized accordingly. be able to.

In order to achieve the above-mentioned fourth object, the present invention relates to a phase shift combining means of an intermediate frequency stage for canceling an image signal component, in which π is provided between the combined output signals of the first and second combining means. As means for giving a phase difference of / 2, a phase shift means for selectively generating a predetermined first phase shift amount and a second phase shift amount having a polarity opposite to the first phase shift amount. Further, a phase shift control means is newly provided, and the phase shift control means shifts the phase shift combining means according to whether the frequency of the local oscillation signal is higher or lower than the frequency of the received radio frequency signal. The first and second phase shift amounts generated by the phase means are switched and controlled.

In the phase shift synthesizing means, an adding means and a subtracting means are provided as means for synthesizing the respective synthetic output signals given a phase difference of π / 2, and a synthetic control means is newly provided. The combining control means selectively switches between the adding means and the subtracting means of the phase shift combining means depending on whether the frequency of the local oscillation signal is higher or lower than the frequency of the received radio frequency signal. .

Further, in the local oscillation signal generating means,
As means for generating a local oscillation signal of four phases or three phases each having a phase difference of π / 2, a predetermined third phase shift amount and a fourth phase having a polarity opposite to the third phase shift amount. The phase shift means for selectively generating the phase shift amount and the phase shift control means are newly provided, and by this phase shift control means,
The third and fourth phase shift amounts generated by the phase shift means of the local oscillation signal generation means are switched and controlled depending on whether the frequency of the local oscillation signal is higher or lower than the frequency of the received radio frequency signal. It is a thing.

With this configuration, regardless of whether the local oscillation signal frequency is higher or lower than the desired signal frequency, there is no need to prepare a dedicated circuit for the local oscillation signal frequency, and a common circuit can be used to generate the interference wave component and the interference wave component due to the image signal. It is possible to cancel the interfering wave components due to the half image signal. Therefore, the circuit configuration can be further simplified and downsized.

[0034]

BEST MODE FOR CARRYING OUT THE INVENTION

[First Embodiment] FIG. 1 shows a first frequency conversion circuit having an image rejection function according to the present invention.
It is a circuit block diagram showing an embodiment of.

This frequency conversion circuit has first and second mixer circuits 11a and 12a. These mixer circuits 11a and 12a are input from an RF signal input terminal 101 and then distributed by a distributor 102. RF received in two branches
A signal is input.

The first mixer circuit 11a further divides the received RF signal, which has been branched and input, into two by the distributor 103, and inputs the branched RF signals to the multipliers 108 and 109.
8 and 109 mix with two local oscillation signals each having a mutual phase difference of π / 2, and the output signal is mixed by the combiner 11
It is configured to output the IF signal by mutually adding in 3. Here, the two local oscillation signals are
The local oscillation signal generated from the local oscillator 112 is branched into two by the distributor 105, and one of the two is branched by the distributor 10.
It is further bifurcated at 6 and each branch output is + π /
It is generated by phase shifting by the 4-phase shifter 118 and the −π / 4 phase shifter 119.

On the other hand, in the second mixer circuit 12a, the RF signal branched and input from the distributor 102 is further branched into two by the distributor 104 and input to the multipliers 110 and 111. The IF signal is output by mixing with two local oscillation signals each having a mutual phase difference of π / 2 and adding the output signals to each other by the combiner 114. Here, the above-mentioned two local oscillation signals are obtained by dividing the local oscillation signal generated from the local oscillator 112 into two by the distributor 105, and further dividing the other of them into two by the distributor 107, out of the respective branched outputs. It is generated by shifting one of the phases by the -π / 2 phase shifter 120.

The IF signal output from the first mixer circuit 11a is phase-shifted by -π / 4 by the -π / 4 phase shifter 121 and then input to the subtractor 115. The difference from the IF signal output from the second mixer circuit 12a is calculated. Then, the IF signal after the subtraction is passed through the IF band pass filter 116 and then supplied from the IF signal output terminal 117 to a demodulation circuit (not shown) or the like.

Next, the operation of rejecting the image signal by the circuit configured as described above will be described. First, the rejection operation of the half image signal will be described. The half image signal included in the input RF signal is cos (ω _LO + ω _IF / 2) t (1-24) The local oscillation output input to the first multiplier 8 is cos (ω _LO t + π / 4). (1-25) Second, the local oscillation output input to the multiplier 9 is cos (ω _LO t−π / 4) (1-26) The local oscillation output input to the third multiplier 10 is cos ω _LO t (1-27) The local oscillation output input to the fourth multiplier 11 is sin ω _IF t (1-28).

Here, the interference due to the half image signal is
As described above, the doubled wave of the input RF signal and the doubled wave of the local oscillation output are mixed and fall into the IF band. Therefore, the output of the multiplier 108 is (1-24) ² × ( 1-25) ² = −sin ω _IF t (1-29) The output of the second multiplier 109 is (1-24) ² × (1-26) ² = −sin ω _IF t (1-30) ) The output of the third multiplier 110 is (1-24) ² × (1-27) ² = cos ω _IF t (1-31) The output of the fourth multiplier 111 is (1-24) ² × (1-28) ² = −cos ω _IF t (1−32), so that the IF signal synthesis outputs of the synthesizers 113 and 114 are (1-29) + (1-30) = 0 (1- 31) + (1-32) = 0 and the half image signals are canceled.

Next, the image signal rejection operation will be described. The input RF signal is cos (ω _LO + ω _IF ) t (1-33) The input image signal is cos (ω _LO −ω _IF ) t (1-34) Local input to each multiplier 108-111 The oscillation output is
These are (1-25) to (1-28) respectively.

In the output signal of the multiplier 108, the R
The signal corresponding to the F signal and the signal corresponding to the image signal are represented by cos (ω _IF t-π / 4) (1-35) cos (ω _IF t + π / 4) (1-36), respectively. In the output signal of the multiplier 109, R
Each signal corresponding to the signal and the image signal corresponding to the F signal is represented by _{cos (ω IF t + π /} 4) ... (1-37) cos (ω IF t-π / 4) ... (1-38).

In the output signal of the multiplier 110,
Signal corresponding to the signal and the image signal corresponding to the RF signal are respectively represented by _{cosω IF t ... (1-39) cosω} IF t ... (1-40), the output signal of the multiplier 111, the R
The signal corresponding to the F signal and the signal corresponding to the image signal are respectively represented by −sin ω _IF t ... (1-41) sin ω _IF t ... (1-42).

Then, the output signal of the multiplier 108 and the output signal of the multiplier 109 are combined by the combiner 113 and then the signal obtained by -π / 4 phase shift by the -π / 4 phase shifter 121 and the multiplier 110. Of the IF band pass filter 1 is input to the subtractor 115, and the subtracter 115 subtracts the signal obtained by combining the output signal of
When passed through a 16, IF signal 2 sin .omega _IF t becomes corresponding to the received F signal, the signal corresponding to the image signal becomes zero. That is, the image signals are canceled.

As described above, according to the first embodiment, it is possible to cancel the interference caused by the image signal and the interference caused by the half image signal. Also, the subtractor 11
By disposing the IF band pass filter 116 for removing the harmonic component on the output side of 5, it is possible to reduce the number of IF band pass filters to one. This configuration is convenient when the circuit is integrated, and thus contributes to further simplification of the circuit configuration.

In the above description, the case of the frequency spectrum relationship shown in FIG. 48 (a) has been described as an example. However, in the case of the frequency spectrum relationship shown in FIG. 48 (b), -π / 4 shift is made. Both the image signal interference and the half image interference can be canceled by simply replacing the phase shifter 121 with a + π / 4 phase shifter.

The embodiment described above can be modified in various ways as follows. (First Modification) FIG. 2 is a circuit block diagram showing the configuration of a frequency conversion circuit according to the first modification, and the same parts as those in FIG. 1 are designated by the same reference numerals.

In the circuit shown in FIG. 2, in order to remove the harmonic components contained in the IF output signal, the multipliers 108 to 111 and the combiners 113 and 114 of the first and second mixer circuits 11a and 12a, respectively. And band-pass filters 141 to 144 are respectively disposed between and. With this configuration, the reactor wave characteristic for removing the harmonic component can be set according to the frequency characteristic of each of the multiplication outputs of the multipliers 108 to 111, so that the subtraction as shown in FIG. 1 is performed. Bowl 1
As compared with the case where the IF band pass filter 116 is provided on the output side of 15, harmonic components can be removed more reliably.

(Second Modification) FIG. 3 is a circuit block diagram showing the structure of a frequency conversion circuit according to a second modification of the first embodiment. The same parts as those in FIG. Is attached.

In the circuit shown in FIG. 3, the second mixer circuit 1
A + π / 4 phase shifter 145 is arranged between the second synthesizer 114 and the subtractor 115. With this configuration, it is possible to cancel the interference due to the image signal as in the case of the configuration shown in FIG.

(Third Modification) FIG. 4 is a circuit block diagram showing the structure of a frequency conversion circuit according to a third modification of the first embodiment. The same parts as those in FIG. Is attached.

In the circuit shown in FIG. 4, the second mixer circuit 1
2, the + π / 2 phase shifter 146 is used to generate the local oscillation signal for mixing, and the synthesizer 113 and the subtractor 115 of the first mixer circuit 11 are correspondingly generated.
A + π / 4 phase shifter 145 is arranged between the and to cancel the interference due to the image signal. Also by this, it is possible to cancel the interference due to the image signal as in the configuration of FIG.

(Fourth Modification) FIG. 5 is a circuit block diagram showing a configuration of a frequency conversion circuit according to a fourth modification of the first embodiment. The same parts as those in FIG. Is attached.

In the circuit shown in FIG. 5, the second mixer circuit 1
2, the + π / 2 phase shifter 146 is used to generate a local oscillation signal for mixing, and the synthesizer 114 and the subtractor 115 of the second mixer circuit 12 are correspondingly generated.
A −π / 4 phase shifter 121 is arranged between the input and the output to cancel the interference due to the image signal. Also by this, it is possible to cancel the interference due to the image signal as in the configuration of FIG.

(Other Modifications) Incidentally, FIG.
The configurations of the modified examples of FIG. 5 correspond to the case of having the relationship of the frequency spectrum shown in FIG. In the configurations of FIGS. 2 to 5, when the frequency spectrum relationship shown in FIG. 48B is applied, the polarity of the phase shift amount of the phase shifter of the IF signal may be inverted.

Further, the phase shifter for generating the local oscillation signal is replaced between the input distributors 103 and 104 of the first and second mixer circuits 11 and 12 and the respective multipliers 108 to 111. May be. Even with this configuration,
Interference due to image signal The interference due to the half image signal can be canceled.

[Second Embodiment] In this embodiment,
This is when the local oscillation frequency is lower than the desired wave frequency (local lower). FIG. 6 is a circuit block diagram showing the configuration of the frequency conversion circuit according to this embodiment.

In the figure, the received RF signal is RF
After being input from the input terminal 201 and divided into two by the distribution circuit 204, a single balanced mixer (hereinafter referred to as S
BM) and input to the multipliers 211 and 212. On the other hand, the local oscillation signal generated by the local oscillation circuit 203 is divided into two by the distribution circuit 205, one of which is + π /
The 4-phase shift circuit 223 shifts the phase by + π / 4, and the other phase shifts the phase by −π / 4 shift circuit 224 by −π / 4. +
The π / 4 phase-shifted local oscillation signal is converted by the differential output circuit 221 into a phase of + π / 4 and an opposite phase of −3π / 4, and is input to the SBM 211. On the other hand, the local oscillation signal phase-shifted by -π / 4 is -π / by the differential output circuit 222.
4 and its opposite phase + 3π / 4 phase is converted to SBM2
12 is input.

In the SBMs 211 and 212, the desired wave (f _LO + f _IF ) of the received signal and the image signal (f _LO + f _IF ) are received.
Is multiplied by the local oscillation signal (f _LO ) and the second harmonic of the half image signal (2f _LO + f _IF ) is multiplied by the second harmonic of the local oscillation signal (2f _LO ). At this time SBM2
The output signal of the IF frequency band of 11 is the output multiplied by + π / 4 phase-shifted local oscillation signal is {cos (ω _LO t + ω _IF t) + cos (ω _LO t−ω _IF t)} × cos (ω _LO t + π / 4) + cos ² (ω _LO t + 1 / 2ω _IF t) × cos ² (ω _LO t + π / 4) = 1/2 {cos (ω _IF t−π / 4) + cos (ω _IF t + π / 4) +1 _{/ 4 (ω IF t-π} / 2)} ... a (2-1). The vector at this time is shown in FIG.

Where cos (ω _LO t + ω _IF t) is the desired wave,
cos (ω _LO t−ω _IF t) is an image signal, cos ² (ω _LO t
+ Π / 4) is the local oscillation signal, cos (ω _IF t−π / 4) is the second harmonic of the half image signal, and cos ² (ω _LO t + π /
4) represents the second harmonic of the local oscillation frequency,
Also, cos (ω _IF t−π / 4) is the desired wave component, and cos (ω _IF t +
π / 4) is the image signal component, 1/4 (ω _IF t-π /
2) respectively represent the half image signal components.

Further, the multiplication output with the local oscillation signal phase-shifted by -3π / 4 is {cos (ω _LO t + ω _IF t) + cos (ω _LO t−ω _IF t)} × cos (ω _LO t−3π / 4) + cos ² (ω _LO t + 1 / 2ω _IF t) × cos ² (ω _LO t−3π / 4) = 1/2 {cos (ω _IF t + 3π / 4) + cos (ω _IF t−3π / 4) +1 _{/ 4 (ω IF t -π /} 2)} ... is (2-2). The vector at this time is shown in FIG.

Where cos (ω _LO t + ω _IF t) is the desired wave,
cos (ω _LO t−ω _IF t) is an image signal, cos (ω _LO t−3
π / 4) is the local oscillation signal, cos ² (ω _LO t + 1 / 2ω _IF
t) is the second harmonic of the half image signal, cos ² (ω _LO
t−3π / 4) represents the second harmonic of the local oscillation signal, and cos (ω _IF t + 3π / 4) is the desired wave component,
cos (ω _IF t-3π / 4) is the image signal component, 1/4
(Ω _IF t-π / 2) represents each 1/2 image signal component.

On the other hand, in the output signal in the IF frequency band of the SBM 212, the multiplication output with the local oscillation signal phase-shifted by -π / 4 is {cos (ω _LO t + ω _IF t) + cos (ω _LO t−ω _IF t) } × cos (ω _LO t−π / 4) + cos ² (ω _LO t + 1 / 2ω _IF t) × cos ² (ω _LO t−π / 4) = 1/2 {cos (ω _IF t + π / 4) + cos (ω _IF t−π / 4) +1/4 cos (ω _IF t + π / 2)} (2-3) The vector at this time is shown in FIG.

Where cos (ω _LO t + ω _IF t) is the desired wave,
cos (ω _LO t−ω _IF t) is the image signal, cos (ω _LO t−π
/ 4) is the local oscillation signal, cos ² (ω _LO t + 1 / 2ω
_IF t) is the second harmonic of the half image signal, cos ² (ω
_LO t−π / 4) represents the second harmonic of the local oscillation signal, and cos (ω _IF t + π / 4) is the desired wave component, co
s (ω _IF t−π / 4) is the image signal component, 1/4 cos (ω
_IF t + π / 2) represents a half image signal component.

The multiplication output with the local oscillation signal phase-shifted by + 3π / 4 is: {cos (ω _LO t + ω _IF t) + cos (ω _LO t−ω _IF t)} × cos (ω _LO t + 3π / 4) + cos ² (ω _LO t + 1 / 2ω _IF t) × cos ² (ω _LO t + 3π / 4) = 1/2 {cos (ω _IF t−3π / 4) + cos (ω _IF t−3π / 4) +1/4 cos ( ω _IF t + π / 2)} (2-4). The vector at this time is shown in FIG.

Where cos (ω _LO t + ω _IF t) is the desired wave,
cos (ω _LO t−ω _IF t) is an image signal, cos (ω _LO t + 3
π / 4) is the local oscillation signal, cos ² (ω _LO t + 1 / 2ω _IF
t) is the second harmonic of the half image signal, cos ² (ω _LO
t + 3π / 4) represents the second harmonic of the local oscillation signal, and cos (ω _IF t−3π / 4) is the desired wave component,
cos (ω _IF t-3π / 4) is the image signal component, 1 / 4co
s (ω _IF t + π / 2) represents each half image signal component.

The multiplication outputs (1-1) and (1-2) are respectively
The phase is shifted by + π / 4 by the + π / 4 phase shift circuit 231 and becomes as follows. _{1/2 {cos (ω IF t)} + cos (ω IF t + π / 2) + 1 / 4cos (ω IF t-π / 4)} ... (2-1) '1/2 {cos (ω IF t + π) + cos ( ω _IF t−π / 2) +1/4 cos (ω _IF t−π / 4)} (2-2) ′ The vectors at this time are shown in FIGS. 12 (a) and 12 (b).

On the other hand, the multiplication outputs (2-3) and (2-4) are respectively shifted by -π / 4 by the -π / 4 phase shift circuit 132 to become as follows. 1/2 {cos (ω _IF t) + cos (ω _IF t−π / 2) +1/4 cos (ω _IF t + π / 4)} (2-3) ′ 1/2 {cos (ω _IF t−π) + Cos (ω _IF t + π / 2) +1/4 cos (ω _IF t + π / 4)} (2-4) ′ The vectors at this time are shown in FIGS. 12 (c) and 12 (d).

Of the phase shift outputs (2-1) 'to (2-4)', (2-1) 'and (2-3)' are input to the adder circuit 241 and added to each other,

(Equation 2)

Is obtained. Further, (2-2) 'and (2-4)' are input to the adder circuit 242 and added to each other,

(Equation 3)

Is obtained. FIGS. 13 (a) and 13 (b) show the vectors of these addition outputs (2-5) and (2-6), respectively.

The addition outputs (2-5) and (2-6) obtained by the respective addition circuits 241 and 242 are input to the subtraction circuit 243, where (2-6) is subtracted from (2-6). To be done. As a result,
2cos (ω _IF t) is output from the subtraction circuit 243, and the subtraction output has the high frequency component removed by the bandpass filter 206 to become only the desired wave signal component, which is the IF output terminal as the IF signal after frequency conversion. It is output from 202.

As described above, in the second embodiment, the multiplication signals 211 and 212 multiply the received signal and the local oscillation signal that is phase-shifted into four signals each having a phase difference of π / 2, and the multiplication outputs are multiplied. Phase shift circuit 23 having a relatively different π / 2 phase
1,232 phase shift. Then, the phase shift outputs are mutually added by the adder circuits 241 and 242, and then further subtracted.

Therefore, the two adder circuits 241 and 24
Two signals in which the image signal component is canceled are obtained from 2, and the half image component is suppressed by subtracting these two signals, and only the desired wave is obtained.
An F signal is obtained. That is, both the image signal component and the half image signal component can be suppressed. Further, since the narrow band filter is not required, the entire circuit can be composed of semiconductor elements, which enables the integrated circuit.

When the local oscillation signal generating circuit 220 generates four-phase local oscillation signals having a relative phase difference of π / 4, the differential output circuits 221 and 222 are used to generate π.
Since two local oscillation signals having a relative phase difference of / 2 are generated, the number of distributors can be reduced and the circuit configuration can be simplified and miniaturized accordingly.

In the second embodiment described above,
The following various modifications are possible. (First Modification) FIG. 7 is a circuit block diagram showing a configuration of a frequency conversion circuit according to the first modification. The same parts as those in FIG. 6 are designated by the same reference numerals and detailed description thereof will be omitted. .

In the circuit shown in FIG. 7, the multiplication output of the multiplication circuit 241 is phase-shifted by the -π / 4 phase shift circuit 232.
The multiplication output of the multiplication circuit 242 is phase-shifted by the + π / 4 phase shift circuit 231. Then, the phase shift outputs are subtracted by the subtraction circuits 251 and 252, and then the subtraction output is further subtracted by the subtraction circuit 243, so that both the image signal component and the half image signal component are suppressed.
I'm trying to get a signal.

(Second Modification) FIG. 8 is a circuit block diagram showing a configuration of a frequency conversion circuit according to the second modification. The same parts as those in FIG. Is omitted.

In the circuit shown in FIG. 8, similarly to the circuit shown in FIG. 6, the multiplication outputs of the multiplication circuits 241 and 242 are respectively +.
The π / 4 phase shift circuit 231 and the −π / 4 phase shift circuit 232 perform phase shift, and the phase shift outputs are subtracted by the subtraction circuits 251 and 252 as in the circuit shown in FIG. The subtraction circuit 243 is configured to perform further subtraction.

