JP2002111389A - Semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor device which can be used for a downsized mixer having high image rejection. SOLUTION: This semiconductor device comprises a first and second even- harmonics mixers M1 and M2 which are composed of pairs of anti-parallel diodes while having a local oscillator terminal 11, intermediate frequency terminals 12 and 14, and high frequency terminals, a first filter F1 which is connected to the local oscillator terminal 11 of the first even-harmonics mixer M1 while having stubs S1 to S3, a capacitor C1, and a via hole V1, a second filter F2 which is connected to the local oscillator terminal 11 of the second even-harmonics mixer M2 while having stubs S4 to S6, a capacitor C2, and a via hole V2, a resistor R connected to the points equidistantly spaced from both via holes V1 and V2 of the first and second filters F1 and F2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a semiconductor device having an even harmonic mixer composed of an anti-parallel diode pair or the like.

[0002]

2. Description of the Related Art With the development of the communication field, the frequency range used has been widened, and high frequencies such as microwaves and millimeter waves have been used for communication purposes. MMIC is a key component of communication equipment using such high frequencies.
(Microwave Monolithic Inte
graded Circuit). MMIC is
HEMT (High Electron Mobili
ty Transistor) or MESFET (Met
al-Semiconductor FET), HBT
(Heterojunction Bipolar T
active devices having good characteristics for high frequencies such as Schottky junction diodes, and
Transmission line and MIM (Metal-Insulator-
Metal) Passive elements such as a capacitor and a resistor are collectively configured on a common circuit board.

One of high-frequency circuits incorporated in communication equipment, for example, a frequency converter, mixes an input signal and a local signal and converts it to a high-frequency output signal, or mixes an input signal and a local signal. Is used to convert to an intermediate frequency signal. The frequency converter handles low frequencies such as intermediate frequency signals to high frequencies such as input / output signals and local signals. Therefore, when the frequency conversion device is configured by the MMIC, the frequency of the local oscillation signal increases with the increase in the frequency of the input / output signal, and it is difficult to stably supply the local oscillation signal. For this reason, the frequency of the local oscillation signal becomes 1/1 / the actually required local oscillation frequency.
Attention has been paid to an even harmonic mixer that requires only two frequencies (hereinafter, this frequency is Lo), for example, a mixer having two mixer diodes connected in parallel with opposite polarities.

In the frequency converter, it is important to reduce leakage of an image signal generated at the time of frequency conversion to a signal terminal in order to reduce unnecessary frequency components included in an output signal. ing.

As a method of reducing the image signal, for example, there is a method of inserting a filter for removing the image signal before and after the mixer. In this method, since the structure of the filter is large, the entire circuit becomes large. Therefore, there is a method of using two mixers to reduce the size. This method
By keeping the phase relationship between the local oscillation signal and the intermediate frequency signal input to the two mixers constant, miniaturization becomes possible.

In this case, in order to realize a high image rejection ratio, it is required that the characteristics of the two mixers are uniform. If the MMIC technology is used, it is easy to form two mixers with small variations in characteristics on one chip, and a mixer having a high image rejection amount can be obtained.

Here, a conventional semiconductor device will be described with reference to FIG. 3 taking an image rejection mixer using an even harmonic mixer as an example.

In the figure, 31 is a local terminal to which a local signal is input, 32 is a signal terminal to which a high frequency signal is input or output, and 33 is a first intermediate frequency terminal to which a first intermediate frequency signal (I) is input or output. , 34 are the second intermediate frequency signals (Q)
Is a second intermediate frequency terminal for inputting or outputting. First
The intermediate frequency signal, (I) and the second intermediate frequency signal (Q) have the same amplitude and a phase difference of 90 °.

Reference numeral 35 denotes a first even harmonic mixer, 36 denotes a second even harmonic mixer, and 37 denotes a 90 ° hybrid. The first even harmonic mixer 35 and the second even harmonic mixer are respectively connected to two terminals 371 and 372 thereof. The wave mixer 36 is connected.
38 is another terminal 373 of the 90 ° hybrid 37
Is a terminating resistor of 50Ω. The signal terminal 32 is connected to another terminal 374 of the 90 ° hybrid 37.
Is connected.

A Wilkinson distributor 39 is connected to the local oscillation terminal 31 side of the first even harmonic mixer 35 and the second even harmonic mixer 36. The Wilkinson distributor 39 includes stubs S1 to S4, a resistor R, and the like.

F1 is a filter connected to the local oscillation terminal 31 side of the first even harmonic mixer 35, F2 is a filter connected to the local oscillation terminal 31 side of the second even harmonic mixer 36, and the filter F1 , F2 are open at the local frequency (Lo) and short-circuited at the high frequency of the high frequency signal. Here, the filters F1 and F2 are formed of stubs having a length of 波長 wavelength of a local oscillation frequency (Lo) used in a normal millimeter-wave band MMIC.