(Third Modification) FIGS. 9 and 49 are circuit block diagrams showing the structure of a frequency conversion circuit according to the third modification, in which the same portions as those in FIGS. 6 and 7 are the same. The reference numerals are given and detailed description is omitted.

In the circuit shown in FIG. 9, as in the circuit shown in FIG. 7, the multiplication outputs of the multiplication circuits 241 and 242 are respectively-.
The π / 4 phase shift circuit 232 and the + π / 4 phase shift circuit 231 perform phase shift, and the phase shift outputs are subtracted by the adder circuits 241 and 242 as in the circuit shown in FIG. The subtraction circuit 243 is configured to perform further subtraction. Also with this configuration, the same effect as that of the configuration shown in FIG. 6 can be obtained.

In each of the modified examples described above, when the local oscillation frequency is lower than the desired wave frequency (local lower)
However, the present invention can be similarly applied to the case where the local oscillation frequency is higher than the desired wave frequency (local upper). FIG. 49 shows an example of the circuit configuration in this case. In this circuit, contrary to the circuit shown in FIG. 9, the + side phase shift output of the + π / 4 phase shift circuit 231 is input to the adder circuit 241, and the − side phase shift output is added to the adder circuit 2.
42 has been input. In this way, the adder circuits 241, 2
By inverting the polarity of the phase shift output input to 42, it is possible to cope with the case of the local upper.

(Fourth Modification) In each of the modifications described above, the local oscillation signal is phase-shifted to generate four local oscillation signals having phase shifts of π / 2 different from each other. The reception RF signal is multiplied by the multiplication circuits 211 and 212. However, the reception RF signal is phase-shifted and phase-shifted by π /.
Generate four reception RF signals that differ from each other by two
The F signal and the local oscillation signal may be configured to be multiplied by the multiplication circuit.

FIG. 10 is a circuit block diagram showing the fourth modification, in which the same parts as those in FIG. 6 are designated by the same reference numerals. In the figure, an RF signal received by an antenna (not shown) is input to the reception RF signal phase shift circuit 270,
In this circuit 270, the signal is divided into two by the distribution circuit 204, and then is divided into + π / 4 phase shift circuit 273 and −π / 4 phase shift circuit 2
74 respectively. Then, the received RF signal phase-shifted by + π / 4 by the + π / 4 phase-shift circuit 273 is
In the differential output circuit 271, + π / 4 and the opposite phase of −3π
After being converted to a / 4 phase, it is input to the SBM 261 and mixed.

On the other hand, the -π / 4 phase shift circuit 274 causes -π.
The / 4 phase-shifted reception RF signal is converted by the differential output circuit 272 into a phase of −π / 4 and its opposite phase of + 3π / 4, and then input to the SBM 262 for mixing. The circuit configuration of the multiplication circuits 261 and 262 and thereafter is shown in FIG.
Are the same as those shown in FIG.

Even with such a circuit configuration, as shown in FIG.
Similar to the case shown in, it is possible to suppress both the image signal component and the half image signal component and to eliminate the need for a narrow band filter. You can

In addition, the + π / 4 phase shift circuit is used as a 0 phase shift circuit and a −π / 2 phase shift circuit, and the −π / 4 phase shift circuit is + π.
It is also possible to replace them with a / 2 phase shift circuit and a 0 phase shift circuit.

[Third Embodiment] In this embodiment,
This is a further improvement of the second embodiment, in which subtraction means is provided between the multiplication means for multiplying the received radio frequency signal and the local oscillation signal and the phase shift means for shifting the multiplication output. Then, the subtraction means subtracts the multiplication outputs having the relative phase difference of π / 2 from each other, and the outputs are phase-shifted by the phase-shifting means and then added by the adding means, whereby the image signal component and the half image signal component are obtained. The canceled reception intermediate frequency signal is obtained.

FIG. 14 is a circuit block diagram showing a first example of the configuration. In the figure, the same parts as those in FIG. 6 are designated by the same reference numerals, and detailed description thereof will be omitted. Subtracting circuits 281 and 282 are respectively inserted between the multiplying circuits 211 and 212 formed of a single balanced mixer (SBM) and the + π / 4 phase shifting circuits 231 and 232. These subtraction circuits 281 and 282 are for canceling the half image signal components, and are between the multiplication outputs B11 and B12 and B13 and B14 having the relative phase difference of π / 2 output from the multiplication circuits 211 and 212, respectively. Then, the subtraction outputs C11 and C12 are supplied to the + π / 4 phase shift circuit 231 and the −π / 4 phase shift circuit 232.

The + π / 4 phase shift circuit 231 and the −π / 4 phase shift circuit 232 respectively add the subtraction outputs C11 and C12 to +.
By π / 4 and −π / 4 phase shift, the relative π
The subtraction outputs D11 and D12 having a phase difference of / 2 are output, and these subtraction outputs D11 and D12 are input to the adder circuit 291. The adder circuit 291 outputs the subtraction outputs D11 and D.
The image signal component is canceled by adding 12 signals, and the addition output E11 is output from the IF output terminal 202 as an intermediate frequency signal after passing through the IF bandpass filter 206.

With this configuration, first, in the local oscillation signal generation circuit 220, the local oscillation signal A phase-shifted from the differential output circuit 221 by + π / 4 and −3π / 4 is generated.
11 and A12 are output, and a local oscillation signal A is phase-shifted from the differential output circuit 222 by −π / 4 and + 3π / 4.
13 and A14 are output. Then, these local oscillation signals A11, A12 and A13, A14 and the received RF signal are respectively multiplied by multiplication circuits 211 and 212, whereby multiplication outputs B11 and B12 are down-converted to an intermediate frequency band.
And B13 and B14 are output.

At this time, the multiplication outputs B11, B12 and B13, B14 are expressed as follows. B11 = {cos (ω _LO t + ω _IF t) + cos (ω _LO t−ω _IF t)} × cos (ω _LO t + π / 4) + cos ² (ω _LO t + 1 / 2ω _IF t) × cos ² (ω _LO t + π / 4) = 1/2 {cos (ω _IF t-π / 4) + cos (2ω _LO t + ω _IF t + π / 4) + cos (ω _IF t + π / 4) + cos (2ω _LO t−ω _IF t + π / 4)} + 1 / 4 {1/2 cos (ω _IF t −π / 2) +1/2 cos (4ω _LO t + ω _IF t + π / 2) + cos (2ω _LO t + ω _IF t) + cos (2ω _LO t + π / 2) +1} (3-1 ) B12 = {cos (ω _LO t + ω _IF t) + cos (ω _LO t−ω _IF t)} × cos (ω _LO t−3π / 4) + cos ² (ω _LO t + 1 / 2ω _IF t) × cos ² ( ω _LO t−3π / 4) = 1/2 {cos (ω _IF t + 3π / 4) + cos (2ω _LO t + ω _IF t-3π / 4) + cos (ω _IF t−3π / 4) + cos (2ω _LO t−ω _IF t-3π / 4)} + 1/4 {1/2 cos (ω _IF t-π / 2) +1/2 cos (4ω _LO t + ω _IF t + π / 2) + cos (2ω _LO t + ω _IF t) + cos (2ω _LO t + π / 2) +1} (3-2) B13 = {cos (ω _LO t + ω _IF t) + cos (ω _LO t−ω _IF t )} × cos (ω _LO t−π / 4) + cos ² (ω _LO t + 1 / 2ω _IF t) × cos ² (ω _LO t−π / 4) = 1/2 {cos (ω _IF t + π / 4) + Cos (2ω _LO t + ω _IF t−π / 4) + cos (ω _IF t−π / 4) + cos (2ω _LO t−ω _IF t−π / 4)} + 1/4 {1 / 2cos (ω _IF t + π / 2) +1/2 cos (4ω _LO t + ω _IF t−π / 2) + cos (2ω _LO t + ω _IF t) + cos (2ω _LO t−π / 2) +1} (3-3) B14 = {cos (ω _LO t + ω _IF t) + cos (ω _LO t−ω _IF t)} × cos (ω _LO t + 3π / 4) + cos ² (ω _LO t + 1 / 2ω _IF t) × cos ² (ω _LO t + 3π / 4) = 1/2 { _{cos (ω IF t-3π /} 4) + cos (2ω LO t + ω IF t + 3π / 4) + cos (ω IF t + 3π / 4) + cos (2ω LO t-ω IF + 3π / 4)} + 1/4 {1 / 2co s (ω IF t + π / 2) + 1 / 2cos (4ω LO t + ω IF t-π / 2) + cos (2ω LO t + ω IF t) + cos (2ω LO t-π / 2) +1} (3-4) Next, the above-mentioned multiplication outputs B11, B12 and B13, B14 are
In the subtraction circuits 281, 282, the multiplication output B
Subtraction is performed between 11, B12 and the multiplication outputs B13, B14. The subtracted outputs C11 and C12 are represented as follows.

C11 = cos (ω _IF t−π / 4) + cos (2ω _LO t + ω _IF t + π / 4) + cos (ω _IF t + π / 4) + cos (2ω _LO t−ω _IF t + π / 4) (3-5) ) C12 = cos (ω _IF t + π / 4) + cos (2ω _LO t + ω _IF t−π / 4) + cos (ω _IF t−π / 4) + cos (2ω _LO t−ω _IF t−π / 4) (3 -6) As is apparent from the equation, the signal component generated by the multiplication of the second harmonic of the half image signal and the second harmonic of the local oscillation signal is canceled in the in-phase subtraction.

Further, the subtraction outputs C11 and C12 of the subtraction circuits 281 and 282 are + π / 4 phase shift circuit 231 respectively.
And -π / 4 phase shift circuit 232, where they are + π / 4 and -π / 4 phase-shifted, respectively, in order to give a relative phase difference of π / 2 between the subtracted outputs C11 and C12. The phase shift signal outputs D11 and D12 are expressed as follows.

D11 = cos (ω _IF t) + cos (2ω _LO t + ω _IF t + π / 2) + cos (ω _IF t + π / 2) + cos (2ω _LO t−ω _IF t + π / 2) (3-7) D12 = cos (ω _IF t) + cos (2ω _LO t + ω _IF t−π / 2) + cos (ω _IF t−π / 2) + cos (2ω _LO t−ω _IF t−π / 2) (3-8) and , The phase shift signal outputs D11 and D12 are added by the adder circuit 2
At 91, they are added and synthesized with each other. The added synthetic signal E11 is expressed as follows. _{E11 = 2cos (ω IF t)} ... (3-9) In other words, by the + [pi / 4 and - [pi] / 4 phase shift in each phase shift circuit 231 and 232, the subtraction output D11, D
As shown in 12, the desired signal component has the same phase and the image signal component has the opposite phase. Therefore, the phase shift signal outputs D11, D
When 12 is added and synthesized by the addition circuit 291, the desired signal component cos (ω _IF t) is not canceled, and the image signal components cos (ω _IF t + π / 2) and cos (ω _IF t−π / 2) are canceled. Will be.

The summed composite signal E11 in which the image signal components have been canceled has the signals outside the IF band removed by the IF band pass filter 206, and then only the desired signal component is demodulated from the IF signal output terminal 202 in the subsequent stage, for example, demodulation. Output to the circuit.

As described above, according to this embodiment, both the image signal component and the half image signal component can be suppressed as in the second embodiment.
Furthermore, the narrow band filter is not required, and the entire circuit can be composed of semiconductor elements, which enables integration into an integrated circuit. Further, when the local oscillation signal generation circuit 220 generates four-phase local oscillation signals having a relative phase difference of π / 4, the differential output circuits 221 and 222 are used to generate π.
Since two local oscillation signals having a relative phase difference of / 2 are generated, it is possible to reduce the number of distributors and simplify the circuit configuration.

Incidentally, in the above-mentioned third embodiment,
The following various modifications are possible. (First Modification) First, in the circuit configuration shown in FIG. 14, when the local oscillation frequency is lower than the desired wave frequency (local
However, the present invention can be similarly applied to the case where the local oscillation frequency is higher than the desired wave frequency (local upper).

FIG. 15 is a circuit block diagram showing an example of the configuration in the case of the local upper, and the same functional portions as those in FIG. 14 are designated by the same reference numerals. In the figure, the subtraction output C21 of the subtraction circuit 281 is phase-shifted by the -π / 4 phase shift circuit 232 and then input to the addition circuit 291, while the subtraction output C22 of the subtraction circuit 282 is + π / 4 phase shift circuit 2
After being phase-shifted at 31, it is input to the adder circuit 291.

In such a configuration, first, in the local oscillation signal generation circuit 220, the local oscillation signal A2 phase-shifted from the differential output circuit 221 by + π / 4 and −3π / 4 is generated.
1 and A22 are output, and a local oscillation signal A is phase-shifted by -π / 4 and + 3π / 4 from the differential output circuit 222.
23 and A24 are output. Then, these local oscillation signals A21, A22 and A23, A24 are multiplied by the received RF signal in the multiplication circuits 211 and 212, respectively, whereby the multiplication outputs B21 and B22 are down-converted to the intermediate frequency band.
And B23 and B24 are output.

At this time, the multiplication outputs B21, B22 and B23, B24 are expressed as follows, respectively. B21 = {cos (ω _LO t−ω _IF t) + cos (ω _LO t + ω _IF t)} × cos (ω _LO t + π / 4) + cos ² (ω _LO t−1 / 2ω _IF t) × cos ² (ω _LO t + π / 4) = 1/2 {cos (ω _IF t + π / 4) + cos (2ω _LO t−ω _IF t + π / 4) + cos (ω _IF t−π / 4) + cos (2ω _LO t + ω _IF t + π / 4) } +1/4 {1/2 cos (ω _IF t + π / 2) +1/2 cos (4ω _LO t−ω _IF t + π / 2) + cos (2ω _LO t−ω _IF t) + cos (2ω _LO t + π / 2) +1} (3-11) B22 = {cos (ω _LO t−ω _IF t) + cos (ω _LO t + ω _IF t)} × cos (ω _LO t−3π / 4) + cos ² (ω _LO t−1 / 2ω _IF t) × cos ² (ω _LO t−3π / 4) = 1/2 {cos (ω _IF t−3π / 4) + cos (2ω _LO t−ω _IF t−3π / 4) + cos (ω _IF t + 3π / 4) + cos (2ω _LO t + ω _IF t−3π / 4)} + 1/4 {1/2 cos (ω _IF t + π / 2) +1/2 cos (4ω _LO t−ω _IF t + π / 2) + cos (2ω _LO t−ω _IF t) + cos (2ω _LO t + π / 2) +1} (3-12) B23 = {cos (ω _LO t−ω _IF t) + cos (ω _LO t + ω _IF t)} × cos (ω _LO t−π / 4) + cos ² (ω _LO t−1 / 2ω _IF t) × cos ² (ω _LO t−π / 4) = 1/2 {cos (ω _IF t −π / 4) + cos (2ω _LO t−ω _IF t−π / 4) + cos (ω _IF t + π / 4) + cos (2ω _LO t + ω _IF t−π / 4)} + 1/4 {1 / 2cos (ω _IF t−π / 2) +1/2 cos (4ω _LO t−ω _IF t−π / 2) + cos (2ω _LO t−ω _IF t) + cos (2ω _LO t−π / 2) +1} (3-13) B24 = {cos (ω _LO t−ω _IF t) + cos (ω _LO t + ω _IF t)} × cos (ω _LO t + 3π / 4) + cos ² (ω _LO t−1 / 2ω _IF t) × cos ² (ω _LO t + 3π / 4) = 1/2 {cos (ω _IF t + 3π / 4) + cos (2ω _LO t−ω _IF t + 3π / 4) + cos (ω _IF t−3π / 4) + cos (2ω _LO t + ω _IF t + 3π / 4)} + 1/4 {1/2 cos (ω _IF t−π / 2) +1/2 cos (4ω _LO t−ω _IF t−π / 2) + cos (2ω _LO t−ω _IF t) + cos ( 2ω _LO t-π / 2) +1} (3-14) Then, the multiplication outputs B21, B22 and B23, B24 described above.
Is subtracted between the multiplication outputs B21 and B22 and the multiplication outputs B23 and B24 in the subtraction circuits 281 and 282, respectively. The subtracted outputs C21 and C22 are represented as follows.

C21 = cos (ω _IF t + π / 4) + cos (2ω _LO t−ω _IF t + π / 4) + cos (ω _IF t−π / 4) + cos (2ω _LO t + ω _IF t + π / 4) (3-15) ) C22 = cos (ω _IF t−π / 4) + cos (2ω _LO t−ω _IF t−π / 4) + cos (ω _IF t + π / 4) + cos (2ω _LO t + ω _IF t−π / 4) (3 -16) As is clear from the equation, the signal component generated by the multiplication of the second harmonic of the half image signal and the second harmonic of the local oscillation signal is canceled in the in-phase subtraction.

Further, the subtraction outputs C21 and C22 of the subtraction circuits 281 and 282 are respectively -π / 4 phase shift circuit 232.
And + π / 4 phase shift circuit 231 where they are respectively shifted by −π / 4 and + π / 4 to give a relative phase difference of π / 2 between the subtraction outputs C21 and C22. The phase shift signal outputs D21 and D22 are expressed as follows.

[0104] _{D21 = cos (ω IF t)} + cos (2ω LO t-ω IF t) + cos (ω IF t-π / 2) + cos (2ω LO t + ω IF t) ... (3-17) D22 = cos (ω _IF t) + cos (2ω _LO t−ω _IF t) + cos (ω _IF t + π / 2) + cos (2ω _LO t + ω _IF t) (3-18) Then, these phase shift signal outputs D21 and D22 are added to the adder circuit 2
At 91, they are added and synthesized with each other. The added synthetic signal E21 is expressed as follows. _{E21 = 2cos (ω IF t)} + 2cos (2ω LO t-ω IF t) + 2cos (2ω LO t + ω IF t) ... (3-19) i.e., in the above phase shifting circuit 231,232 + π / 4 and - [pi] / Subtracted output is D11, D
As shown in 12, the desired signal component has the same phase and the image signal component has the opposite phase. Therefore, the phase shift signal outputs D11, D
When 12 is added and synthesized by the addition circuit 291, the desired signal component cos (ω _IF t) is not canceled, and the image signal components cos (ω _IF t−π / 2) and cos (ω _IF t + π / 2) are canceled. Will be. Thus, even in the case of the local upper, both the image signal component and the half image signal component can be suppressed.

(Second Modification) FIG. 14 and FIG.
In the configuration shown in FIG. 5, the local oscillation signal generating circuit 220 shifts the phase of the local oscillation signal, so that
/ 4 different local oscillation signals are generated, and these local oscillation signals and the received signal are multiplied by the multiplication circuits 211 and 212. However, the received RF signal is phase-shifted to each other by π / It is also possible to generate four different reception RF signals and to multiply these reception RF signals and the local oscillation signal by the multiplication circuit.

FIG. 16 is a circuit block diagram showing an example of the configuration, and the same parts as those in FIG. 10 are designated by the same reference numerals. In the figure, an RF signal received by an antenna (not shown) is input to the phase shift circuit 270, and this circuit 2
After being divided into two by the distribution circuit 204 in 70, + π /
The phase is shifted by the 4 phase shift circuit 271 and the −π / 4 phase shift circuit 272, respectively. Then, a + π / 4 phase shift circuit 271
The received RF signal phase-shifted by + π / 4 is converted by the differential output circuit 273 into a signal A31 phase-shifted by + π / 4 and a signal A32 phase-shifted by −3/4, and then S
It is input to the BM 261 and mixed with the local oscillation signal. On the other hand, the received RF signal phase-shifted by -π / 4 by the -π / 4 phase shift circuit 272 is -π / by the differential output circuit 274.
After being converted into a 4-phase shifted signal A33 and its opposite phase + 3π / 4 phase shifted signal A34, it is inputted to the SBM 262 and mixed with the local oscillation signal. The circuit structure of the multiplication circuits 261 and 262 and the subsequent circuits is the same as that shown in FIG.

With such a configuration, in the reception signal generation circuit 270, the differential output circuit 271 outputs + π /
4 and -3π / 4 phase shifted received RF signals A31, A32
Is output, and the differential output circuit 272 outputs −π /
4 and + 3π / 4 phase shifted received RF signals A33, A34
Is output. Then, these received RF signals A31, A
32, A33, A34 and the local oscillation signal are multiplied by the multiplication circuit 26.
1 and 262 are respectively multiplied, whereby the multiplication outputs B31, B32 and B33, B34 down-converted to the intermediate frequency band are output.