First and second even harmonic mixers 35, 3
Normally, a filter that is short-circuited at the local oscillation frequency (Lo) and open at the high-frequency frequency is provided between 6 and the 90 ° hybrid 37. Also, the first intermediate frequency terminal 33
A low-pass filter is usually provided between the first and second even harmonic mixers 35 and between the second intermediate frequency terminal 34 and the second even harmonic mixer 36. However, these filters and the low-frequency pass filter are omitted in FIG. 3 for convenience of explanation.

In the above configuration, the first and second even harmonic mixers 35 and 36 are supplied with intermediate frequency signals from the first and second intermediate frequency terminals 33 and 34, respectively. In addition, the local oscillator terminal 31 supplies a Wilkinson distributor 39.
Is supplied with a local oscillation signal (Lo).

The Wilkinson distributor 39 is connected to stubs S1, S2 having a length of 波長 wavelength of the local oscillation frequency (Lo) and having an impedance of √2 times the reference impedance, and stubs S1, S2. And a resistor R having a value twice as large as the reference impedance. The local oscillation signal is supplied to first and second even harmonic mixers 35 and 36 via a Wilkinson distributor 39. The outputs of the first and second even harmonic mixers 35 and 36 are combined by the 90 ° hybrid 37 and output to the signal terminal 32.

According to the above configuration, the first and second even harmonic mixers 35 and 36 are supplied with local oscillation signals having the same amplitude and the same phase, and output to the signal terminal 32 connected to the 90 ° hybrid 37. The image component is removed from the resulting signal.

In this case, in order to sufficiently suppress the image signal component, the first and second even harmonic mixers 35, 35
36, it is necessary that the amplitude and phase relations of the intermediate frequency signal and the local oscillation signal supplied to
It is desired that the characteristics of the diodes (not shown) used in the even harmonic mixers 35 and 36 of FIG. However, the input impedances of the first and second even harmonic mixers 35 and 36 as viewed from the input side of the local oscillation signal are different due to manufacturing variations and the like, and the first and second even harmonic mixers are different. The isolation between 35 and 36 may decrease.

However, when the Wilkinson distributor 39 is used, the energy generated by the difference between the input impedances of the first and second even harmonic mixers 35 and 36 is absorbed by the resistor R. Therefore, local signals having the same phase and the same amplitude are supplied to the first and second even harmonic mixers 35 and 36 with high accuracy.

[0018]

The image rejection mixer having the above configuration is an effective method for removing image signal components. However, local signals having the same amplitude and the same phase are converted into first and second even harmonic mixers 35 and 36.
, A Wilkinson distributor 37 is used.

The Wilkinson-type distributor 37 has two stubs S having a length of 波長 wavelength of the local oscillation frequency (Lo).
1, S2 is used. For this reason, the chip becomes large in the case where it is configured by the MMIC. In the Wilkinson distributor, resistors are connected to both ends of the two quarter-wavelength stubs S1 and S2. Therefore, in the case of the MMIC, two stubs S1,
The distance between the two stubs S1 and S2 and the resistance R
In many cases, parasitic lines S3 and S4 are provided to connect

Therefore, at high frequencies such as the millimeter wave band, the lengths of the parasitic lines S3 and S4 cannot be electrically neglected, and the first and second even harmonic mixers 35 and 36 cannot be ignored.
The isolation between them deteriorates. As a result, the amount of image rejection is reduced, and the effect of using the Wilkinson-type distributor is reduced (“Microstrip power combining circuit with neutralizing capacitor”: IEICE Transactions C. IVol. J80-C-). 1, No. 5, p
p24-245).

An object of the present invention is to provide a semiconductor device which solves the above-mentioned disadvantages and has a high image rejection amount and can obtain a small mixer.

[0022]

According to the present invention, there is provided a semiconductor device comprising:
A first and a second even harmonic mixer having a local oscillation terminal, an intermediate frequency terminal, and a high frequency terminal, each pair including an anti-parallel diode pair, and one end connected to the intermediate frequency terminal of the first even harmonic mixer. A connected first stub, a second stub having one end connected to the other end of the first stub, a third stub having one end connected to the other end of the second stub, and one end to the other end of the first stub And a first filter connected to the intermediate frequency terminal of the first even harmonic mixer, the first filter having a first capacitor grounded to the other end together with the other end of the third stub; A fourth stub having one end connected to the intermediate frequency terminal of the even harmonic mixer;
A fifth stub having one end connected to the other end of the stub;
A sixth stub having one end connected to the other end of the stub;
A second filter having a second capacitor having one end connected to the other end of the stub and the other end grounded with the other end of the sixth stub, and connected to the intermediate frequency terminal of the second even harmonic mixer; And a resistor connected between one end of the third stub of the first filter and one end of the sixth stub of the second filter.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION
A description will be given with reference to the circuit configuration diagram of FIG.