At this time, each of the multiplication outputs B31, B32 and B33, B34 is expressed as follows. B31 = {cos (ω _LO t + ω _IF t + π / 4) + cos (ω _LO t−ω _IF t + π / 4)} × cos (ω _LO t) + cos ² (ω _LO t + 1 / 2ω _IF t + π / 4) × cos ² (Ω _LO t) = 1/2 {cos (ω _IF t + π / 4) + cos (2ω _LO t + ω _IF t + π / 4) + cos (ω _IF t−π / 4) + cos (2ω _LO t−ω _IF t + π / 4) } +1/4 {1/2 cos (ω _IF t + π / 2) +1/2 cos (4ω _LO t + ω _IF t + π / 2) + cos (2ω _LO t + ω _IF t + π / 2) + cos (2ω _LO t) +1} (3 -21) B32 = {cos (ω _LO t + ω _IF t-3π / 4) + cos (ω _LO t−ω _IF t−3π / 4)} × cos (ω _LO t) + cos ² (ω _LO t + 1 / 2ω _IF t-3π / 4) × cos ² (ω _LO t) = 1/2 {cos (ω _IF t-3π / 4) + cos (2ω _LO t + ω _IF t-3π / 4) + cos (ω _IF t + 3π / 4) + cos _{(2ω LO t-ω IF t} -3π / 4)} + 1/4 {1 / 2co s (ω IF t + π / 2) +1 _{2cos (4ω LO t + ω IF} t + π / 2) + cos (2ω LO t + ω IF t + π / 2) + cos (2ω LO t) +1} ... (3-22) B33 = {cos (ω LO t + ω IF t-π / 4) + Cos (ω _LO t−ω _IF t−π / 4)} × cos (ω _LO t) + cos ² (ω _LO t + 1 / 2ω _IF t−π / 4) × cos ² (ω _LO t) = 1/2 {Cos (ω _IF t−π / 4) + cos (2ω _LO t + ω _IF t−π / 4) + cos (ω _IF t + π / 4) + cos (2ω _LO t−ω _IF t−π / 4)} + 1/4 { 1 / 2cos (ω _IF t −π / 2) + 1 / 2cos (4ω _LO t + ω _IF t−π / 2) + cos (2ω _LO t + ω _IF t−π / 2) + cos (2ω _LO t) +1} (3- 23) B34 = {cos (ω _LO t + ω _IF t + 3π / 4) + cos (ω _LO t−ω _IF t + 3π / 4)} × cos (ω _LO t) + cos ² (ω _LO t + 1 / 2ω _IF t + 3π / 4) × cos ² (ω _LO t) = 1/2 {cos (ω _IF t + 3π / 4) + cos (2ω _LO t + ω _IF t + 3π / 4) + cos (ω _IF t + 3π / 4) + cos (2ω _LO t−ω _IF t + 3π / 4)} + 1/4 {1/2 cos (ω _IF t−π / 2) +1/2 cos (4ω _LO t + ω _IF t−π / 2) + cos (2ω _LO t + ω _IF t−π / 2) + cos (2ω _LO t) +1} (3-34) Then, the multiplication outputs B31, B32 and B33, B34 are output by the subtraction circuits 281, 282 respectively. B
Subtraction is performed between 31, B32 and the multiplication outputs B33, B34. The subtracted outputs C31 and C32 are represented as follows.

C31 = cos (ω _IF t + π / 4) + cos (2ω _LO t + ω _IF t + π / 4) + cos (ω _IF t−π / 4) + cos (2ω _LO t−ω _IF t + π / 4) (3-35) ) C32 = cos (ω _IF t−π / 4) + cos (2ω _LO t + ω _IF t−π / 4) + cos (ω _IF t + π / 4) + cos (2ω _LO t−ω _IF t−π / 4) (3 -36) As is clear from the equation, the signal component generated by the multiplication of the second harmonic of the half image signal and the second harmonic of the local oscillation signal is canceled in the in-phase subtraction.

Further, the subtraction outputs C31 and C32 of the subtraction circuits 281 and 282 are respectively -π / 4 phase shift circuit 232.
And + π / 4 phase shift circuit 231, where they are respectively shifted by −π / 4 and + π / 4 to give a relative phase difference of π / 2 between the subtracted outputs C31 and C32. The phase shift signal outputs D31 and D32 are expressed as follows.

[0111] _{D31 = cos (ω IF t)} + cos (2ω LO t + ω IF t) + cos (ω IF t-π / 2) + cos (2ω LO t-ω IF t) ... (3-27) D32 = cos (ω _IF t) + cos (2ω _LO t + ω _IF t) + cos (ω _IF t + π / 2) + cos (2ω _LO t−ω _IF t) (3-28) Then, these phase shift signal outputs D31 and D32 are added to the adder circuit 2
At 91, they are added and synthesized with each other. The added synthetic signal E31 is expressed as follows. _{E31 = cos (ω IF t)} + cos (2ω LO t + ω IF t) + cos (2ω LO t-ω IF t) ... (3-29) Then, the addition synthesis signal E31 is, IF band at IF band-pass filter 206 By removing the other signal components, the desired signal component cos (ω
_IF t) only, and is output from the IF output terminal 202. IF output signal = cos (ω _IF t) (3-30) Even with such a circuit configuration, both the image signal component and the half image signal component can be suppressed as in the case shown in FIG. Further, since the narrow band filter can be dispensed with, the whole circuit can be configured by the semiconductor element, whereby the integrated circuit can be realized.

(Third Modification) Next, FIG. 17 shows + π / 4.
By providing the phase shift circuit 231 and the −π / 4 phase shift circuit 232 in reverse, and inputting the phase shift signal outputs D41 and D42 of these phase shift circuits 231 and 232 to the subtraction circuit 292 for subtraction, The signal component is canceled.

With such a configuration, the multiplication circuit 21
From 1 and 212, the following multiplication signals B41, B42 and B43, B44 are output. B21 = 1/2 {cos (ω _IF t−π / 4) + cos (2ω _LO t + ω _IF t + π / 4) + cos (ω _IF t + π / 4) + cos (2ω _LO t−ω _IF t + π / 4)} + 1/4 {1/2 cos (ω _IF t−π / 2) +1/2 cos (4ω _LO t + ω _IF t + π / 2) + cos (2ω _LO t + ω _IF t) + cos (2ω _LO t + π / 2) +1} (3-31) B42 = 1/2 {cos (ω _IF t + 3π / 4) + cos (2ω _LO t + ω _IF t−3π / 4) + cos (ω _IF t−3π / 4) + cos (2ω _LO t−ω _IF t−3π / 4) } +1/4 {1/2 cos (ω _IF t−π / 2) +1/2 cos (4ω _LO t + ω _IF t + π / 2) + cos (2ω _LO t + ω _IF t) + cos (2ω _LO t + π / 2) +1} (3 -32) B43 = 1/2 {cos (ω _IF t + π / 4) + cos (2ω _LO t + ω _IF t−π / 4) + cos (ω _IF t−π / 4) + cos (2ω _LO t−ω _IF t−π / 4)} + 1/4 {1/2 cos (ω _IF t + π / 2) +1/2 cos (4ω _LO t + ω _IF t−π / 2) + cos (2ω _LO t + ω _IF t) + cos (2ω _LO t−π / 2) +1} (3-33) B44 = 1/2 {cos (ω _IF t−3π / 4) + cos ( 2ω _LO t + ω _IF t + 3π / 4) + cos (ω _IF t + 3π / 4) + cos (2ω _LO t−ω _IF t + 3π / 4)} + 1/4 {1/2 cos (ω _IF t + π / 2) +1/2 cos (4ω _LO t + ω _IF t−π / 2) + cos (2ω _LO t + ω _IF t) + cos (2ω _LO t−π / 2) +1} (3-34) Then, the respective multiplication outputs B41, B42 and B43, B44.
Is subtracted between the multiplication outputs B41 and B42 and between the multiplication outputs B43 and B44 in the subtraction circuits 281 and 282, respectively. The subtracted outputs C41 and C42 are represented as follows. C41 = cos (ω _IF t−π / 4) + cos (2ω _LO t + ω _IF t + π / 4) + cos (ω _IF t + π / 4) + cos (2ω _LO t−ω _IF t + π / 4) (3-35) C42 = cos (ω _IF t + π / 4) + cos (2ω _LO t + ω _IF t−π / 4) + cos (ω _IF t−π / 4) + cos (2ω _LO t−ω _IF t−π / 4) (3-36) As is clear from the equation, the signal component generated by the multiplication of the second harmonic of the half image signal and the second harmonic of the local oscillation signal is canceled because it is subtracted in phase.

Further, the subtraction outputs C41 and C42 of the subtraction circuits 281 and 282 are respectively -π / 4 phase shift circuit 232.
And + π / 4 phase shift circuit 231 where they are respectively shifted by −π / 4 and + π / 4 to give a relative phase difference of π / 2 between the subtracted outputs C41 and C42. The phase shift signal outputs D41 and D42 are expressed as follows.

[0115] _{D41 = cos (ω IF t-} π / 2) + cos (2ω LO t + ω IF t) + cos (ω IF t) + cos (2ω LO t-ω IF t) ... (3-37) D42 = cos (ω _IF t + π / 2) + cos (2ω _LO t + ω _IF t) + cos (ω _IF t) + cos (2ω _LO t−ω _IF t) (3-38) Then, these phase shift signal outputs D41 and D42 are the subtraction circuit 2
Subtracted at 92. The subtraction signal E41 is expressed as follows. _{E41 = cos (ω IF t-} π / 2) ... (3-39) thus the image signal component is subtracted signal is canceled E41 is removed IF band signals in the IF band-pass filter 206, the desired Only the signal component cos (ω _IF t−π / 2) is output from the IF output terminal 202.

(Other Modifications) In addition, the following modifications can be made to the third embodiment. That is, when the local oscillation frequency is higher than the desired frequency or when the received signal is phase-shifted and multiplied by the local oscillation signal to phase-shift and synthesize the intermediate frequency signal, the IF + π / 4 phase shift circuits 231 and −π are used.
The same effect can be obtained by reversing the / 4 phase shift circuit 232.

Further, the + π / 4 phase shift circuit is used as a 0 phase shift circuit and a −π / 2 phase shift circuit, and the −π / 4 phase shift circuit is + π /.
It is also possible to replace them with a 2-phase shift circuit and a 0-phase shift circuit.

[Fourth Embodiment] In this embodiment,
Three multiplying circuits are provided, and in each of the first, second and third multiplying circuits, the received radio frequency signal is multiplied by three local oscillation signals having a relative phase difference of π / 2,
And the multiplication outputs of the second multiplication circuit and the multiplication outputs of the second and third multiplication circuits are added, and a relative phase difference of π / 2 is given to the two addition outputs, and then these addition outputs Is added or subtracted to synthesize a desired intermediate frequency signal in which the image signal component and the half image signal component are canceled.

FIG. 18 is a circuit block diagram showing an example of the configuration of the frequency conversion circuit according to this embodiment. In the same figure, the reception RF input to the RF input terminal 301
The signals are distributed to three systems by distributors 302 and 303, and are input to three multiplication circuits 309, 310 and 311 each of which is a single balanced mixer (SBM). On the other hand, the reference local oscillation signal generated from the local oscillator 304 is distributed to three systems by the distributors 305 and 306, and then divided by the + π / 2 phase shifter 307 and the −π / 2 phase shifter 308 to π / 2. Relative phase difference is given to these local oscillation signals, and the local oscillation signals are respectively multiplied by the multiplication circuits 309, 31
0,311 is input.

Each of the multiplication circuits 309, 310 and 311 multiplies the received RF signal by the local oscillation signal having a phase difference. And the multiplier 30
The multiplication outputs of 9 and 311 are adders 313 and 314, respectively.
To the distributor 31 and the multiplication output of the multiplier 310 is input to the distributor 31.
After being divided into two systems by 2, the adders 313 and 314 are added.
Is input to In the adders 313 and 314, the multiplication outputs of the multipliers 309 and 311 and the multiplication output of the multiplier 310 are added and combined, respectively.

The addition outputs of the adders 313 and 314 are given a relative phase difference of π / 2 by the + π / 4 phase shifter 315 and the −π / 4 phase shifter 316, and
The adder 317 performs addition synthesis. And this adder 3
The addition output of 17 is passed through the IF band pass filter 318 and then output from the IF output terminal 319 as a reception intermediate frequency signal.

Next, the cancel operation of the image signal component and the half image signal component by the circuit configured as described above will be described. Here, when the local oscillation signal frequency ω _LO is lower than the RF signal frequency ω _LO + ω _IF ,
That is, the case where the frequency spectrum has the relationship shown in FIG.

First, the cancellation of the half image signal will be described. The half image signal input to the RF input terminal 301 is expressed as cos (ω _LO + ω _IF / 2) t (4-1), and the local oscillation signal input to the first multiplication circuit 309 is cos (ω _LO t + π / 2) (4-2) The local oscillation signal input to the second multiplication circuit 310 is cosω _LO t (4-3) The local oscillation signal input to the third multiplication circuit 311 is cos (ω _LO t-π / 2) (4-4).

Here, since the interference due to the half image signal falls into the intermediate frequency band due to the mixing of the double wave of the input signal and the double wave of the local oscillation signal as described above, The multiplication output of the multiplication circuit 309 of 1 is (cos (ω _LO + ω _IF / 2) t) ² × (cos (ω _LO t + π / 2)) ² = − cos ω _IF t (4-5) Second multiplication circuit The output of 310 is (cos (ω _LO + ω _IF / 2) t) ² × (cosω _LO t) ² = cosω _IF t (4-6) The output of the third multiplication circuit 311 is (cos (ω _LO + ω _IF / 2) t) ² × (cos (ω _LO t−π / 2) ² = − cos ω _IF t (4-7).

Then, these multiplication outputs are added to the adder 31.
When added at 3,314, respectively and the addition output _{(- cosω IF t) + (} cosω IF t) = 0 (cosω IF t) + (- cosω IF t) = 0 , and the half-image signal is canceled.

Next, cancellation of image signals will be described. If the received RF signal and the image signal input to the RF input terminal 301 are cos (ω _LO + ω _IF ) t (4-8) cos (ω _LO −ω _IF ) t (4-9), respectively. The multiplication output of each multiplication circuit 309, 310, 311 is expressed as follows.

[0127] multiplication output of the first multiplier circuit 309 RF signals; sinω _IF t ... (4-10) Image _{signals; - sinω IF t ... (4-11} ) multiplied by the output of the second multiplier circuit 310 RF signals ; cos .omega _IF t image signal; cosω _IF t ... (4-12) multiplied by the output of the third multiplier circuit 311 RF _{signals; - sinω IF t ... (4-13} ) the image signal; sinω _IF t ... (4-14 ) Then, when the addition output of the first multiplication circuit 309 and the multiplication output of the second multiplication circuit 310 are added and synthesized by the adder 313, the addition and synthesis output is

(Equation 4)

In addition, the multiplication output of the second multiplication circuit 310 and the multiplication output of the third multiplication circuit 311 are added to the adder 31.
When the addition and synthesis is performed in 4, the addition and synthesis output is

(Equation 5)

It becomes:

Then, the addition output of the adder 313 is +
When the π / 4 phase shifter 315 shifts + π / 4 phase and the addition output of the adder 314 is shifted by −π / 4 phase shifter 316 by −π / 4, the adder 317 performs addition synthesis. , Its addition and synthesis output is

(Equation 6)

RF signal: 2√2 cos ω _IF t Image signal: 0, and the image signals are canceled.

When the local oscillation signal frequency ω _LO is higher than the RF signal frequency ω _LO + ω _IF , that is, when the frequency spectrum has the relationship shown in FIG. B (b),
By replacing + π / 4 phase shifter 315 with −π / 4 phase shifter 316 and replacing −π / 4 phase shifter 316 with + π / 4 phase shifter 315, image signal interference and half image interference Can be offset at the same time.

As described above, according to the frequency conversion circuit shown in FIG. 18, the interference of the image signal and the interference of the half image can be canceled at the same time. Moreover, since the number of multiplication circuits 309, 310, 311 can be three, the circuit configuration can be simplified and downsized as compared with the circuit shown in FIG. 1 of the first embodiment.

In the frequency conversion circuit of the fourth embodiment, it is premised that the levels of the two signals input to the IF adders 313, 314 and 317 and the IF subtractor 321 are equal. Has become. Therefore, in the above configuration, all the multiplication circuits 309, 310 and 311, the RF distributors 302 and 303, the local oscillator signal distributor 305,
The levels are adjusted by the 306 and the IF distributor 312, and signals having the same level are input to the IF adders 313, 314, 317 and the IF subtractor 321.

Next, various modified examples according to the fourth embodiment will be described. (First Modification) In the circuit shown in FIG. 19, the + π / 4 phase shifter 315 and −π / 4 phase shifter 316 shown in FIG. 18 are replaced by −π / 4 phase shifter 316 and + π / 4 shifter, respectively. Phaser 31
5, and subtractor 321 instead of adder 317
Is used. Even in such a configuration, the image signal component can be canceled. In addition,
For the half image signal component, adders 313, 3
It is canceled by the addition synthesis of the multiplication output in 14.

(Second Modification) In the circuit shown in FIG. 20, when a local oscillation signal is supplied to each of the multipliers 309, 310, 311, a reference generated by the local oscillator 304 is applied to the multiplier 309. Of the local oscillator signal is supplied to the multiplier 310 as it is, and the reference local oscillator signal generated from the local oscillator 304 is supplied to the multiplier 311 by the phase shift of + π / 2 by the + π / 2 phase shifter 330. , The reference local oscillation signal generated from the local oscillator 304 is applied to the π phase shifter 33.
In the case of 1, the phase is shifted by π and supplied.

According to such a configuration, each multiplier 30
As in the circuit shown in FIG.
A local oscillation signal having a relative phase difference of / 2 can be supplied, whereby a multiplication output having a relative phase difference of π / 2 can be output from each multiplier 309, 310, 311. Therefore, this circuit can cancel both the half image signal component and the image signal component as in the circuit shown in FIG.

(Third Modification) In the circuit shown in FIG. 21, the −π / 4 phase shifter 316 and the + π / 4 phase shifter 315 shown in FIG. 20 are replaced by + π / 4 phase shifters 315 and −π, respectively. /
A four-phase shifter 316 is used, and a subtractor 321 is used instead of the adder 317. Even with such a configuration, the image signal component can be reliably canceled by adding the signals output from the + π / 4 phase shifter 315 and the −π / 4 phase shifter 316 by the adder 317.

(Fourth Modification) In the circuit shown in FIG. 22, when a local oscillation signal is supplied to each of the multipliers 309, 310 and 311, a signal generated from the local oscillator 304 is supplied to the multiplier 309. Is phase-shifted by the π-phase shifter 331 and supplied,
The signal generated from the local oscillator 304 is supplied to the multiplier 310 by -π / 2 phase shift by the -π / 2 phase shifter 308, and further supplied to the multiplier 311. The signals are supplied in the same phase.

Even with this configuration, each multiplier 30
A local oscillation signal having a relative phase difference of π / 2 can be supplied to each of 9, 310 and 311.
The multiplication outputs having the relative phase difference of 2 are provided to the multipliers 309 and 3 respectively.
It can be output from 10, 311. Therefore,
This circuit can also cancel the same half image signal component and image signal component as in the circuit shown in FIG.

In the circuit shown in FIG. 22,
The −π / 2 phase shifter 308 is replaced with a + π / 2 phase shifter, and the −π / 4 phase shifter 316 and the + π / 4 phase shifter 315 are + π / 4 phase shifter 315 and −π / 4 shifter, respectively. Phaser 3
It may be replaced with 16. Even with this configuration, both the image signal component and the half image signal component can be canceled in the same manner as the above configurations.

(Other Modifications) Further, the circuits of FIGS. 19 to 22 have a frequency spectrum relationship shown in FIG. B (a).
In the case where the frequency spectrum relationship is as shown in FIG. B (b), it is handled by inverting the + π / 4 phase shifter 315 and the −π / 4 phase shifter 316. it can.

[Fifth Embodiment] The fifth embodiment is a further improvement of the fourth embodiment.
The three phase shifters are used when generating three local oscillation signals each having a relative phase difference of π / 2.

FIG. 23 shows an example of the configuration of the frequency conversion circuit according to this embodiment. In the figure, the same parts as those in FIG.

The circuit for supplying the local oscillation signal to each of the multipliers 309, 310 and 311 supplies the reference local oscillation signal generated from the local oscillator 304 to the multiplier 309 by + π.
The + / 2 phase shifter 307 supplies + π / 2 phase shift, and the multiplier 310 supplies the reference local oscillation signal generated from the local oscillator 304 by + π phase shifter 331 + π phase shift. In addition, the local oscillator 304 is added to the multiplier 311.
The reference local oscillation signal generated from the -π / 2 phase shifter 3
In 08, the phase is shifted by −π / 2 and supplied.

With such a configuration, each multiplier 30
The following local oscillation signals are supplied to 9, 310 and 311 respectively. Here, the local oscillation signal frequency ω
_{The case where LO} is lower than the RF signal frequency ω _LO + ω _IF , that is, the case where the frequency spectrum has the relationship shown in FIG.

[0147] The first multiplier circuit 309 - the sinω _LO t ... (5-1) second multiplying circuit _{310 - cosω LO t ... (5-2} ) in the third multiplying circuit 311 sin .omega _LO t … (5-3) are supplied respectively.

Here, assuming that the half image signal input to the RF input terminal 301 is cos (ω _LO + ω _IF / 2) t (5-4), the interference due to this half image signal is as described above. Since the second harmonic of the input signal and the second harmonic of the local oscillation output are mixed and fall into the IF band, the multiplication output of the first multiplication circuit 309 is (cos (ω _LO + ω _IF / 2) t) ² × (−sin ω _LO t) ² = − cos ω _IF t (5-5) The multiplication output of the second multiplication circuit 310 is (cos (ω _LO + ω _IF / 2) t) ² × (− cos ω _LO t) ² = cos ω _IF t (5-6) The output of the third multiplication circuit 311 is (cos (ω _LO + ω _IF / 2) t) ² × (sin ω _IF t) ² = − cos ω _IF t (5-7 ).

Then, these multiplication outputs are added to the adder 31.
When added at 3,314, respectively and the addition output _{(- cosω IF t) + (} cosω IF t) = 0 (cosω IF t) + (- cosω IF t) = 0 , and the half-image signal is canceled.

On the other hand, the received RF signal and the image signal input to the RF input terminal 301 are cos (ω _LO + ω _IF ) t (5-8) cos (ω _LO −ω _IF ) t (5-9), respectively. Then, the multiplication output of each multiplication circuit 309, 310, 311 is expressed as follows.

[0151] multiplication output of the first multiplier circuit 309 RF signals; sinω _IF t ... (5-10) Image _{signals; - sinω IF t ... (5-11} ) multiplied by the output of the second multiplier circuit 310 RF signals -Cos ω _IF t image signal; -cos ω _IF t (5-12) The multiplication output of the third multiplication circuit 311 is an RF signal; -sin ω _IF t ... (5-13) image signal; sin ω _IF t ... (5 -14) Then, when the addition output of the first multiplication circuit 309 and the multiplication output of the second multiplication circuit 310 are added and synthesized by the adder 313, the addition and synthesis output is

(Equation 7)

In addition, the multiplication output of the second multiplication circuit 310 and the multiplication output of the third multiplication circuit 311 are added to the adder 31.
When the addition and synthesis is performed in 4, the addition and synthesis output is

(Equation 8)

It becomes:

Then, the addition output of the adder 313 is-
When the adder 317 adds and combines the phase-shifted by the phase-shifter 316 of -π / 4 and the phase-shifted output of the adder 314 by the phase-shifter +315 by + π / 4, The addition and synthesis output is

(Equation 9)

Therefore, the image signals are canceled.

When the local oscillation signal frequency ω _LO is higher than the RF signal frequency ω _LO + ω _IF , that is, when the frequency spectrum has the relationship shown in FIG. B (b),
By replacing + π / 4 phase shifter 315 with −π / 4 phase shifter 316 and replacing −π / 4 phase shifter 316 with + π / 4 phase shifter 315, image signal interference and half image interference Can be offset at the same time.

As described above, according to the frequency conversion circuit shown in FIG. 23, the interference of the image signal and the interference of the half image can be canceled at the same time. Moreover, since the number of multiplication circuits 309, 310, 311 can be three, the circuit configuration can be simplified and downsized as compared with the circuit shown in FIG. 1 of the first embodiment.

In the frequency conversion circuit of the fifth embodiment, it is assumed that the levels of the two signals input to the IF adders 313, 314 and 317 and the IF subtractor 321 are equal. Has become. Therefore, in the above configuration, all the multiplication circuits 309, 310 and 311, the RF distributors 302 and 303, the local oscillator signal distributor 305,
The levels are adjusted by the 306 and the IF distributor 312, and signals having the same level are input to the IF adders 313, 314, 317 and the IF subtractor 321.

Next, various modifications of the fifth embodiment will be described. (First Modification) The circuit shown in FIG. 24 is a modification of the circuit shown in FIG. 23, and includes −π / 4 phase shifter 316 and + π.
The / 4 phase shifter 315 is replaced with a + π / 4 phase shifter 315 and a −π / 4 phase shifter 316, respectively, and an adder 317 is used.
Instead of this, a subtractor 321 is used.

Even in such a structure, the image signal component can be canceled. The half image signal component is canceled by the addition and synthesis of the multiplication outputs in the adders 313 and 314.

(Second Modification) In the circuit shown in FIG. 25, when a local oscillation signal is supplied to each of the multipliers 309, 310 and 311, a reference generated by the local oscillator 304 is applied to the multiplier 309. Local oscillation signal of + 3π / 4 phase shifter 33
2 supplies + 3π / 4 phase shift, and the multiplier 310 supplies the reference local oscillation signal generated from the local oscillator 304 by + π / 4 phase shifter 333 + π / 4 phase shift and supplies it.
Further, the reference local oscillation signal generated from the local oscillator 304 is fed to the multiplier 311 by the −π / 4 phase shifter 334.
The phase is shifted by π / 4 and supplied. FIG.
-Π / 4 phase shifter 316 and + π / 4 phase shifter 3 shown in FIG.
15 are replaced with a + π / 4 phase shifter 315 and a −π / 4 phase shifter 316, respectively.

With such a configuration, each multiplier 30
As in the circuit of FIG. 23, each of 9, 310, 311 has a π
A local oscillation signal having a relative phase difference of / 2 can be supplied, whereby a multiplication output having a relative phase difference of π / 2 can be output from each multiplier 309, 310, 311. Therefore, this circuit can cancel both the half image signal component and the image signal component as in the circuit shown in FIG.

(Third Modification) In the circuit shown in FIG. 26, the + π / 4 phase shifter 315 and the −π / 4 phase shifter 316 shown in FIG. 25 are replaced by −π / 4 phase shifter 316 and + π, respectively. /
A four-phase shifter 315 is used, and a subtractor 321 is used instead of the adder 317. With such a configuration, as a result, the image signal component is canceled similarly to the circuit of FIG.

(Fourth Modification) The circuit shown in FIG. 27 is a modification of the circuit shown in FIG.
When the local oscillation signal is supplied to 10, 311, the multiplier 3
For 09, the reference local oscillation signal generated from the local oscillator 304 is converted into −3π / 4 by the −3π / 4 phase shifter 335.
The phase-shifted signal is supplied, and the reference local oscillation signal generated from the local oscillator 304 is supplied to the multiplier 310 by + 3π / 4.
The phase shifter 332 supplies + 3π / 4 phase shift, and the multiplier 311 further shifts the reference local oscillation signal generated from the local oscillator 304 by + π / 4 phase shifter 334 to + π / 4 phase shift. It is something that is supplied.

Even with this configuration, each multiplier 30
A local oscillation signal having a relative phase difference of π / 2 can be supplied to each of 9, 310 and 311.
The multiplication outputs having the relative phase difference of 2 are provided to the multipliers 309 and 3 respectively.
It can be output from 10, 311. Therefore,
With this circuit as well, the same half image signal component and image signal component as in the case of the circuit shown in FIG. 25 can be canceled.

(Fifth Modification) The circuit shown in FIG. 28 is a modification of the circuit shown in FIG.
The 4-phase shifter 315 and the -π / 4 phase shifter 316 are replaced with a -π / 4 phase shifter 316 and the + π / 4 phase shifter 315, respectively, and the adder 317 is replaced with a subtractor 321.

With this structure, the image signal component can be canceled similarly to the circuit shown in FIG. Regarding the half image signal component,
It is canceled by the addition synthesis of the multiplication outputs in the adders 313 and 314.

(Sixth Modification) The circuit shown in FIG. 29 is a modification of the circuit shown in FIG.
When the local oscillation signal is supplied to 9, 310, 311, the reference local oscillation signal generated from the local oscillator 304 is supplied to the multiplier 309 by -π / 4 by the phase shifter 334.
4 phase-shifted and supplied, and to the multiplier 310, the reference local oscillation signal generated from the local oscillator 304 is -3π /
The 4 phase shifter 335 supplies the phase shifted by -3π / 4, and further supplies the multiplier 311 with the reference local oscillation signal generated from the local oscillator 304 by + 3π / 4 phase shifter 334.
It is designed to be supplied with four phase shifts.

Even with such a configuration, each multiplier 30
A local oscillation signal having a relative phase difference of π / 2 can be supplied to each of 9, 310 and 311.
The multiplication outputs having the relative phase difference of 2 are provided to the multipliers 309 and 3 respectively.
It can be output from 10, 311. Therefore,
With this circuit as well, the same half image signal component and image signal component as in the case of the circuit shown in FIG. 25 can be canceled.

(Seventh Modification) The circuit shown in FIG. 30 has the IF + π / 4 phase shifter 315 and −π shown in FIG.
The / 4 phase shifter 316 is replaced with a -π / 4 phase shifter 316 and a + π / 4 phase shifter 315, respectively, and an adder 317 is used.
Instead of this, a subtractor 321 is used. Even with such a configuration, as a result, the image signal component is canceled similarly to the circuit of FIG.

(Eighth Modification) The circuit shown in FIG. 31 is a modification of the circuit shown in FIG. 29, and each multiplier 309, 3 is provided.
When the local oscillation signal is supplied to 10, 311, the multiplier 3
09, the reference local oscillation signal generated from the local oscillator 304 is + π / 4 phase-shifted by the + π / 4 phase shifter 333 and supplied, and the multiplier 310 receives the local oscillator 3 signal.
The reference local oscillation signal generated from 04 is supplied by -π / 4 phase shift by the −π / 4 phase shifter 334, and further supplied to the multiplier 311.
In contrast, the reference local oscillation signal generated from the local oscillator 304 is -3π / 4 phase-shifted by the -3π / 4 phase shifter 335 and supplied.

Even with such a configuration, each multiplier 30
A local oscillation signal having a relative phase difference of π / 2 can be supplied to each of 9, 310 and 311.
The multiplication outputs having the relative phase difference of 2 are provided to the multipliers 309 and 3 respectively.
It can be output from 10, 311. Therefore,
With this circuit as well, the same half image signal component and image signal component as in the case of the circuit shown in FIG. 25 can be canceled.

(Ninth Modification) The circuit shown in FIG. 32 is a modification of the circuit shown in FIG. 31 and has an IF of + π /.
The 4-phase shifter 315 and the -π / 4 phase shifter 316 are replaced with a -π / 4 phase shifter 316 and the + π / 4 phase shifter 315, respectively, and the adder 317 is replaced with a subtractor 321.

Even with this structure, the image signal component can be canceled similarly to the circuit shown in FIG. Regarding the half image signal component,
It is canceled by the addition synthesis of the multiplication outputs in the adders 313 and 314.

(Other Modifications) Further, the frequency conversion circuits shown in FIGS. 19 to 32 are configured so as to correspond to the case where the frequency spectrum relationship is as shown in FIG. B (a). In the case of the relationship B of FIG. 7B, it can be dealt with by inverting the + π / 4 phase shifter 315 and the −π / 4 phase shifter 316 for IF.

[Sixth Embodiment] This embodiment is
The differential conversion means is used to generate a pair of differential local oscillation signals having a relative phase difference of π or a pair of differential reception high-frequency signals having a relative phase difference of π, and generate these differential signal pairs. π
And a two-system differential signal pair having a relative phase difference of π / 2, which is generated based on the above-mentioned differential signal pair, by multiplication with a two-system received high-frequency signal having a relative phase difference of / 2 or a local oscillation signal. Multiplication with the received high frequency signal or the local oscillation signal is performed, respectively. Then, subtraction synthesis is performed for each of the two pairs of multiplication signals obtained by this multiplication to cancel the interference component of the f _I / 2 image signal, that is, the half image signal, and further, each of the subtraction synthesis signals is π / 2. The interfering components of the image signal are canceled by adding the relative phase difference of and then combining.

FIG. 33 is a circuit block diagram showing an example of the configuration of the frequency conversion circuit according to this embodiment. In the figure, reference numeral 410 is an RF signal input terminal for inputting a received signal. The received RF signal input to the RF signal input terminal 410 is distributed to two systems by a distributor 411, and then multipliers 414 and 415 are respectively provided. Entered in. on the other hand,
Reference numeral 420 denotes a local oscillation signal input terminal (Lo signal input terminal) for inputting a local oscillation signal (local signal). The local oscillation signal input to this input terminal 420 is input to the differential converter 4
22.

The differential converter 422 is a differential converter that converts the above local signal into a pair of differential local oscillation signals having a relative phase difference of π, and this differential local oscillation signal pair is π / 2.
After being converted into a pair of differential local oscillation signals of two systems having a relative phase difference of π / 2 by the phase shift distributor 423, they are respectively input to the multipliers 414 and 415 for each system.

In the multipliers 414 and 415, the received RF signal output from the distributor 411 and the π /
The two-system differential local oscillation signal pairs output from the two-phase shift distributor 423 are multiplied, and the two-system multiplication signal pairs thus obtained are input to the subtracters 436 and 437, respectively.

In these subtractors 436 and 437, subtraction is performed for each of the above-mentioned multiplication signal pairs, and the subtraction signal is π /
It is input to the two-phase shift combiner 439. In the π / 2 phase shift combiner 439, the subtracted signals are given a relative phase difference of π / 2, and then the subtracted signals after the phase shift are added and combined with each other. Then, the added and synthesized signal is output as an intermediate frequency signal from the IF signal output terminal 440 to, for example, a demodulation circuit in the subsequent stage.

The operation of canceling the half image signal component and the image signal component by the circuit configured as described above will be described. The case where the local frequency is lower than the desired frequency will be described.

The received RF signal (desired signal), the image signal and the half image signal input to the RF signal input terminal 410 are cos (ω _L t + ω _I t) cos (ω _L t-ω _I t) cos ( When _{ω L t + 1/2 ω} I t)) and, these reception input signal is input to the multiplier 414 and 415 after being distributed to the received distribution signals rd1, rd2 two systems in distributor 411. The received distribution signals rd1 and rd2 at this time are shown in the following equations. Where cos ² (ω _L
t + 1/2 ω _I t) is the half image signal cos (ω _L t + 1/2 ω _I
It is the second harmonic of t).

Received distribution signal rd1 = cos (ω _L t + ω _I t) + cos (ω _L t-ω _I t) + cos ² (ω _L t + 1/2 ω _I t) = cos (ω _L t + ω _I t) + cos (ω _L t-ω _I t) +1/2 {cos (2ω _L t + ω _I t) +1} (6-1) Received distribution signal rd2 = cos (ω _L t + ω _I t) + cos (ω _L t-ω _I t) + cos ² (ω _L t + 1/2 ω _I t) = cos (ω _L t + ω _I t) + cos (ω _L t-ω _I t) +1/2 {cos (2ω _L t + ω _I t) +1} (6-2) FIG. 34 shows the vectors of these reception distribution signals rd1 and rd2.

On the other hand, the local signal input to the Lo signal input terminal 420 is converted into a pair of local differential signals lb1 and lb1 'by the differential converter 422 and input to the π / 2 phase shift distributor 423. It The local differential signals lb1 and lb1 'at this time are shown in the following equations. Where cos ² (ω _L
t) and cos ² (ω _L t + π) are the second harmonics of the differential signals cos (ω _L t) and cos (ω _L t + π) obtained by differentially converting the local signal.

Local differential signal lb1 = cos (ω _L t) + cos ² (ω _L t) = cos (ω _L t) +1/2 {cos (2ω _L t) +1} (6-3) Local differential signal lb1 '= cos (ω _L t + π) + cos ² (ω _L t + π) = cos (ω _L t + π) +1/2 {cos (2ω _L t) +1}… ( 6-4) FIG. 35 shows the vectors of these local differential signals lb1 and lb1 '.

The local differential signals lb1 and lb1 'are π
A 1/2 phase shift distributor 423 converts the signals into first local phase shift signals lp1 and lp1 ′ having a relative phase difference of π / 2 and second local phase shift signals lp2 and lp2 ′, and multipliers 414 and 414, respectively. 415 is input. However, here, the case where lp1 and lp1 'are advanced by π / 2 will be described. The local phase shift signals lp1, lp1 'and lp2, lp2' at this time are shown in the following equations.

Here, cos ² (ω _L t + π / 2) and cos
² (ω _L t-π / 2) and cos ² (ω _L t) and cos ² (ω _L t +
π) is the phase shift signal cos (ω _L t + π / 2)
And cos (ω _L t-π / 2) and cos (ω _L t) and cos (ω _L t + π) are the second harmonics.

Local phase shift signal lp1 = cos (ω _L t + π / 2) + cos ² (ω _L t + π / 2) +1/2 {cos (2ω _L t + π / 2) +1} = cos (ω _L t + π / 2) +1/2 {cos (2ω _L t + π) +1} +1/2 {cos (2ω _L t + π / 2) +1}… (6-5) Local phase shift signal lp1 '= cos (ω _L t-π / 2) + cos ² (ω _L t-π / 2) +1/2 {cos (2ω _L t + π / 2) +1} = cos ( ω _L t-π / 2) +1/2 {cos (2ω _L t-π) +1} +1/2 {cos (2ω _L t + π / 2) +1}… (6-6) Local transfer Phase signal lp2 = cos (ω _L t) + cos ² (ω _L t) +1/2 {cos (2ω _L t) +1} = cos (ω _L t) +1/2 {cos (2ω _L t) +1} +1/2 {cos (2ω _L t) +1} (6-7) Local phase shift signal lp2 ′ = cos (ω _L t + π) + cos ² (ω _L t + π) +1 / 2 {cos (2ω _L t) +1} = cos (ω _L t + π) +1/2 {cos (2ω _L t) +1} +1/2 {cos (2ω _L t) +1}… (6-8) FIG. 36 shows the vectors of these local phase shift signals lp1, lp1 'and lp2, lp2'.

Reception distribution signal rd1 and local phase shift signal l
p1, lp1 'are multiplied by the multiplier 414 to obtain the multiplication signal m
The received distribution signal rd2 and the local phase shift signals lp2 and lp2 'are multiplied by the multiplier 415 to obtain multiplication signals mo2 and mo2'. Multiplication signal m at this time
o1, mo1 'and mo2, mo2' are shown in the following equations.