In the figure, reference numeral 11 denotes a local oscillator terminal to which a local oscillator signal is input. The local oscillation terminal 11 is divided into two, one of which is connected to the first even harmonic mixer M1. The first even harmonic mixer M1 is connected to a first intermediate frequency terminal 12 to which a first intermediate frequency signal is input or output, and the high frequency terminal of the first even harmonic mixer M1 is the It is connected to one terminal 131.

The other of the two local oscillator terminals 11 is connected to the second even harmonic mixer M2. A second intermediate frequency terminal 14 to which a second intermediate frequency signal is input or output is connected to the second even harmonic mixer M2, and a high frequency terminal of the second even harmonic mixer M2 is a 90 ° hybrid 13
Are connected to the second terminal 132.

Third terminal 133 of 90 ° hybrid 13
To the fourth terminal 134 of the 90 ° hybrid 13 is connected to a signal terminal 16 for inputting or outputting a high-frequency signal.

The first intermediate frequency signal input or output to the first even harmonic mixer M1 and the second intermediate frequency signal input or output to the second even harmonic mixer M2 have the same amplitude and the same phase. 90 ° different.

The first filter F1 is connected to the local oscillation terminal 11 side of the first even harmonic mixer M1, for example, to the first branch point P1.
Is connected to the local oscillation terminal 11 of the second even harmonic mixer M2.
The second filter F2 is connected to the side, for example, the second branch point P2.

The first filter F1 includes a first stub S1 connected to the first branch point P1, a second stub S2 connected to the first stub S1, a third stub S3 connected to the second stub S2, A common first via hole V grounding the other ends of the first capacitor C1, the third stub S3, and the first capacitor C1 connected between the first stub S1 and the second stub S2.
1, which is open at the local oscillation frequency (Lo) and short-circuited at the high frequency of the high frequency signal.

In the above configuration, the other ends of the third stub S3 and the first capacitor C1 are grounded by the common first via hole V1, but they may be grounded by different via holes.

The second filter F2 includes a fourth stub S4 connected to the second branch point P2, a fifth stub S5 connected to the fourth stub S4, a sixth stub S6 connected to the fifth stub S5, The second capacitor C2 connected between the fourth stub S4 and the fifth stub S5, the common second via hole V grounding the other ends of the sixth stub S6 and the second capacitor C2.
2, which are open at the local oscillation frequency (Lo) and short-circuited at the high frequency of the high frequency signal.

In the above configuration, the other end of the sixth stub S6 and the other end of the second capacitor C2 are grounded by the common second via hole V2, but may be grounded by different via holes.

Then, between the two stubs S2 and S3 of the first filter F1 and the two stubs S5 of the second filter F2,
A resistor R is connected between S6 and S6.

The length of the third stub S3 of the first filter F1 and the length of the sixth stub S6 of the second filter F2 are set to the same value, and from one end of the third stub S3 on the side to which the resistor R is connected. The length to the first via hole V1 and the length from one end of the sixth stub S6 on the side to which the resistor R is connected to the second via hole V2 are set to the same value.

Here, referring to FIG. 2, for the result of simulating the passing characteristic of the current flowing through the resistor R when the amplitude and phase of the signal are unbalanced at the first branch point P1 and the second branch point P2. I will explain. FIG.
(A) is a diagram in which portions of a first filter F1 and a second filter F2 of FIG. 1 are extracted, and portions corresponding to FIG. 1 are denoted by the same reference numerals, and redundant description is omitted.

At the first branch point P1 and the second branch point P2,
When the signals are applied in the same phase and the same amplitude, the signals applied to both ends of the resistor R also have the same phase and the same amplitude, and no current flows through the resistor R
No energy is consumed.

On the other hand, the first branch point P1 and the second branch point P
2 are not in phase and the same amplitude, the stubs S3 and S6 connected to the ground via holes V1 and V2 have a certain impedance. At this time, the signals applied to both ends of the resistor R are not in the same phase and the same amplitude, and the resistance R
Current flows through the resistor R, and the resistor R functions as an absorption resistor for absorbing imbalance in amplitude and phase.

When operating as a mixer, the first
The intermediate frequency signals having phases different from each other by 90 ° are applied to the second branch points P1 and P2. In this case, the intermediate frequency signal itself may be absorbed by the resistor R.