Multiplication signal mo1 = {cos (ω _L t + ω _I t) + cos (ω _L t-ω _I t)} * cos (ω _L t + π / 2) +1/2 {cos (2ω _L t + ω _I t) +1} * 1/2 {cos (2ω _L t + π) +1} +1/2 {cos (2ω _L t + ω _I t) +1} * 1/2 {cos ( 2ω _L t + π / 2) +1} = 1/2 {cos (ω _I t-π / 2) + cos (2ω _L t + ω _I t + π / 2) + cos (ω _I t + π / 2) + cos (2ω _L t-ω _I t + π / 2)} + 1/4 {1/2 [cos (ω _I t-π) + cos (4ω _L t + ω _I t + π)] + cos (2ω _L t + ω _I t) + cos (2ω _L t + π) +1} +1/4 {1/2 [cos (ω _I t-π / 2) + cos (4ω _L t + ω _I t + π / 2)] + cos (2ω _L t + ω _I t) + cos (2ω _L t + π / 2) +1}… (6-9) Multiplication signal mo1 ′ = {cos (ω _L t + ω _I t) + cos (ω _L t-ω _I t)} * cos (ω _L t-π / 2) +1/2 {cos (2ω _L t + ω _I t) +1} * 1/2 { cos (2ω _L t-π) +1} +1/2 {cos (2ω _L t + ω _I t) +1} * 1/2 {cos (2ω _L t + π / 2) +1} = 1 / 2 (cos (ω _I t + π / 2) + cos (2ω _L t + ω _I t-π / 2) + cos (ω _I t-π / 2) + cos (2ω _L t-ω _I t-π / 2)} + 1/4 {1/2 [cos (ω _I t + π) + cos (4ω _L t + ω _I t-π)] + cos (2ω _L t + ω _I t) + cos (2ω _L t-π) +1} +1/4 {1/2 [cos (ω _I t-π / 2) + cos (4ω _L t + ω _I t + π / 2)] + cos (2ω _L t + _{ω I t) + cos (2ω} L t + π / 2) +1} ... (6-10) multiplication signal _{o2 = {cos (ω L t} + ω I t) + cos (ω L t-ω I t)} * cos (ω L t) +1/2 {cos (2ω L t + ω I t) +1} * 1/2 {cos (2ω _L t) +1} +1/2 {cos (2ω _L t + ω _I t) +1} * 1/2 {cos (2ω _L t) +1} = 1/2 {cos (ω _I t) + cos (2ω _L t + ω _I t) + cos (ω _I t) + cos (2ω _L t-ω _I t)} +1/4 {1/2 [cos (ω _I t) + cos (4ω _L t + ω _I t)] + cos (2ω _L t + ω _I t) + cos (2ω _L t) +1} +1/4 {1/2 [cos (ω _I t) + cos (4ω _L t + ω _I t)] + cos (2ω _L t + ω _I t) + cos (2ω _L t) +1} (6-11) Multiplication signal mo2 ′ = {cos (ω _L t + ω _I t) + cos (ω _L t-ω _I t)} * cos (ω _L t + π) +1/2 {cos (2ω _L t + ω _I t) +1} * 1/2 {cos (2ω _L t) +1} +1/2 {cos (2ω _L t + ω _I t) +1} * 1/2 {cos (2ω _L t) +1} = 1/2 {cos (ω _I t -π) + cos (2ω _L t + ω _I t + π) + cos (ω _I t + π) + cos (2ω _L t-ω _I t + π)} + 1/4 {1/2 [cos ( ω _I t) + cos (4ω _L t + ω _I t)] + cos (2ω _L t + ω _I t) + cos (2ω _L t) +1} +1/4 {1/2 [cos (ω _I t) + cos (4ω _L t + ω _I t)] + cos (2ω _L t + ω _I t) + cos (2ω _L t) +1} (6-12) FIG. 37 shows these multiplication signals mo1, mo1 'and mo2
The vector of mo2 'is shown.

The multiplication signals mol and mol 'are subtracted from the subtractor 436.
Is subtracted and combined by the subtractor 437, and the multiplication signals mo2 and mo2 ′ are subtracted and combined by the subtractor 437 to obtain subtracted signals so1 and so2, respectively.
It becomes so2. These subtracted signals so1 and so2 are shown in the following equations.

Subtraction signal so1 = cos (ω _I t-π / 2) + cos (2ω _L t + ω _I t + π / 2) + cos (ω _I t + π / 2) + cos (2ω _L t- ω _I t + π / 2) (6-13) Subtraction signal so2 = cos (ω _I t) + cos (2ω _L t + ω _I t) + cos (ω _L t) + cos (2ω _L t-ω _It ) (6-14) FIG. 38 shows a vector diagram of these subtraction signals so1 and so2.

As is clear from these equations (6-13) and (6-14), the signal component generated by the multiplication of the second harmonic of the half image signal and the second harmonic of the local differential signal, and All the signal components generated by the multiplication of the second harmonic of the half image signal and the second harmonic of the local phase shift signal are canceled.

Next, the subtracted signals so1 and so2 are π / 2.
The phase shift combiner 439 gives a relative phase difference of π / 2, and then the signals are added and combined with each other. However, here, it is assumed that the subtraction signal so1 is delayed by π / 2 for subtraction synthesis. The synthetic signal obtained by this addition synthesis is shown in the following equation.

[0195] Synthesis signal _{= {cos (ω I t-} π) + cos (2ω L t + ω I t) + cos (ω I t) + cos (2ω L t-ω I t)} - {cos (ω _I t) + cos (2ω _L t + ω _I t) + cos (ω _I t) + cos (2ω _L t-ω _I t)} = 2cos (ω _I t-π)… (6-15) This ( As is clear from the expression (6-15), the image signal component is canceled by the addition synthesis of the addition signals given the relative phase difference of π / 2.

As described above, according to the above circuit, the desired signal component is not canceled and both the image signal component and the half image signal component can be canceled.

In the above description, the subtraction signal so1 is delayed by π / 2 in the π / 2 phase shift combiner 439 to perform addition synthesis, but the same result is obtained even when the subtraction signal so1 is advanced by π / 2. Is obtained.

In the above description, the case where the local frequency is lower than the desired frequency has been described, but when the local frequency is higher than the desired frequency, the π / 2 phase shift combiner 439 is used when the local frequency is lower than the desired frequency. If the configuration is such that the phase shift is opposite to that at the time, or if addition or subtraction synthesis is performed at the time opposite to the synthesis when the local frequency is lower than the desired frequency, the image signal similar to the above configuration is obtained. Both the component and the half image signal component can be canceled.

The frequency conversion circuit described with reference to FIG. 33 can be modified as follows. (First Modification) In the circuit shown in FIG. 39, the received RF signal is phase-shifted / distributed by the π / 2 phase shift distributor 513 into two systems of received distribution signals rp1, rp2 having a relative phase difference of π / 2. Input to the multipliers 514 and 515, and the local signal is converted into a differential local signal pair having a phase difference of π in the differential conversion distributor 422, and then the differential local signal pair is converted into two differential systems. Local signal pair lb1, l
It is distributed to b1 'and lb2, lb2' and input to the multipliers 514 and 515, respectively. And the above 2
The reception distribution signals rp1, rp2 of the system and the differential local signal pairs lb1, lb1 'and lb2, lb2' of the two systems are multiplied by the multipliers 514, 515.

With such a configuration, when the local frequency is lower than the desired frequency, the cancel operation of the half image signal component and the image signal component is performed as follows.

The received RF signal (desired signal), the image signal and the half image signal input from the RF signal input terminal 410 are cos (ω _L t + ω _I t) cos (ω _L t-ω _I t) cos ( ω _L t + 1/2 ω _I t), these received input signals are π / 2 phase shift divider 5
After being distributed to the two systems of reception distribution signals rp1 and rp2 having a relative phase difference of π / 2 at 13, multipliers 514 and 515 are used.
Is input to Reception phase shift signals rp1 and rp2 at this time
Is shown in the following equation. However, here, a case where rp1 is advanced by π / 2 will be described. Where cos ² (ω _L t + 1/2 ω _I t + π
/ 2) and cos ² (ω _L t + 1/2 ω _I t) are the phase shift signals cos (ω _L t + 1/2 ω _I t + π / 2) and cos
a second harmonic _{(ω L t + 1/2} ω I T).

Received phase shift signal rp1 = cos (ω _L t + ω _I t + π / 2) + cos (ω _L t-ω _I t + π / 2) + cos ² (ω _L t + 1/2 ω _I t + π / 2) = cos (ω _L t + ω _I t + π / 2) + cos (ω _L t-ω _I t + π / 2) +1/2 {cos (2ω _L t + ω _I t + π) +1} (6-16) Received phase shift signal rp2 = cos (ω _L t + ω _I t) + cos (ω _L t-ω _I t) + cos ² (ω _L t + 1 / 2 ω _I t) = cos (ω _L t + ω _I t) + cos (ω _L t-ω _I t) +1/2 {cos (2ω _L t + ω _I t) +1}… (6-17 On the other hand, the local signal input to the Lo signal input terminal 420 is converted by the differential conversion distributor 422 into two pairs of local differential signals lb1, lb1 'and lb2, lb2'.
It is distributed and input to the multipliers 514 and 515, respectively. The local differential signals lb1, lb1 'and lb2, lb2' at this time are shown in the following equations. Where cos ² (ω _L
t) and cos ² (ω _L t + π) are the second harmonics of the differential signals cos (ω _L t) and cos (ω _L t + π) obtained by differentially converting the local signal.

Local differential signal lb1 = cos (ω _L t) + cos ² (ω _L t) = cos (ω _L t) +1/2 {cos (2ω _L t) +1} (6-18) Local differential signal lb1 '= cos (ω _L t + π) + cos ² (ω _L t + π) = cos (ω _L t + π) +1/2 {cos (2ω _L t) +1}… ( 6-19) Local differential signal lb2 = cos (ω _L t) + cos ² (ω _L t) = cos (ω _L t) +1/2 {cos (2ω _L t) +1}… (6-20 ) Local differential signal lb2 ′ = cos (ω _L t + π) + cos ² (ω _L t + π) = cos (ω _L t + π) +1/2 {cos (2ω _L t) +1}… (6-21) Received phase shift signal rp1 and local differential signals lb1 and lb
1'is multiplied by the multiplier 514 to obtain multiplication signals mo1 and mo.
1 ', and the reception phase shift signal rp2 and the local differential signal l
b2, lb2 'are multiplied by a multiplier 515 to obtain a multiplication signal m
o2 and mo2 '. Multiplication signals mo1 and mo at this time
1'and mo2 and mo2 'are shown in the following equations.

[0204] multiplied signal _{mo1 = {cos (ω L t} + ω I t + π / 2) + cos (ω L t-ω I t + π / 2)} * cos (ω L t) +1/2 { cos (2ω _L t + ω _I t + π) +1} * 1/2 {cos (2ω _L t) +1} = 1/2 {cos (ω _I t + π / 2) + cos (2ω _L t + ω _I t + π / 2) + cos (ω _I t + π / 2) + cos (2ω _L t-ω _I t + π / 2)} + 1/4 {1/2 [cos (ω _I t + π) + cos (4ω _L t + ω _I t + π)] + cos (2ω _L t + ω _I t + π) + cos (2ω _L t) +1} (6-22) Multiplied signal mo1 ′ = {cos (ω _L t + ω _I t + π / 2) + cos (ω _L t-ω _I t + π / 2)} * cos (ω _L t + π) +1/2 {cos (2ω _L t + ω _I t + π) +1} * 1/2 {cos (2ω _L t) +1} = 1/2 {cos (ω _I t-π / 2) + cos (2ω _L t + ω _I t -π / 2) + cos (ω _I t + π / 2) + cos (2ω _L t-ω _I t-π / 2)} + 1/4 {1/2 [cos (ω _I t + π) + cos (4ω _L t + ω _I t + π)] + cos (2ω _L t + ω _I t + π) + cos (2ω _L t) +1}… (6-23) Multiplication signal mo2 = {cos (ω _L t + ω _I t) + cos (ω _L t-ω _I t)} * cos (ω _L t) +1/2 {cos (2ω _L t + ω _I t) +1} * 1/2 {cos (2ω _L t) +1} = 1/2 {cos (ω _I t) + cos (2ω _L t + ω _I t) + cos (ω _I t) + cos (2ω _L t-ω _I t)} + 1/4 {1/2 [cos (ω _I t) + cos (4ω _L t + ω _I t)] + cos (2ω _L t + ω _I t) + cos (2ω _L t) +1}… (6 -24) Square Signal _{mo2 '= {cos (ω L} t + ω I t) + cos (ω L t-ω I t)} * cos (ω L t + π) +1/2 {cos (2ω L t + ω I t ) +1} * 1/2 {cos (2ω _L t) +1} = 1/2 {cos (ω _I t-π) + cos (2ω _L t + ω _I t + π) + cos (ω _I t + π) + cos (2ω _L t-ω _I t + π)} + 1/4 {1/2 [cos (ω _I t) + cos (4ω _L t + ω _I t)] + cos (2ω _L t _{+ ω I t) + cos (} 2ω L t) +1} ... (6-25) the received phase signals rp1 and the local differential signal lb1, lb
The multiplication signals mo1 and mo1 ′ with 1 ′ are subtractively combined by the subtractor 436, and the reception phase shift signal rp2 and the local differential signal l
The multiplication signals mo2 and mo2 ′ with b1 and lb1 ′ are subjected to subtraction synthesis in the subtractor 437, and subtraction signals so1 and s are obtained.
O2 is obtained. These subtracted signals so1 and so2 are shown in the following equations.

Subtraction signal so1 = cos (ω _I t + π / 2) + cos (2ω _L t + ω _I t + π / 2) + cos (ω _I t-π / 2) + cos (2ω _L t- ω _I t + π / 2) (6-26) Subtraction signal so2 = cos (ω _I t) + cos (2ω _L t + ω _I t) + cos (ω _L t) + cos (2ω _I t-ω _I t) (6-27) As is clear from these equations (6-26) and (6-27), the second harmonic of the phase shift signal of the half image signal and the second harmonic of the local differential signal The signal component generated by the multiplication with and is canceled.

Next, the subtracted signals so1 and so2 are π / 2.
The phase shift combiner 439 gives a relative phase difference of π / 2, and then they are added and combined. However, here, it is assumed that the subtraction signal so1 is advanced by π / 2 for subtraction synthesis. The synthetic signal obtained by this subtractive synthesis is shown in the following equation.

Composite signal = {cos (ω _I t + π) + cos (2ω _L t + ω _I t + π) + cos (ω _I t) + cos (2ω _L t-ω _I t + π)}- {cos (ω _I t) + cos (2ω _L t + ω _I t) + cos (ω _I t) + cos (2ω _L t-ω _I t)} = 2cos (ω _I t + π) + cos (2ω _L t + ω _I t + π) + cos (2ω _L t-ω _I t + π) (6-27) As is apparent from the equation (6-27), the image signal component is canceled.

In the above description, the subtraction signal so1 is advanced by π / 2 in the π / 2 phase shift combiner 439 to perform addition synthesis, but the same result can be obtained when the subtraction signal so1 is delayed by π / 2. Is obtained.

Further, when the local frequency is higher than the desired frequency, the π / 2 phase shift combiner 439 is caused to perform a phase shift opposite to that when the local frequency is lower than the desired frequency, or addition or subtraction synthesis is performed. By synthesizing in the opposite manner to the case where the local frequency is lower than the desired frequency, the image signal component and the half image signal component are canceled in the same manner as in the above configuration.

That is, according to the configuration of the first modified example, the reception RFs of two systems to which the relative phase difference of π / 2 is given.
The signal is multiplied by the local signal by the multipliers 514 and 515, respectively, and the multiplication output is π / 2 by the phase shift combiner 439.
Since the phase difference of / 2 is given and the signals are added and synthesized, the image signal component is surely canceled.

On the other hand, the differential conversion distributor 422 generates two systems of differential local signal pairs each having a phase difference of π, and these differential local signal pairs are received by the multipliers 514 and 515, respectively. The RF signal is multiplied, and subtraction synthesis is performed in subtractors 436 and 437 between the multiplication output pairs. For this reason, the half image signal components generated by the coupling of the second harmonics of the received RF signal and the local signal in the multipliers 614 and 615 are reliably canceled.

Therefore, also in the circuit of this modified example, it is possible to cancel both the image signal component and the half image signal component to obtain the received intermediate frequency signal consisting of only the desired wave signal.

(Second Modification) In the circuit shown in FIG. 40, the differential reception RF signal is converted into a differential reception RF signal pair having a phase difference of π in the differential conversion distributor 412, and then the differential reception RF signal is converted. Two pairs of differential local signal pairs rb1 and r
b 1 ′ and rb 2, rb 2 ′ and input to the multipliers 614 and 615, respectively, and the received local signal is received by the π / 2 phase shift distributor 623 in two systems having a relative phase difference of π / 2. The signals lp1 and lp2 are phase-shifted / distributed and input to the multipliers 514 and 515, respectively.
Then, the received local signals lp1 and lp2 of the above two systems
And two differential reception RF signal pairs rb1, rb1 'and rb2, rb2' are multiplied by the multipliers 614, 615.

With such a structure, when the local frequency is lower than the desired frequency, the cancel operation of the half image signal component and the image signal component is performed as follows.

The received RF signal (desired signal), the image signal and the half image signal input from the RF signal input terminal 410 are cos (ω _L t + ω _I t) cos (ω _L t-ω _I t) cos ( ω _L t + 1/2 ω _I t), these received input signals are input to the differential conversion distributor 41.
The received differential signals rb1, rb1 ', rb2, rb2' of two systems each having a relative phase difference of π are converted by 2 and then input to the multipliers 614, 615. The received differential signals rp1 and rp2 at this time are shown in the following equations.

Received differential signal rb1 = cos (ω _L t + ω _I t) + cos (ω _L t-ω _I t) + cos ² (ω _L t + 1/2 ω _I t) = cos (ω _L t + ω _I t) + cos (ω _L t-ω _I t) +1/2 {cos (2ω _L t + ω _I t) +1} (6-28) Received differential signal rb1 ′ = cos ( ω _L t + ω _I t + π) + cos (ω _L t-ω _I t + π) + cos ² (ω _L t + 1/2 ω _I t + π) = cos (ω _L t + ω _I t + π) + cos (ω _L t-ω _I t + π) +1/2 {cos (2ω _L t + ω _I t) +1} (6-29) Received differential signal rb2 = cos (ω _L t + ω _I t) + cos (ω _L t-ω _I t) + cos ² (ω _L t + 1/2 ω _I t) = cos (ω _L t + ω _I t) + cos (ω _L t- ω _I t) +1/2 {cos (2ω _L t + ω _I t) +1} (6-30) Received differential signal rb2 ′ = cos (ω _L t + ω _I t + π) + cos ( ω _L t-ω _I t + π) + cos ² (ω _L t + 1/2 ω _I t + π) = cos (ω _L t + ω _I t + π) + cos (ω _L t-ω _I t + π) +1/2 {cos (2ω _L t + ω _I t) +1} (6-31) On the other hand, the local signal input from the Lo signal input terminal 420 is a π / 2 phase shift distributor 623. 2 local phase shift signals lp1 and lp2 having a relative phase difference of π / 2
Are input to the multiplications 614 and 615. However, here, one of the local signals lp1 is π / 2.
It is assumed that the other local signal lp2 is generated by advancing. At this time, the local phase shift signal lp1,
lp2 is shown in the following equation. Where cos ² (ω _L t + π / 2) and
cos ² (ω _L t) is the phase-shifted signal cos obtained by phase-shifting the local signal
It is the second harmonic of (ω _L t + π / 2) and cos (ω _L t).

Local phase shift signal lp1 = cos (ω _L t + π / 2) + cos ² (ω _L t + π / 2) = cos (ω _L t + π / 2) +1/2 {cos (2ω _L t + π) +1} (6-32) Local phase shift signal lp2 = cos (ω _L t) + cos ² (ω _L t) = cos (ω _L t) +1/2 {cos (2ω _L t) +1} (6-33) In the multiplier 614, the received differential signals rb1, rb1 '
And the local phase shift signal lp1 are multiplied to obtain a multiplication signal mo
1, mo1 ', and the multiplier 615 multiplies the received differential signals rb1, rb1' and the local phase shift signal lp2 into the multiplication signals mo2, mo2 '. The multiplication signals mo1, mo1 'and mo2, mo2' at this time are shown in the following equations.

Multiplication signal mo1 = {cos (ω _L t + ω _I t) + cos (ω _L t-ω _I t)} * cos (ω _L t + π / 2) +1/2 {cos (2ω _L t + ω _I t) +1} * 1/2 {cos (2ω _L t + π) +1} = 1/2 {cos (ω _I t-π / 2) + cos (2ω _L t + ω _I t + π / 2) + cos (ω _I t + π / 2) + cos (2ω _L t-ω _I t + π / 2)} + 1/4 {1/2 [cos (ω _I t-π) + cos (4ω _L t + ω _I t + π)] + cos (2ω _L t + ω _I t) + cos (2ω _L t + π) +1}… (6-34) Multiplied signal mo1 ′ = {cos ( ω _L t + ω _I t + π) + cos (ω _L t-ω _I t + π)} * cos (ω _L t + π / 2) +1/2 {cos (2ω _L t + ω _I t) +1} * 1/2 {cos (2 ω _L t + π) +1} = 1/2 {cos (ω _I t + π / 2) + cos (2ω _L t + ω _I t-π / 2) + cos (ω _I t-π / 2) + cos (2ω _L t-ω _I t-π / 2)} + 1/4 {1/2 [cos (ω _I t + π) + cos (4ω _L t + ω _I t + π)] + cos (2ω _L t + ω _I t) + cos (2ω _L t + π) +1}… (6-35) Multiply signal mo2 = {cos (ω _L t + ω _I t) + cos (ω _L t-ω _I t)} * cos (ω _L t) +1/2 {cos (2ω _L t + ω _I t) +1} * 1/2 {cos (2ω _L t) +1} = 1/2 {cos (ω _I t) + cos (2ω _L t + ω _I t) + cos (ω _I t) + cos (2ω _L t-ω _I t)} +1/4 {1 / 2 [cos (ω _I t) + cos (4ω _L t + ω _I t)] + cos (2ω _L t + ω _I t) + cos (2ω _L t) +1}… (6-36) Multiply signal m o2 ′ = {cos (ω _L t + ω _I t + π) + cos (ω _L t-ω _I t + π)} * cos (ω _L t) +1/2 {cos (2ω _L t + ω _I t) +1} * 1/2 {cos (2ω _L t) +1} = 1/2 {cos (ω _I t + π) + cos (2ω _L t + ω _I t + π) + cos (ω _I t-π) + cos (2ω _L t-ω _I t + π)} + 1/4 {1/2 [cos (ω _I t) + cos (4ω _L t + ω _I t)] + cos (2ω _{L t + ω I t) + cos} (2ω L t) +1} ... (6-37) then, the multiplied signal MO1, MO1 'is subtracted synthesized by the subtractor 436, the subtraction signal so1 is obtained. Further, the multiplication signals mo2 and mo2 ′ are similarly subjected to subtraction synthesis by the subtractor 437, and the subtraction signal so2 is obtained. These subtracted signals so1 and so2 are shown in.

Subtraction signal so1 = cos (ω _I t-π / 2) + cos (2ω _L t + ω _I t + π / 2) + cos (ω _I t + π / 2) + cos (2ω _L t- ω _I t + π / 2) (6-38) Subtraction signal so2 = cos (ω _I t) + cos (2ω _L t + ω _I t) + cos (ω _L t) + cos (2ω _L t-ω _I t) (6-39) As is clear from these equations (6-38) and (6-39), the second harmonic of the differential conversion signal of the half image signal and the second harmonic of the local phase shift signal. The signal component generated by the multiplication with the wave is canceled.

Next, the subtracted signals so1 and so2 are π / 2.
The phase shift combiner 439 gives a relative phase difference of π / 2, and then they are added and combined. However, here, it is assumed that the subtraction signal so1 is delayed by π / 2 for subtraction synthesis. The synthetic signal obtained by this subtractive synthesis is shown in the following equation.

[0221] Synthesis signal _{= {cos (ω I t-} π) + cos (2ω L t + ω I t) + cos (ω I t) + cos (2ω L t-ω I t)} - {cos (ω _I t) + cos (2ω _L t + ω _I t) + cos (ω _I t) + cos (2ω _L t-ω _I t)} = 2cos (ω _I t-π)… (6-40) This ( As is clear from the equation (6-40), the image signal component is canceled. Thus, in the above configuration, the desired signal component is not canceled and the image signal component and the half image signal component are cancelled.

In the above description, the subtraction signal so1 is delayed by π / 2 in the π / 2 phase shift combiner 439 to perform subtraction synthesis, but the same result can be obtained when the subtraction signal so1 is advanced by π / 2. Is obtained.

When the local frequency is higher than the desired frequency, the π / 2 phase shift combiner 439 is caused to perform a phase shift opposite to that when the local frequency is lower than the desired frequency, or addition or subtraction synthesis is performed. By synthesizing in the opposite manner to the case where the local frequency is lower than the desired frequency, the image signal component and the half image signal component are canceled in the same manner as in the above configuration.

That is, according to this second modification, π
The two systems of local signals to which the relative phase difference of / 2 is given are multiplied by the received RF signal by the multipliers 614 and 615, respectively, and the multiplication output is calculated by the π / 2 phase shift synthesizer 439. Is added and then added and synthesized, the image signal component is reliably canceled.

On the other hand, the differential conversion distributor 412 generates two systems of differential reception RF signal pairs to which a phase difference of π is applied, and these differential reception RF signal pairs are respectively multiplied by multipliers 614 and 615. Is multiplied by the local signal, and subtraction synthesis is performed in subtractors 436 and 437 between the respective multiplication output pairs. Therefore, the half image signal component is surely canceled.

Therefore, also in the circuit of this modification, it is possible to cancel both the image signal component and the half image signal component to obtain the reception intermediate frequency signal consisting of only the desired wave signal.

(Third Modification) In the circuit shown in FIG. 41, after the received RF signal is differentially converted by the differential converter 712 into a differential received RF signal pair rb1, rb1 'having a relative phase difference of π. , The differential reception RF signal pair rb1 and rb1 ′ is π
2 having a relative phase difference of π / 2 in the phase shifter 713/2
System differential received RF signal pair rp1, rp1 'and rp
2, rp2 ′ and phase-shifted / distributed to multipliers 714,
715 and inputs the local signal to the distributor 72.
1 is distributed to the two systems of local signals ld1 and ld2 and input to the multipliers 714 and 715, respectively. Then, the differential reception RF signal pair rp1, rp1 'of the above two systems.
And rp2, rp2 'and two local signals ld
1 and ld2 are multiplied by each of the multipliers 714 and 715.

With such a configuration, when the local frequency is lower than the desired frequency, the cancel operation of the half image signal component and the image signal component is performed as follows.

The received RF signal (desired signal), the image signal and the half image signal input from the RF signal input terminal 410 are cos (ω _L t + ω _I t) cos (ω _L t-ω _I t) cos ( ω _L t + 1/2 ω _I t), these received input signals are first transmitted to the differential converter 71.
Received differential signal pair rb1, r having a relative phase difference of π at 2
converted to b1 '. This received differential signal pair rb1, rb
1'is shown in the following equation.

Received differential signal rb1 = cos (ω _L t + ω _I t) + cos (ω _L t-ω _I t) + cos ² (ω _L t + 1/2 ω _I t) = cos (ω _L t + ω _I t) + cos (ω _L t-ω _I t) +1/2 {cos (2ω _L t + ω _I t) +1} (6-41) Received differential signal rb1 ′ = cos ( ω _L t + ω _I t + π) + cos (ω _L t-ω _I t + π) + cos ² (ω _L t + 1/2 ω _I t + π) = cos (ω _L t + ω _I t + π) + cos (ω _L t-ω _I t + π) +1/2 {cos (2ω _L t + ω _I t) +1} (6-42) Then, the received differential signals rb1 and rb1 ′ Is input to a π / 2 phase shift distributor 713, where it is distributed / phase-shifted to two reception phase shift signal pairs rp1, rp1 ′ and rp2, rp2 ′ having a relative phase difference of π / 2. , Are input to the multipliers 614 and 615, respectively. However, here, it is assumed that the reception phase difference signal pair rp2, rp2 'is generated by advancing the reception differential signal pair rp1, rp1' by π / 2. The received phase shift signals rp1, rp1 'and rp2, rp2' at this time are shown in the following equations. Note that cos ² (ω _L t +
1/2 ω _I t + π / 2), cos ² (ω _L t + 1/2 ω _I t-π / 2),
cos ² (ω _L t + 1/2 ω _I t) and cos ² (ω _L t + 1/2 ω
_I t + π) is the phase-shifted signal cos (ω _L t + 1/2 ω _I t + π / 2), cos obtained by phase-shifting the differential conversion signal of the half image signal.
The second harmonic of (ω _L t + 1/2 ω _I t-π / 2), cos (ω _L t + 1/2 ω _I t) and cos (ω _L t + 1/2 ω _I t + π) It's a wave.

Received phase shift signal rp1 = cos (ω _L t + ω _I t + π / 2) + cos (ω _L t-ω _I t + π / 2) + cos ² (ω _L t + 1/2 ω _I t + π / 2) +1/2 {cos (2ω _L t + ω _I t + π / 2) +1} = cos (ω _L t + ω _I t + π / 2) + cos (ω _L t -ω _I t + π / 2) +1/2 {cos (2ω _L t + ω _I t + π) +1/2 {cos (2ω _L t-ω _I t + π / 2) +1}… ( 6-43) Received phase shift signal rp1 ′ = cos (ω _L t + ω _I t-π / 2) + cos (ω _L t-ω _I t-π / 2) + cos ² (ω _L t + 1 / 2 ω _I t-π / 2) +1/2 {cos (2ω _L t + ω _I t + π / 2) +1} = cos (ω _L t + ω _I t-π / 2) + cos (ω _L t-ω _I t-π / 2) +1/2 {cos (2ω _L t + ω _I t-π) +1/2 {cos (2ω _L t-ω _I t + π / 2) +1} (6-44) Received phase shift signal rp2 = cos (ω _L t + ω _I t) + cos (ω _L t-ω _I t) + cos ² (ω _L t + 1/2 ω _I t) +1 / 2 {cos (2ω _L t + ω _I t) +1} = cos (ω _L t + ω _I t) + cos (ω _L t-ω _I t) +1/2 {cos (2ω _L t + ω _I t) +1/2 {cos (2ω _L t + ω _I t) +1} (6-44) Received phase shift signal rp2 ′ = cos (ω _L t + ω _I t + π) + cos (ω _L t-ω _I t + π) + cos ² (ω _L t + 1/2 ω _I t + π) +1/2 {cos (2ω _L t + ω _I t) +1} = cos (ω _L t + ω _I t + π) + cos (ω _L t-ω _I t + π) +1/2 (cos (2ω _L t + ω _I t) _{+1/2 {cos (2ω L t +} ω I t) +1} ... (6-45) On the other hand, the local signal inputted from the Lo signal input terminal 420, the local distribution signal ld1 by distributor 721,
The two signals of ld2 are distributed to the multipliers 71, respectively.
4,715 is input. Local distribution signal l at this time
The following equation shows d1 and ld2.

Local distribution signal ld1 = cos (ω _L t) + cos ² (ω _L t) = cos (ω _L t) +1/2 {cos (2ω _L t) +1} (6-46) Local Distribution signal ld2 = cos (ω _L t) + cos ² (ω _L t) = cos (ω _L t) +1/2 {cos (2ω _L t) +1} (6-47) In the multiplier 714, The received phase shift signals rp1 and rp1 '
And the local distribution signal ld1 are multiplied to obtain a multiplication signal mo
1, mo1 ', and the multiplier 715 multiplies the received phase-shifted signals rp1, rp1' by the local distribution signal ld2 to obtain multiplication signals mo2, mo2 '. The multiplication signals mo1, mo1 'and mo2, mo2' at this time are shown in the following equations.

Multiplication signal mo1 = {cos (ω _L t + ω _I t + π / 2) + cos (ω _L t-ω _I t + π / 2)} * cos (ω _L t) +1/2 { _{cos (2ω L t + ω I} t + π) +1} * 1/2 {cos (2ω L t) +1} +1/2 {cos (2ω L t + ω I t + π / 2) +1 } * 1/2 {cos (2ω _L t) +1} = 1/2 {cos (ω _I t + π / 2) + cos (2ω _L t + ω _I t + π / 2) + cos (ω _I t-π / 2) + cos (2ω _L t-ω _I t + π / 2)} + 1/4 {1/2 [cos (ω _I t + π) + cos (4ω _L t + ω _I t + π)] + cos (2ω _L t + ω _I t + π) + cos (2ω _L t) +1} +1/4 {1/2 [cos (ω _I t + π / 2) + cos (4ω _L t + ω _I t + π / 2)] + cos (2ω _L t + ω _I t + π / 2) + cos (2ω _L t) +1}… (6-48) Multiplied signal mo1 ′ = {cos ( ω _L t + ω _I t-π / 2) + cos (ω _L t-ω _I t-π / 2)} * cos (ω _L t) +1/2 {cos (2ω _L t + ω _I t- π) +1} * 1/2 {cos (2ω _L t) +1} +1/2 {cos (2ω _L t + ω _I t + π / 2) +1} * 1/2 {cos (2ω _L t) +1} = 1/2 {cos (ω _I t-π / 2) + cos (2ω _L t + ω _I t-π / 2) + cos (ω _I t + π / 2) + cos (2ω _L t-ω _I t-π / 2)} + 1/4 {1/2 [cos (ω _I t-π) + cos (4ω _L t + ω _I t-π)] + cos (2ω _L t + ω _I t-π) + cos (2ω _L t) +1} +1/4 {1/2 [cos (ω _I t + π / 2) + cos (4ω _L t + ω _I t + π / 2) ] + cos (2ω _L t + ω _I t + π / 2) + cos (2ω _L t) +1}… (6-49) Arithmetic signal mo2 = {cos (ω _L t + ω _I t) + cos (ω _L t-ω _I t)} * cos (ω _L t) +1/2 {cos (2ω _L t + ω _I t) + 1} * 1/2 {cos (2ω _L t) +1} +1/2 {cos (2ω _L t + ω _I t) +1} * 1/2 {cos (2ω _L t) +1} = 1 / 2 {cos (ω _I t) + cos (2ω _L t + ω _I t) + cos (ω _I t) + cos (2ω _L t-ω _I t)} +1/4 {1/2 [cos ( ω _I t) + cos (4ω _L t + ω _I t)] + cos (2ω _L t + ω _I t) + cos (2ω _L t) +1} +1/4 {1/2 [cos (ω _I t) + cos (4ω _L t + ω _I t)] + cos (2ω _L t + ω _I t) + cos (2ω _L t) +1}… (6-50) Multiplication signal mo2 ′ = {cos (ω _L t + ω _I t + π) + cos (ω _L t-ω _I t + π)} * cos (ω _L t) +1/2 {cos (2ω _L t + ω _I t) +1} * 1 / 2 {cos (2ω _L t) +1} +1/2 {cos (2ω _L t + ω _I t) +1} * 1/2 {cos (2ω _L t) +1} = 1/2 {cos (Ω _I t + π) + cos (2ω _L t + ω _I t + π) + cos (ω _I t-π) + cos (2ω _L t-ω _I t + π)} + 1/4 {1 / 2 [cos (ω _I t) + cos (4ω _L t + ω _I t)] + cos (2ω _L t + ω _I t) + cos (2ω _L t) +1} +1/4 {1/2 [ cos (ω _I t) + cos (4ω _L t + ω _I t)] + cos (2ω _L t + ω _I t) + cos (2ω _L t) +1}… (6-51) Next, the multiplication signal The subtractors 436 subtractively synthesize mo1 and mo1 ′ to obtain a subtraction signal so1. Further, the multiplication signals mo2 and mo2 ′ are similarly subjected to subtraction synthesis by the subtractor 437 to obtain the subtraction signal so2. Subtraction signal so1,
so2 is shown in the following equation.

Subtraction signal so1 = cos (ω _I t + π / 2) + cos (2ω _L t + ω _I t + π / 2) + cos (ω _I t-π / 2) + cos (2ω _L t- ω _I t + π / 2) (6-52) Subtraction signal so2 = cos (ω _I t) + cos (2ω _L t + ω _I t) + cos (ω _L t) + cos (2ω _I t-ω _I t) (6-53) As is clear from these equations (6-52) and (6-53), the second harmonic of the differential conversion signal of the half image signal and the second harmonic of the local distribution signal. And the signal component generated by the multiplication of the second harmonic of the phase shift signal of the half image signal and the second harmonic of the local distribution signal are canceled.

Next, the subtracted signals so1 and so2 are π /
The signals are input to the 2-phase shift combiner 439, where a relative phase difference of π / 2 is given, and then they are added and combined. However, here, it is assumed that the subtraction signal so1 is advanced by π / 2 for subtraction synthesis. The obtained combined signal is shown in the following equation.

Composite signal = {cos (ω _I t + π) + cos (2ω _L t + ω _I t + π) + cos (ω _I t) + cos (2ω _L t-ω _I t + π)}- {cos (ω _I t) + cos (2ω _L t + ω _I t) + cos (ω _I t) + cos (2ω _L t-ω _I t)} = 2cos (ω _I t + π) +2 cos (2ω _L t + ω _I t + π) +2 cos (2ω _L t-ω _I t + π)} (6-54) As is apparent from the equation (6-54), the image signal component is canceled.

In the above description, the subtraction signal so1 is advanced by π / 2 in the π / 2 phase shift combiner 439 to perform subtraction synthesis, but the same result can be obtained even when the subtraction signal so1 is delayed by π / 2. Is obtained.

When the local frequency is higher than the desired frequency, the π / 2 phase shift combiner 439 is caused to perform a phase shift opposite to the phase shift when the local frequency is lower than the desired frequency, or addition or subtraction synthesis is performed. By synthesizing in the opposite manner to the case where the local frequency is lower than the desired frequency, the image signal component and the half image signal component are canceled in the same manner as in the above configuration.

That is, according to this third modification, π
In the / 2 phase shift distributor 713, the two differential reception RF signal pairs to which the relative phase difference of π / 2 is given are multiplied by the local signal by the multipliers 714 and 715, respectively, and the multiplication output is π / 2. Since the phase shift combiner 439 gives a relative phase difference of π / 2 and then performs addition combining, the image signal component is reliably canceled.

On the other hand, the differential converter 712 and the π / 2 phase shift distributor 713 generate two differential reception RF signal pairs to which a relative phase difference of π is given, and these differential reception RF signal pairs are generated. The pairs are respectively multiplied by the local signals in the multipliers 714 and 715, and the subtractor 4 is added between the respective multiplication output pairs.
Subtractive synthesis is performed at 36 and 437. Therefore, the half image signal component is surely canceled.

Therefore, also in the circuit of this modification, it is possible to cancel both the image signal component and the half image signal component to obtain the reception intermediate frequency signal consisting of only the desired wave signal.

[Seventh Embodiment] This embodiment is
A phase shift control circuit is newly provided, and depending on whether the local oscillation signal frequency is higher or lower than the desired signal frequency, the phase shift amount of the IF phase shift signal for obtaining the combined output signal or the local shift input to the multiplier. The phase shift amount of the phase signal is switched and controlled.

FIG. 42 is a circuit block diagram showing an example of the configuration of the frequency conversion circuit according to this embodiment. In the figure, the received RF signal input to the RF input terminal 1 is distributed to three systems by distributors 2 and 3, and three multipliers 9 and 10 each of which are a single balanced mixer (SBM) are provided. 11 is input. On the other hand, the reference local oscillation signal generated from the local oscillator 4 is distributed to the three systems by the distributors 5 and 6, and is then divided by ± π / 2 phase shifter 7 and +.
A relative phase difference of π / 2 is given by the π phase shifter 8, and these phase-shifted local oscillation signals are respectively output from the multiplier 9 and the multiplier 9.
Input to 10 and 11.

Each of the multipliers 9, 10, 11 multiplies the received RF signal by the local oscillation signal having a phase difference. And these multipliers 9, 1
Of 0 and 11, the multiplication outputs of the multipliers 9 and 11 are respectively passed through IF band pass filters (BPF) 12 and 14,
Here, after the signal component outside the IF band is attenuated, the adder 1
6, 17 are input. The multiplication output of the multiplier 10 is
After passing through an IF band pass filter (BPF) 13, the signal components outside the IF band are attenuated, and then the signal is distributed to 2 in the distribution 15.
It is distributed to the system and input to the adders 16 and 17.
In these adders 16 and 17, the above-mentioned multiplier 9 and
The multiplication output of 11 and the multiplication output of the multiplier 10 are added and combined.

Then, the addition outputs of the adders 16 and 17 are + π / 4 phase shifter 18a and −π / 4, respectively.
After a relative phase difference of π / 2 is given by the phase shifter 19a, the adder 20 performs addition synthesis. Then, the addition output of the adder 20 is output from the IF output terminal 21 as a reception intermediate frequency signal.

By the way, this frequency conversion circuit has a function of selectively generating the phase shift amounts of + π / 2 and −π / 2 as the phase shifter for supplying the local oscillation signal to the multiplier 10 as described above. The built-in ± π / 2 phase shifter 7 is used, and the control signal generator 2 for selectively controlling this phase shift amount is used.
2 is provided. The control signal generator 22 generates a switching control signal for selectively switching the phase shift amount generated by the phase shifter 10 according to whether the local oscillation signal frequency is higher or lower than the desired signal frequency. Is.

Next, the cancel operation of the image signal component and the IF / 2 image signal component by the circuit configured as described above will be described. First, the case where the local signal frequency is lower than the desired signal frequency will be described. RF
Received RF signal (desired signal) cos input to input terminal 1
(Ω _L t + ω _I t), image signal cos (ω _L t−ω _I
t) and the half image signal (IF / 2 image _{signals) cos (ω L t + 1} / 2ω I t) is the distributor 2,3 by first respectively after being distributed into three systems, the second and third multiplier It is input to 9, 10, and 11. Where ω
_L is each frequency of the local oscillation signal, and ω _I is each frequency of the IF signal. At this time, the received RF distribution signals rd1, rd2, rd3 input to the multipliers 9, 10, 11 are represented by the following equations.

Received RF distribution signals rd1, rd2, rd3 = cos (ω _L t + ω _I t) + cos (ω _L t−ω _I t) + cos ² (ω _L t + 1/2 ω _I t) = cos (ω _L t + ω _I t) + cos (ω _L t-ω _I t) +1/2 {cos (2ω _L t + ω _I t) +1}… (7-1) where cos ² _{(ω L t + 1 / 2ω} I t) is the second harmonic of half the image signal _{cos (ω L t + 1 /} 2ω I t).