However, in general, the intermediate frequency is set to a frequency sufficiently lower than the local oscillation frequency (Lo). Therefore, if the length La of the stubs S3 and S6 connected between the ground via holes V1 and V2 and the resistor R is set to a length such that its impedance can be ignored at the intermediate frequency, the intermediate frequency of the resistor R Absorption of signal components is avoided.

The simulation results A to C shown in FIG.
Means that the value of the resistor R is 10Ω and the length La of the stubs S3 and S6 is La
Are 0, 50, and 100 μm, respectively, and show the passing characteristic of the current flowing through the resistor R due to the imbalance of the amplitude and phase of the signal applied between the first and second branch points P1 and P2.

In FIG. 2B, the horizontal axis represents the frequency, and the vertical axis represents the passing amount (S21) (dB). A passage amount (S21) of zero indicates that energy does not flow into the resistor R and does not function as an absorption resistor. La = 50, 10
In the case of 0 μm, the passing amount (S
21) increases, and it can be seen that energy is absorbed by the resistor R.

Therefore, if the length La of the stubs S3 and S6 is set to an appropriate value in accordance with the local oscillation frequency (Lo) in the configuration of FIG. Is hardly absorbed. On the other hand, at the local oscillation frequency (Lo) indicated by the symbol fL0,
If there is an imbalance in amplitude and phase, a circuit that absorbs the energy is formed.

Therefore, even when the characteristics of the diodes constituting the first and second even harmonic mixers M1 and M2 vary, the input impedance differs, and the isolation between the two deteriorates. A high volume mixer is realized.

In the case of the above-described configuration, the first and second filters are composed of a plurality of stubs and capacitors, and the first and second filters are equidistant from the first and second ground via holes. Is connected between the stubs of the filter. In this case, the first and second
Are all 1/4.
It can be formed of a stub having a length equal to or less than the wavelength.

According to the configuration described above, since the Wilkinson distributor is not used, deterioration of the isolation between the two even harmonic mixers unlike the case of using the Wilkinson distributor is prevented. A quarter-wavelength stub that constitutes a Wilkinson-type distributor is provided between two even-harmonic mixers and the Wilkinson-type distributor. For example, 1 of the local oscillation frequency (Lo)
Since a 波長 wavelength stub or the like is not used, the overall structure is reduced in size and the MMIC chip area is reduced.

[0046]

According to the present invention, a semiconductor device having a high image rejection amount and a small mixer can be realized.

[Brief description of the drawings]

FIG. 1 is a circuit configuration diagram for explaining an embodiment of the present invention.

FIG. 2 is a characteristic diagram for explaining an image rejection effect according to the present invention.

FIG. 3 is a circuit configuration diagram for explaining a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Local oscillation terminal 12 ... 1st intermediate frequency terminal 13 ... 90 degree hybrid 131-134 ... 90 degree hybrid 1st-4th terminal 14 ... 2nd intermediate frequency terminal 15 ... Terminating resistance 16 ... Signal terminal M1 ... 1st Even harmonic mixer M2 Second even harmonic mixer F1 First filter F2 Second filter S1 to S6 First to sixth stub C1 First capacitor C2 Second capacitor V1 First via hole V2 Second via hole R: Resistance P1: First branch point P2: Second branch point

Claims (4)

[Claims] 1. A first and a second even harmonic mixer having a local oscillation terminal, an intermediate frequency terminal, and a high frequency terminal and configured by an anti-parallel diode pair, and the intermediate of the first even harmonic mixer. A first stub having one end connected to the frequency terminal, and a second stub having one end connected to the other end of the first stub.
A stub, a third stub having one end connected to the other end of the second stub
A stub, a first capacitor having one end connected to the other end of the first stub and the other end grounded with the other end of the third stub, and connected to the intermediate frequency terminal of the first even harmonic mixer; The first filter, a fourth stub having one end connected to the intermediate frequency terminal of the second even harmonic mixer, and a fifth stub having one end connected to the other end of the fourth stub. A sixth capacitor having one end connected to the other end of the stub; a second capacitor having one end connected to the other end of the fourth stub and the other end grounded together with the other end of the sixth stub; A second filter connected to the intermediate frequency terminal of the even harmonic mixer, and a resistor connected between one end of the third stub of the first filter and one end of the sixth stub of the second filter. A semiconductor device comprising: 2. The semiconductor device according to claim 1, wherein the other end of the third stub, the other end of the first capacitor, the other end of the sixth stub, and the other end of the second capacitor are grounded via holes. 3. The semiconductor device according to claim 1, wherein the third stub and the sixth stub have the same length. 4. The length from one end of the third stub to which the resistor is connected to the via hole, and the length from one end of the sixth stub to which the resistor is connected to the via hole is the same. 13. The semiconductor device according to claim 1.