On the other hand, the local signal lo generated from the local oscillator 4 is distributed by the distributors 5 and 6 to the three systems of local distribution signals lp1, ld2 and ld3. Then, of these, lp1 is directly supplied to the first multiplier 9 as a local phase shift signal. Also, ld3 is input to the + π phase shifter 8, where it is + π phase-shifted and the local phase shift signal lp3
And is supplied to the third multiplier 11.

By the way, since the local signal frequency is now lower than the desired signal frequency, the control signal generator 22 outputs ±
A control signal for selecting −π / 2 is applied to the π / 2 phase shifter 7. Therefore, the local distribution signal ld2 is shifted by −π / 2 in the ± π / 2 phase shifter 7 to become the local phase shift signal lp2, which is the second multiplier 1
0 is supplied. Here, the local phase shift signals lp1, lp2, lp supplied to the multipliers 9, 10, 11 respectively.
3, including its second harmonic, is expressed by the following equation.

Lp1 = cos (ω _L t) + cos ² (ω _L t) = cos (ω _L t) +1/2 {cos (2ω _L t) +1} (7-2) lp2 = cos ( ω _L t-π / 2) + cos ² (ω _L t-π / 2) = cos (ω _L t-π / 2) +1/2 {cos (2ω _L t-π) +1)}… ( 7-3) lp3 = cos (ω _L t + π) + cos ² (ω _L t-π) = cos (ω _L t + π) +1/2 {cos (2ω _L t) +1)}… ( 7-4) Now, in the first, second, and third multipliers 9, 10, and 11, the received RF distribution signals rd1, rd2, and rd are respectively received.
3 is multiplied by the local phase shift signals lp1, lp2, lp3. Then, of these, the first multiplier 9 outputs the multiplication signal mo1 shown in the following equation.

Mo1 = rd1 * lp1 = [cos (ω _L t + ω _I t) + cos (ω _L t−ω _I t)] * [cos (ω _L t)] + [1/2 {cos (2ω _L t + ω _I t) +1}] * [1/2 {cos (2 ω _L t) +1}] = 1/2 {cos (2ω _L t + ω _I t) + cos (ω _I t) + cos (2ω _L t-ω _I t) + cos (ω _I t)} +1/4 [1/2 {cos (4ω _L t + ω _I t) + cos (ω _I t) +1/4 { _{1 + cos (2ω L t)} + cos (2ω L t + ω I t)} ... (7-5) Then, the multiplied signal MO1 is a multiplied signal MO1 'passes through the IF band pass filter 12 . mo1 '= 1/2 * cos (ω I t) + 1/2 * cos (ω I t) + 1/8 * cos (ω I t) ... (7-6) Similarly, the second and third after being output from the multiplier 10 and 11, the multiplied signal passed through the band pass filter 13, 14 MO2 ', MO3' each mo2 '= 1/2 * cos (ω I t + π / 2) +1/2 * cos (ω _I t-π / 2) + 1/8 * cos (ω _I t + π)… (7-7) mo3 ′ ＝ 1/2 * cos (ω _I t-π) + 1/2 * cos (ω _I t + π) + 1/8 * cos (ω _I t) (7-8)

These multiplication signals mo1 ', mo2', m
Of o3 ′, mo1 ′ and mo3 ′ are as they are in the adder 1
6 and 17, the mo2 ′ is distributed into two systems by the distributor 15 and input to the adders 16 and 17.
In the adders 16 and 17, the multiplication signal mo
1 ', mo3' and mo2 'are added, and addition signals ao1 and ao2 shown in the following equation are output.

[0254]

(Equation 10)

As is clear from the equations (7-9) and (7-10), the addition signal ao output from the adders 16 and 17 is obtained.
1 and ao2 are signals in which the half image disturbing signal component is canceled.

Next, the added signals ao1 and ao2 are + π / 4 phase shifter 18a and −π / 4 phase shifter 19a, respectively.
To a phase difference of + π / 4 and −π / 4, respectively, to give a relative phase difference of π / 2, and the added signals are added to each other by the adder 20 and the added signal is added to the intermediate frequency signal. It is output from the IF signal output terminal 21 as IF-OUT. The + π / 4 and −π / 4 phase-shifted addition phase shift signals ip1 and ip2 and the intermediate frequency signal IF-OUT output from the adder 20 are represented by the following equation.

[0257]

[Equation 11]

As is clear from the equation (7-13), the addition output signals ao1 and ao2 of the adders 16 and 17 are converted to π by the + π / 4 phase shifter 18a and the −π / 4 phase shifter 19a.
After giving a relative phase difference of / 2, the adder 20 adds them to each other to cancel the image signal component.

Next, the operation when the local signal frequency is higher than the desired signal frequency will be described. At this time, the received RF distribution signal rd input to each of the multipliers 9, 10 and 11
1, rd2 and rd3 are represented by the following equations.

Received RF distribution signals rd1, rd2, rd3 = cos (ω _L t-ω _I t) + cos (ω _L t + ω _I t) + cos ² (ω _L t-1 / 2 ω _I t) = cos (ω _L t-ω _I t) + cos (ω _L t + ω _I t) +1/2 {cos (2ω _L t-ω _I t) +1}… (7-14) where cos ² _{(ω L t-1 / 2ω} I t) is the second harmonic of half the image signal _{cos (ω L t-1 /} 2ω I t).

On the other hand, the first and third multipliers 9 and 11 are supplied with the local phase shift signals lp1 and lp3 described in the expressions (7-2) and (7-4). However, when the local signal frequency is higher than the desired signal frequency, the control signal generation unit 22 gives the ± π / 2 phase shifter 7 a control signal for selecting + π / 2. Therefore, the second multiplier 10 is supplied with the local phase shift signal lp2 that is + π / 2 phase-shifted by the ± π / 2 phase shifter 7. The local phase shift signal lp2 at this time is shown in the following equation. lp2 = cos (ω _L t + π / 2) + cos ² (ω _L t + π / 2) = cos (ω _L t + π / 2) +1/2 {cos (2ω _L t + π) +1 )} (7-15) Therefore, the multiplication signals mo1, 'mo2', mo3 'output from the multipliers 9, 10, 11 and then passed through the intermediate frequency filters 12, 13, 14 are given by the following equations. become.

Mo1 ′ = 1/2 * cos (ω _I t) + 1/2 * cos (ω _I t) + 1/8 * cos (ω _I t) ... mo2 ′ = 1/2 * cos (ω _I t + π / 2) + 1/2 * cos (ω _I t-π / 2) + 1/8 * cos (ω _I t + π)… (7-17) mo3 ′ ＝ 1/2 * cos (ω _I t-π) + 1/2 * cos (ω _I t + π) + 1/8 * cos (ω _I t)… (7-18) These (7-16), (7-17), (7 -18) Equation (7-
As you can see by comparing with the formulas 6), (7-7), and (7-8),
By changing the amount of phase shift of the phase shifter 7 from −π / 2 to + π / 2, the multiplication signal mo output from the second multiplier 10 is changed.
2 has the same phase as when the local signal frequency is lower than the desired signal frequency, and therefore the addition signals ao1, ao2, + output from the adders 16 and 17 are obtained.
The IF phase shift signals ip and ip2 output from the π / 4 phase shifter 18a and the −π / 4 phase shifter 19a, and the adder 20.
The added combined output signal IF-out output from is the same signal as when the local signal frequency is lower than the desired signal frequency. Therefore, also in this case, both the image signal and the half image signal are canceled.

As described above, the local signal frequency is desired by switching the phase shift amount of the ± π / 2 phase shifter 7 by the control signal generator 22 according to whether the local signal frequency is higher or lower than the desired signal frequency. It is possible to cancel both the image signal and the half image signal in either case by forming a single common circuit without separately configuring circuits for cases where the frequency is higher and lower than the signal frequency. it can.

In addition, in the seventh embodiment, the following various modifications can be considered. (First Modification) FIG. 43 is a circuit block diagram showing a configuration of a frequency conversion circuit according to the first modification. In the figure, the same parts as those in FIG. 42 are designated by the same reference numerals, and detailed description thereof will be omitted.

In this modification, the phase shifter for generating the local phase shift signal supplied to the second multiplier 10 has a phase shift amount of −π / 2 fixed to −π / 2. I am using 7b. On the other hand, in the phase shifter for giving a relative phase difference of π / 2 to the added signals output from the adders 16 and 17, the phase shift amount can be switched between + π / 4 and −π / 4.
The π / 4 phase shifters 18b and 19b are used. Switching control of the amount of phase shift of these ± π / 4 phase shifters 18b and 19b is performed by a control signal generated from the control signal generator 22. The control signal generator 22 generates a control signal for selecting the phase shift amounts + π / 4 and −π / 4 depending on whether the local signal frequency is higher or lower than the desired signal frequency.

Next, the operation of this circuit will be described. In addition,
The operation when the local signal frequency is lower than the desired signal frequency is the same as the operation in FIG. 42 described above, so the operation when the local signal frequency is higher than the desired signal frequency will be described below.

In this case, the signals mo1 ', which are signals obtained by passing the multiplication signals mo1, mo2, mo3 output from the multipliers 9, 10, 11 through the IF band pass filters 12, 13, 14, respectively.
mo2 ′ and mo3 ′ are as follows.

Mo1 ′ = 1/2 * cos (ω _I t) + 1/2 * cos (ω _I t) + 1/8 * cos (ω _I t) (7-19) mo2 ′ = 1/2 * cos (ω _I t-π / 2) + 1/2 * cos (ω _I t + π / 2) + 1/8 * cos (ω _I t + π)… (7-20) mo3 ′ ＝ 1 / 2 * cos (ω _I t + π) + 1/2 * cos (ω _I t-π) + 1/8 * cos (ω _I t) (7-21) These multiplication signals mo1 ′, mo2 ′, Of the mo3 ′, the mo2 ′ is divided into two systems by the distributor 15 and input to the adders 16 and 17. Therefore, the adder 16,
17, the multiplication signals mo1 'and mo are respectively generated.
2'and the above mo2 'are added. Then, as a result of this addition, the adders 16 and 17 output addition signals ao1 and ao2, respectively, shown in the following equations.

[0269]

(Equation 12)

As is clear from these equations (7-22) and (7-23), the addition signals ao1 and ao2 mainly output from the adders 16 and 17 are signals in which the half image signal is canceled.

When the local signal frequency is higher than the desired signal frequency, the control signal generator 22
The amount of phase shift of the ± π / 4 phase shifter 18b is changed from + π / 4 to −π / 4.
And a control signal for switching the amount of phase shift of the ± π / 4 phase shifter 19b from −π / 4 to + π / 4.

Therefore, the addition signals ao1 and ao2 output from the adders 16 and 17 are ± π / 4 phase shifter 1 respectively.
In 8b and ± π / 4 phase shifter 19b, −
The phases are shifted by π / 4 and + π / 4, and a relative phase difference of π / 2 is given by this, and then they are added to each other by the adder 20. The addition phase shift signals ip1 and ip2 that have been phase-shifted by −π / 4 and + π / 4 and the intermediate frequency signal IF-OUT output from the adder 20 are represented by the following equation.

[0273]

(Equation 13)

As is clear from the equation (7-26), the addition output signals ao1 and ao2 of the adders 16 and 17 are supplied to the ± π / 4 phase shifter 18b and the ± π / 4 phase shifter 19b, respectively. The image signal components are canceled by adding −π / 4 and + π / 4 phase shifts to give a relative phase difference of π / 2, and then adding them together by the adder 20.

As described above, the control signal generator 2 determines the amount of phase shift of the ± π / 4 phase shifters 18b and 19b for IF phase shift depending on whether the local signal frequency is higher or lower than the desired signal frequency.
By switching according to 2, even if the local signal frequency is higher than or lower than the desired signal frequency, it is possible to configure a single common circuit without separately configuring circuits. Both half image signals can be canceled together.

(Second Modification) FIG. 44 is a circuit block diagram showing a structure of a frequency conversion circuit according to the second modification. Incidentally, in FIG.
The same parts as those in FIG.

In this modification, the adder 20 and the subtractor 23 are added to the arithmetic circuit for canceling the image signal component.
The adder 20 and the subtractor 23 are selectively switched by the switching control signal generated by the control signal generator 22 according to whether the local signal frequency is higher or lower than the desired signal frequency. It is a thing.

The operation of the circuit thus configured will be described. The operation when the local signal frequency is lower than the desired signal frequency is the same as the case of the circuit of FIG. 42 described above, and therefore the operation when the local signal frequency is higher than the desired signal frequency will be described below.

When the local signal frequency is higher than the desired signal frequency, the control signal generator 22 generates a switching control signal for turning off the adder 20 and turning on the subtractor 23. Therefore, the addition signals output from the adders 16 and 17 are + π / 4 phase shifters 18a and −π /, respectively.
In the 4-phase shifter 19a, + π / 4 and −π respectively
The phase is shifted by / 4, and a relative phase difference of π / 2 is given by this, and then the subtractors 23 add each other. Above + π /
4 and −π / 4 phase-shifted addition phase shift signals ip1 and ip
2 and the intermediate frequency signal IF− output from the subtractor 23
OUT is represented by the following equation.

[0280]

[Equation 14]

As is clear from the equation (7-29), the addition output signals ao1 and ao2 of the adders 16 and 17 are respectively supplied to the + π / 4 phase shifter 18a and the −π / 4 phase shifter 19a. The image signal components are canceled by performing + π / 4 and −π / 4 phase shifts to give a relative phase difference of π / 2, and then performing mutual addition by the subtractor 23.

As described above, the adder 20 and the subtractor 23 are provided in the arithmetic circuit for IF combination, and these adder 20
And the subtractor 23 are switched by the control signal generation unit 22 according to whether the local signal frequency is higher or lower than the desired signal frequency, whereby circuits are separately configured depending on whether the local signal frequency is higher or lower than the desired signal frequency. Even if it does not, it is possible to cancel both the image signal and the half image signal in both cases by forming one common circuit.

(Third Modification) FIG. 45 is a circuit block diagram showing a structure of a frequency conversion circuit according to the third modification. Incidentally, in FIG.
The same parts as those in FIG.

In this modification, the differential converter 2 is used as a phase shift circuit for supplying a local phase shift signal to the multipliers 9 and 11.
4, the output destinations of the non-inverted output signal and the inverted output signal output from the differential converter 24, that is, the multiplier 9
Or the multiplier 11 is switched by a switching control signal generated from the control signal generator 22.

The operation of the circuit thus configured will be described. The operation when the local signal frequency is lower than the desired signal frequency is the same as the case of the circuit of FIG. 42 described above, and therefore the operation when the local signal frequency is higher than the desired signal frequency will be described below.

When the local signal frequency is higher than the desired signal frequency, the first multiplier 9 is supplied with the phase-inverted signal of the local signal generated from the local oscillator 1, and the third multiplier 11 is supplied. Is supplied with a non-inverted signal of the local signal generated from the local oscillator 1, that is, as it is. In the second multiplier 10, the local signal generated from the local oscillator 1 is -π / 2 in the -π / 2 phase shifter 7b.
Two local phase shifted signals are provided. At this time, the local phase shift signals lp1, lp2, lp3 supplied to each of the multipliers 9, 10, 11 are expressed as follows, including their high harmonics.

Lp1 = cos (ω _L t + π) + cos ² (ω _L t + π) = cos (ω _L t + π) +1/2 {cos (2ω _L t) +1} (7- 30) lp2 = cos (ω _L t-π / 2) + cos ² (ω _L t-π / 2) = cos (ω _L t-π / 2) +1/2 {cos (2ω _L t-π) +1}… (7-31) lp3 = cos (ω _L t) + cos ² (ω _L t) ＝ cos (ω _L t) +1/2 {cos (2ω _L t) +1)}… (7 -32) Then, in each of the multipliers 9, 10 and 11, the reception RF distribution signals rd1, rd2 and rd3 of the three systems are respectively multiplied by the local phase shift signals lp1, lp2 and lp3 of the three systems. Therefore, at this time, each multiplier 9, 1
From 0 and 11, the following multiplication signals mo1 and m
o2 and mo3 are output. Note that only mo1 is shown here.

[0288] mo1 = rd1 * lp1 = [cos (ω L t-ω I t) + cos (ω L t + ω I t)] * [cos (ω L t)] + [1/2 {cos (2 ω _L t-ω _I t) +}] * [1/2 {cos (2ω _L t) +1}] = 1/2 {cos (2 ω _L t-ω _I t) + cos (ω _I t) + cos (2ω _L t + ω _I t + _I t) + cos (ω _I t)} +1/4 [1/2 {cos (4ω _L t-ω _I t) + cos (ω _I t)] +1 / 4 {1 + cos (2ω _L t) + cos (2ω _L t-ω _I t)} (7-33) Then, the multiplication signal mo1 of the equation (7-33) is passed through the IF band pass filter 12. was mo1 'is, mo1' = 1/2 * cos (ω I t) + 1/2 * cos (ω I t) + 1/8 * cos (ω I t) ... is (7-34). Similarly, the multiplication output signals mo of the multipliers 10 and 11
2, MO3 signal MO2 passed through a bandpass filter 13, 14 ', MO3' respectively, mo2 '= 1/2 * cos (ω I t + π / 2) + 1/2 * cos (ω I t- π / 2) + 1/8 * cos (ω _I t + π)… (7-35) mo3 ′ ＝ 1/2 * cos (ω _I t-π) + 1/2 * cos (ω _I t + π ) + 1/8 * cos ( ω I t) ... is (7-36).

As is clear from these equations (7-34), (7-35), and (7-36), the multiplication signals mo1 ', mo2', mo3 output from the multipliers 9, 10, 11 respectively. ′ Is equal to the equations (7-6), (7-7) and (7-8) obtained by the circuit shown in FIG. Therefore, this multiplication signal mo1 ′,
If the addition processing by the adders 16 and 17 below and the addition processing by the adder 20 after the phase shift by the + π / 4 phase shifter 18a and −π / 4 phase shifter 19a are performed using mo2 ′ and mo3 ′, The addition signals ao1 and ao obtained thereby
2, IF phase shift signals ip1 and ip2, combined addition output signal I
F-out becomes equal to the signal obtained when the local signal frequency is lower than the desired signal frequency in the circuit shown in FIG. 42, respectively, so that an intermediate frequency signal in which both the image signal and the half image signal are canceled is obtained. Will be done.

As described above, the differential converter 2 serves as a phase shift circuit for supplying the local phase shift signals to the multipliers 9 and 11.
4 is provided and the output destinations of the non-inverted output signal and the inverted output signal output from the differential converter 24 are switched by the control signal generation unit 22 according to whether the local signal frequency is higher or lower than the desired signal frequency. Even if the local signal frequency is higher and lower than the desired signal frequency, it is possible to configure both the image signal and the half image signal by forming one common circuit without separately configuring the circuits. Can be canceled together.

(Other Modifications) In all the configuration examples of the seventh embodiment described above, the sign of the phase shift of the IF phase shifters 18a, 18b and 19a, 19b is inverted, and the adder is further added. Even when 20 is replaced with the subtractor 23, both the image signal and the half image signal are canceled regardless of whether the local signal frequency is higher or lower than the desired signal frequency as in the above description. can do. FIG. 46 shows an example of the configuration in this case.

Similarly, in all the configuration examples of the seventh embodiment described above, when the local oscillation signal is below the desired signal, the local phase shift signal lp2 is π / 2 If the configuration has advanced the phase shift,
Both image signals and half image signals can be canceled.

[0293]

As described in detail above, according to the present invention,
It is possible to provide a frequency conversion circuit having an image rejection function capable of canceling out an interference wave component due to an image signal and an interference wave component due to a half image signal.

It is also possible to provide a frequency conversion circuit having an image rejection function, which does not require a narrow band filter or a large number of multiplication circuits, and which is suitable for integration and can achieve a simple and compact circuit structure. You can

Further, regardless of whether the local oscillation signal frequency is higher or lower than the desired signal frequency, a common circuit is provided without preparing a dedicated circuit, and the interference signal component by the image signal and the interference signal by the half image signal are generated. It is possible to provide a frequency conversion circuit having an image rejection function capable of canceling each component.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram showing an example of a configuration of a first embodiment of a frequency conversion circuit having an image rejection function according to the present invention.

FIG. 2 is a circuit block diagram showing a configuration of a frequency conversion circuit according to a first modification of the first embodiment.

FIG. 3 is a circuit block diagram showing a configuration of a frequency conversion circuit according to a second modification of the first embodiment.

FIG. 4 is a circuit block diagram showing a configuration of a frequency conversion circuit according to a third modification of the first embodiment.

FIG. 5 is a circuit block diagram showing a configuration of a frequency conversion circuit according to a fourth modification of the first embodiment.

FIG. 6 is a circuit block diagram showing an example of a configuration of a second embodiment of a frequency conversion circuit according to the present invention.

FIG. 7 is a circuit block diagram showing a configuration of a frequency conversion circuit according to a first modification of the second embodiment.

FIG. 8 is a circuit block diagram showing a configuration of a frequency conversion circuit according to a second modification of the second embodiment.

FIG. 9 is a circuit block diagram showing an example of a configuration of a frequency conversion circuit according to a third modification of the second embodiment.

FIG. 10 is a circuit block diagram showing a configuration of a frequency conversion circuit according to a fourth modification of the second embodiment.

11 is a vector diagram of a multiplication signal output from each multiplication circuit of the frequency conversion circuit shown in FIG.

12 is a vector diagram of a phase shift multiplication signal output from the IF phase shifter of the frequency conversion circuit shown in FIG.

13 is a vector diagram of an addition signal output from the IF addition circuit of the frequency conversion circuit illustrated in FIG.

FIG. 14 is a circuit block diagram showing an example of a configuration of a third embodiment of a frequency conversion circuit according to the present invention.

FIG. 15 is a circuit block diagram showing a configuration of a frequency conversion circuit according to a first modification of the third embodiment.

FIG. 16 is a circuit block diagram showing a configuration of a frequency conversion circuit according to a second modification of the third embodiment.

FIG. 17 is a circuit block diagram showing a configuration of a frequency conversion circuit according to a third modification of the third embodiment.

FIG. 18 is a circuit block diagram showing an example of the configuration of a fourth embodiment of a frequency conversion circuit according to the present invention.

FIG. 19 is a circuit block diagram showing a configuration of a frequency conversion circuit according to a first modification of the fourth embodiment.

FIG. 20 is a circuit block diagram showing a configuration of a frequency conversion circuit according to a second modification of the fourth embodiment.

FIG. 21 is a circuit block diagram showing a configuration of a frequency conversion circuit according to a third modification of the fourth embodiment.

FIG. 22 is a circuit block diagram showing a configuration of a frequency conversion circuit according to a fourth modification of the fourth embodiment.

FIG. 23 is a circuit block diagram showing an example of the configuration of a fifth embodiment of the frequency conversion circuit according to the present invention.

FIG. 24 is a circuit block diagram showing a configuration of a frequency conversion circuit according to a first modification of the fifth embodiment.

FIG. 25 is a circuit block diagram showing a configuration of a frequency conversion circuit according to a second modification of the fifth embodiment.

FIG. 26 is a circuit block diagram showing a configuration of a frequency conversion circuit according to a third modification of the fifth embodiment.

FIG. 27 is a circuit block diagram showing a configuration of a frequency conversion circuit according to a fourth modification of the fifth embodiment.

FIG. 28 is a circuit block diagram showing a configuration of a frequency conversion circuit according to a fifth modification of the fourth embodiment.

FIG. 29 is a circuit block diagram showing a configuration of a frequency conversion circuit according to a sixth modified example of the fourth embodiment.

FIG. 30 is a circuit block diagram showing a configuration of a frequency conversion circuit according to a seventh modified example of the fourth embodiment.

FIG. 31 is a circuit block diagram showing a configuration of a frequency conversion circuit according to an eighth modification of the fourth embodiment.

FIG. 32 is a circuit block diagram showing a configuration of a frequency conversion circuit according to a ninth modified example of the fourth embodiment.

FIG. 33 is a circuit block diagram showing an example of a configuration of a sixth embodiment of the frequency conversion circuit according to the present invention.

34 is a vector diagram of reception distribution signals of the frequency conversion circuit shown in FIG.

FIG. 35 is a vector diagram of local differential signals of the frequency conversion circuit shown in FIG. 33.

36 is a vector diagram of a local phase shift signal of the frequency conversion circuit shown in FIG.

37 is a vector diagram of a multiplication signal of the frequency conversion circuit shown in FIG. 33.

38 is a vector diagram of a subtraction signal of the frequency conversion circuit shown in FIG. 33.

FIG. 39 is a circuit block diagram showing a configuration of a frequency conversion circuit according to a first modification of the sixth embodiment.

FIG. 40 is a circuit block diagram showing a configuration of a frequency conversion circuit according to a second modification of the sixth embodiment.

FIG. 41 is a circuit block diagram showing a configuration of a frequency conversion circuit according to a third modification of the sixth embodiment.

FIG. 42 is a circuit block diagram showing an example of the configuration of the seventh embodiment of the frequency conversion circuit according to the present invention.

FIG. 43 is a circuit block diagram showing a configuration of a frequency conversion circuit according to a first modification of the seventh embodiment.

FIG. 44 is a circuit block diagram showing a configuration of a frequency conversion circuit according to a second modification of the seventh embodiment.

FIG. 45 is a circuit block diagram showing a configuration of a frequency conversion circuit according to a third modification of the seventh embodiment.

FIG. 46 is a circuit block diagram showing a configuration of a frequency conversion circuit according to another modification of the fifth embodiment.

FIG. 47 is a circuit block diagram showing an example of a configuration of a conventional frequency conversion circuit having an image rejection function.

FIG. 48 is a diagram showing a relationship between frequency spectra of a desired wave signal, a local oscillation signal, an image signal and a half image signal.

FIG. 49 is a circuit block diagram showing another example of the configuration of the frequency conversion circuit according to the third modification of the second embodiment.

[Explanation of symbols]

11a, 12a ... Mixer circuit 1, 101, 201, 301, 401 ... RF signal input terminal 2, 3, 5, 6, 15, 102-107, 204, 20
5,302,303,305,306,411,721
... Distributor or distribution circuit 9-11, 108-111, 211, 212, 261,
262,309-311,414,415,514,5
15, 614, 615, 714, 715 ... Multipliers 4, 112, 203, 304 ... Local oscillation circuit 20, 15-17, 113, 114, 241, 242,
291, 313, 314, 317 ... Adder 22 ... Control signal generator 23, 115, 243, 251, 252, 281, 28
2, 292, 321, 436.437 ... Subtractor 12-14, 116, 141-144, 206, 318
... IF band pass filter 117, 202, 319, 440 ... IF signal output terminal 7a, 7b, 8, 118-120, 146, 223, 2
24, 273, 274, 307, 308, 330-33
5, 423 ... Phase shifter for local oscillation signal 18a, 19a, 18b, 19b, 121, 145, 2
31, 232, 315, 316 ... Phase shifter for IF signal 220 ... Local oscillation signal generation circuit 221, 222, 271, 272 ... Differential output circuit 241, 251 ... Arithmetic circuit 270 ... Reception RF signal phase shift circuit 422 ... Differential conversion distributor 439 ... π / 2 phase shift combiner 513, 713 ... π / 2 phase shift distributor 24, 712 ... Differential converter

Claims (20)

[Claims] 1. A frequency conversion circuit having a function of multiplying a received radio high frequency signal by a local oscillation signal to convert it into an intermediate frequency signal and canceling image interference generated in the process, wherein the received radio high frequency signal First and second mixers for respectively multiplying the signals by two local oscillation signals having a relative phase difference of π / 2 and synthesizing respective multiplication outputs, and one of the output signals of the first and second mixers To π / 4
The phase shifter that shifts the phase and the output signal of one mixer that has been phase-shifted by this phase shifter and the output signal of the other mixer that is not phase-shifted are combined and the output is output as the intermediate frequency signal. A frequency conversion circuit having an image rejection function, which is provided with a synthesizing circuit. 2. The image rejection function according to claim 1, wherein each of the first and second mixers is provided with a band pass filter for removing a predetermined harmonic component from each multiplication output thereof. A frequency conversion circuit equipped. 3. The image according to claim 1, wherein the synthesizing circuit is provided with a bandpass filter on the output side for removing a predetermined harmonic component from the synthesized output.
Frequency conversion circuit with rejection function. 4. A frequency conversion circuit having a function of multiplying a received radio frequency signal by a local oscillation signal to convert it into an intermediate frequency signal, and canceling image interference generated in the process, a relative frequency of π / 2. A local oscillation signal generating means for generating a four-phase local oscillation signal having a phase difference, and a four-phase local oscillation signal generated by the local oscillation signal generating means for multiplying the received radio frequency signal by each. Π of the multiplication means and the multiplication outputs of the four systems obtained by this multiplication means
Π / 2 between multiplication outputs having a relative phase difference of / 2
Of the phase shift means for giving the relative phase difference of ## EQU1 ## and the multiplication outputs to which the relative phase difference of .pi. / 2 is given by the phase shift means, and then the synthesized outputs are further synthesized with each other to obtain the synthesized output. A frequency conversion circuit having an image rejection function. 5. A frequency conversion circuit having a function of multiplying a received radio frequency signal by a local oscillation signal to convert it into an intermediate frequency signal, and canceling image interference generated in the process, wherein the received radio frequency signal is received. Received signal phase shifting means for shifting the signals to generate four-phase wireless high-frequency signals having a relative phase difference of π / 2, and four-phase wireless high-frequency signals generated by the received-signal phase shifting means. Multiplying means for multiplying each by the local oscillation signal, and π of the four systems of multiplication outputs obtained by this multiplying means
Π / 2 between multiplication outputs having a relative phase difference of / 2
Of the phase shift means for giving the relative phase difference of ## EQU1 ## and the multiplication outputs to which the relative phase difference of .pi. / 2 is given by the phase shift means, and then the synthesized outputs are further synthesized with each other to obtain the synthesized output. A frequency conversion circuit having an image rejection function. 6. A frequency conversion circuit having a function of multiplying a received radio frequency signal by a local oscillation signal to convert it into an intermediate frequency signal, and canceling image interference generated in the process, a relative frequency of π / 2 A local oscillation signal generating means for generating a four-phase local oscillation signal having a phase difference, and a four-phase local oscillation signal generated by the local oscillation signal generating means for multiplying the received radio frequency signal by each. Π of the multiplication means and the multiplication outputs of the four systems obtained by this multiplication means
Π / between the first synthesizing means for synthesizing the multiplication outputs having the relative phase difference of / 2 and the respective synthesizing outputs obtained by the first synthesizing means.
The phase shift means for giving the relative phase difference of 2 and the synthesized output given the relative phase difference of π / 2 by the phase shift means are further synthesized with each other, and the synthesized output is used as the intermediate frequency signal. A frequency conversion circuit having an image rejection function, comprising a second synthesizing means for outputting. 7. A frequency conversion circuit having a function of multiplying a received radio frequency signal by a local oscillation signal to convert it into an intermediate frequency signal and canceling image interference generated in the process, wherein the received radio frequency signal is received. Received signal phase shifting means for shifting the signals to generate four-phase wireless high-frequency signals having a relative phase difference of π / 2, and four-phase wireless high-frequency signals generated by the received-signal phase shifting means. Multiplying means for multiplying each by the local oscillation signal, and π of the four systems of multiplication outputs obtained by this multiplying means
Π / between the first synthesizing means for synthesizing the multiplication outputs having the relative phase difference of / 2 and the respective synthesizing outputs obtained by the first synthesizing means.
A phase shift means for giving a relative phase difference of 2 and the combined outputs to which the relative phase difference of π / 2 is given by the phase shift means are further combined with each other, and the combined output is the intermediate frequency signal. And a second synthesizing means for outputting as a frequency conversion circuit having an image rejection function. 8. The local oscillation signal generating means divides a reference local oscillation signal into two, and two systems of local oscillation signals obtained by the distribution circuit are + π / 4 and −π / 4, respectively. A phase-shifting circuit that shifts the phase and a local-oscillation signal of the opposite phase are respectively generated based on the local-oscillation signals after the phase shift output from these phase-shifting circuits. 7. A frequency conversion circuit having an image rejection function according to claim 4 or 6, further comprising: a differential output circuit for outputting together with the local oscillation signal. 9. The reception signal generating means divides a received radio frequency high-frequency signal into two, and two systems of radio frequency high-frequency signals obtained by the distribution circuit are transferred by + π / 4 and −π / 4, respectively. Phase-shifting circuits that are in phase with each other, and radio-frequency high-frequency signals of opposite phases are generated based on the radio-frequency high-frequency signals after phase-shift output from these phase-shift circuits, respectively, and the radio-frequency high-frequency signals of the opposite phases are generated after the phase-shift 8. A frequency conversion circuit having an image rejection function according to claim 5, further comprising a differential output circuit for outputting together with a radio frequency signal. 10. The phase shift means is a means for giving a relative phase difference of π / 2 between the combined outputs obtained by the first combiner, and a predetermined first phase shift amount and the first phase shift amount. A phase shift circuit that selectively generates a second phase shift amount having a polarity opposite to the phase shift amount of, and the frequency of the local oscillation signal is higher or lower than the frequency of the received radio frequency signal. 8. The image according to claim 6, further comprising phase shift control means for switching control of the first and second phase shift amounts generated by the phase shift circuit of the phase shift means. -Frequency conversion circuit with a rejection function. 11. The local oscillation signal generating means are each π / 2.
As a means for generating a four-phase local oscillation signal having a relative phase difference of, a predetermined third phase shift amount and a fourth phase shift amount having a polarity opposite to the third phase shift amount are set. Phase shift means for selectively generating the phase shift means of the local oscillation signal generation means depending on whether the frequency of the local oscillation signal is higher or lower than the frequency of the received radio frequency signal. 3rd and 4th
7. A frequency conversion circuit having an image rejection function according to claim 4, further comprising a phase shift control means for switching and controlling the phase shift amount. 12. The reception signal phase shifting means is a means for shifting the received radio frequency signal to generate a radio frequency signal of four phases having a relative phase difference of π / 2. The phase shift amount and the fourth polarity which is opposite in polarity to the third phase shift amount.
And a phase shift circuit for selectively generating the phase shift amount of the received signal and the received signal phase shift means depending on whether the frequency of the local oscillation signal is higher or lower than the frequency of the received radio frequency signal. 8. A frequency having an image rejection function according to claim 5 or 7, further comprising phase shift control means for switching and controlling the third and fourth phase shift amounts generated by the phase shift circuit. Conversion circuit. 13. A radio frequency signal received by a frequency conversion circuit having a function of multiplying a received radio frequency signal by a local oscillation signal to convert the radio frequency signal into an intermediate frequency signal and canceling image interference generated in the process. And a local oscillation signal generating means for generating first, second and third local oscillation signals each having a phase difference of π / 2, and the signal distributing means First, second, and third multiplication means for multiplying the received three-system received radio frequency signals by the first, second, and third local oscillation signals generated by the local oscillation signal generation means, respectively. Of these multiplication means, a first and second multiplication means for synthesizing the multiplication outputs of the first and second multiplication means and the multiplication outputs of the third and second multiplication means, respectively. And the second
Between the synthesizing means and the synthesized output signals of these first and second synthesizing means.
A phase shift synthesizing means for synthesizing the synthesized output signals to which the phase difference has been given and then outputting the synthesized output to the intermediate frequency signal. Frequency conversion circuit with image rejection function. 14. A frequency conversion circuit having a function of multiplying a received radio frequency signal by a local oscillation signal to convert the radio frequency signal into an intermediate frequency signal and canceling image interference generated in the process. Differential conversion means for converting into a pair of differential local oscillation signals having a relative phase difference, and the pair of differential local oscillation signals obtained by the differential conversion means have a relative phase difference of π / 2. Π / 2 phase-shift distribution means for converting into two pairs of differential local oscillation signals, and two pairs of differential local-oscillation signals obtained by the π / 2 phase-shift distribution means and the received radio frequency signal. First and second for multiplying and respectively to output two systems of multiplication signal pairs
And the first and second synthesizing means for synthesizing each of the multiplication signal pairs obtained by the first and second multiplying means, and the first and second synthesizing means. An image rejection, comprising: a phase shift synthesizing unit for synthesizing each synthesized signal after giving a relative phase difference of π / 2 and outputting the synthesized signal as an intermediate frequency signal. Frequency conversion circuit with functions. 15. A frequency conversion circuit having a function of multiplying a received radio frequency signal by a local oscillation signal to convert it into an intermediate frequency signal and canceling image interference generated in the process, wherein the reception radio frequency signal is received. Π / 2 phase shifter / distributor for converting two to a radio high frequency signal having a relative phase difference of π / 2, and a local oscillation signal into a pair of differential local oscillation signals having a relative phase difference of π. After the conversion, the differential local oscillation signal pair is distributed into two systems, the differential conversion distribution means, the two-system radio high-frequency signals obtained by the π / 2 phase shift distribution means, and the differential conversion distribution. First and second multiplication means for respectively multiplying the two systems of differential local oscillation signal pairs obtained by the means to output two systems of multiplication signal pairs, and these first and second multiplication means Obtained by The first and second synthesizing means for synthesizing each of the multiplied signal pairs generated, and the relative phase difference of π / 2 are given to the respective synthetic signals obtained by the first and second synthesizing means. A frequency conversion circuit having an image rejection function, comprising: a phase shift synthesizing means for synthesizing and then outputting the synthesized signal as an intermediate frequency signal. 16. A frequency conversion circuit having a function of multiplying a received radio frequency signal by a local oscillation signal to convert the radio frequency signal into an intermediate frequency signal, and canceling image interference generated in the process. Differential conversion / distribution means for converting the differential reception signal pair into two systems after conversion into a pair of differential reception signals having a relative phase difference of π, and a local oscillation signal of a relative phase difference of π / 2. Π / 2 phase shift distribution means for converting to two systems of local oscillation signals, two systems of differential local oscillation signal pairs obtained by the differential conversion distribution means, and π / 2 phase shift distribution First and second multiplying means for multiplying the two systems of local oscillation signals obtained by the means and outputting a pair of multiplication signal pairs, and the first and second multiplying means. Each multiplication signal pair First and second synthesizing means for synthesizing each of the signals, and synthesizing the synthesized signals obtained by the first and second synthesizing means after giving a relative phase difference of π / 2, and A frequency conversion circuit having an image rejection function, comprising: a phase shift composition means for outputting a composite signal as an intermediate frequency signal. 17. A frequency conversion circuit having a function of multiplying a received radio frequency signal by a local oscillation signal to convert it into an intermediate frequency signal and canceling image interference generated in the process, Differential conversion means for converting into a pair of differential local oscillation signals having a relative phase difference, and the pair of differential local oscillation signals obtained by the differential conversion means have a relative phase difference of π / 2. Π / 2 phase-shift distribution means for converting into two pairs of differential local oscillation signals, and two pairs of differential local-oscillation signals obtained by the π / 2 phase-shift distribution means and the received radio frequency signal. First and second for multiplying and respectively to output two systems of multiplication signal pairs
And the first and second synthesizing means for synthesizing each of the multiplication signal pairs obtained by the first and second multiplying means, and the first and second synthesizing means. An image rejection, comprising: a phase shift synthesizing unit for synthesizing each synthesized signal after giving a relative phase difference of π / 2 and outputting the synthesized signal as an intermediate frequency signal. Frequency conversion circuit with functions. 18. The phase shift combination means is a means for providing a phase difference of π / 2 between the combined output signals of the first and second combination means, and a predetermined first phase shift amount and the first phase shift amount. Of the local oscillation signal, the frequency of the local oscillation signal being higher or lower than the frequency of the received radio frequency signal. 18. The phase shift control means for switching control of the first and second phase shift amounts generated by the phase shift means of the phase shift synthesizing means according to how the phase shift control means is provided. A frequency conversion circuit having the image rejection function described in (1). 19. The phase shift synthesizing means has an adding means and a subtracting means as means for synthesizing respective synthesized output signals given a phase difference of π / 2, and the frequency of the local oscillation signal is the received signal. 18. The combination control means for selectively switching between the addition means and the subtraction means of the phase shift combination means according to whether the frequency is higher or lower than the frequency of the wireless high frequency signal. A frequency conversion circuit having the image rejection function described in (1). 20. The local oscillation signal generating means are each π / 2.
As means for generating the first, second and third local oscillation signals having a phase difference of, a predetermined third phase shift amount and a fourth phase shifter having a polarity opposite to the third phase shift amount. Phase shift means for selectively generating a phase shift amount, and the local oscillation signal generation means of the local oscillation signal generation means depending on whether the frequency of the local oscillation signal is higher or lower than the frequency of the received radio frequency signal. Third and fourth phase shifting means occur
14. The frequency conversion circuit having an image rejection function according to claim 13, further comprising a phase shift control means for switching and controlling the phase shift amount of the above.