JP6430806B2 - Distributed mixer - Google Patents

Description

  The present invention relates to a distributed mixer that handles high-frequency electrical signals.

  Conventionally, a distributed mixer is known as a circuit configuration of a broadband mixer (for example, Non-Patent Document 1). The distributed mixer has a configuration in which a plurality of unit mixers each including a frequency conversion element formed of a transistor and a transmission line are connected in multiple stages (cascading connection). A distributed mixer has a broadband frequency conversion characteristic by forming a pseudo-line with a certain characteristic impedance (usually 50Ω) consisting of the capacitance of a transistor and the inductance of a transmission line. Each of the pseudo lines transmits a high frequency signal (hereinafter RF (Radio Frequency) signal), a local oscillation signal (hereinafter LO (Local Oscillator) signal), and an intermediate frequency signal (hereinafter IF (Intermediate Frequency) signal). There are tracks.

O. S. A. Tang and C. S. Aitchison, “A Practical Microwave Traveling-wave Mesfet Gate Mixer”, IEEE MTT-S Digest, 1985, pp.605-608

  In each pseudo line, a termination resistor is always arranged at a terminal opposite to a terminal to which each signal is input / output. Terminating resistors are necessary to make the impedance expected from the input / output terminals of the RF signal, LO signal, and IF signal to be a constant value (for example, 50Ω). Occur. In particular, the termination resistance of the IF signal line in the down-conversion mixer has a problem that the frequency conversion gain of the distributed mixer is lowered because most of the mixed IF signal is consumed by the termination resistance.

  The present invention has been made in view of this problem, and an object of the present invention is to provide a distributed mixer that solves the problem of reducing the frequency conversion gain by eliminating the power consumption caused by the terminating resistance of the IF signal transmission line.

The distributed mixer of the present invention includes a synthesizer that synthesizes a high-frequency signal and a local oscillation signal, a synthesized signal transmission line that transmits a synthesized signal synthesized by the synthesizer, and a terminal of the synthesized signal transmission line connected to a ground potential And N (N ≧ 2) common-source FETs that frequency-convert the combined signal of the combined signal transmission line into an intermediate frequency signal that is a difference between the high-frequency signal and the local oscillation signal. A unit mixer, and an intermediate frequency signal transmission line for transmitting the intermediate frequency signals output from the N unit mixers with one end serving as an intermediate frequency signal output terminal. The intermediate frequency signal transmission line includes one end at the intermediate frequency signal transmission line. The N transmission lines having the same electrical length, each having a frequency signal output terminal connected to the output of the N unit mixers at the other end, and the unit viewed from the intermediate frequency signal output terminal Each of the impedance of hexa is the impedance of the termination resistor is the N Kobai value, ends of the connected the transmission line to the output of the unit mixer is summarized in that the unterminated.

  According to the present invention, since the intermediate frequency signal transmission line (IF signal transmission line) is not provided with a termination resistor, it is possible to realize a distributed mixer that eliminates the power consumption that occurs and solves the problem of reduced frequency conversion gain. .

It is a figure which shows the structural example of the distribution mixer 100 of 1st Embodiment. It is a figure explaining a mode that IF signal is in-phase synthesized when it is assumed that termination resistor 9 is provided in IF signal transmission line 7 of distributed mixer 100. It is a figure which shows typically a mode that IF signal is totally reflected in X point of the distribution mixer 100. FIG. It is a figure which shows the example of the simulation result of the conversion gain of the distribution mixer. It is a figure which shows the structural example of the distribution mixer 200 of 2nd Embodiment. It is a figure which shows the equivalent circuit seen from the drain electrode of FET. It is a figure which shows the example of the simulation result of the conversion gain of the distribution mixer. It is a figure which shows the implementation example of IF signal transmission line of electrical length 0. It is a figure which shows the structural example of the distribution mixer 300 of 3rd Embodiment. It is a figure which shows the example of the simulation result of the conversion gain of the distribution mixer. FIG. 4 is a diagram showing a delay phase of a composite signal transmission line 4 of the distribution mixer 300. It is a figure which shows the structural example of the distribution mixer 400 of 4th Embodiment. It is a figure which shows the example of the simulation result of the conversion gain of the distribution mixer. It is a figure which shows the structural example of the distribution mixer 500 of 5th Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[First Embodiment]
FIG. 1 shows a configuration example of a distributed mixer 100 according to the first embodiment of the present invention. The distribution mixer 100 of this embodiment is a gate injection type distribution mixer. The distributed mixer 100 includes a combiner 3, a combined signal transmission line 4, a termination resistor 5, a plurality of unit mixers 6 a to 6 n, and an intermediate frequency signal transmission line (hereinafter referred to as IF signal transmission line) 7. Each of the unit mixers 6a to 6n is composed of a common source FET in this example. For each of the unit mixers 6a to 6n, for example, a field effect transistor (hereinafter referred to as FET) HEMT (High Electron Mobility Transistor) using a compound semiconductor material can be used.

  The combiner 3 generates a combined signal by combining the RF signal input to the RF terminal 1 and the LO signal input to the LO terminal 2. The synthesizer 3 is a general one such as a Wilkinson coupler or a diplexer.

  The combined signal including the RF signal and the LO signal is input to the gate electrodes of N (N ≧ 2) unit mixers 6 a to 6 n by the combined signal transmission line 4. A composite signal is input to the gate electrode of the unit mixer 6 a via the composite signal transmission line 4 a that constitutes the composite signal transmission line 4. The unit mixer 6a multiplies the RF signal and the LO signal included in the synthesized signal (that is, frequency-converts the RF signal) by the nonlinear characteristic of the transconductance of the FET, and generates an IF signal. The frequency of the IF signal is an absolute value of the difference between the frequency of the RF signal and the frequency of the LO signal.

  The combined signal is sequentially input via the combined signal transmission line 4 to the gate electrodes of the second and subsequent unit mixers 6b to 6n. The synthesized signal is transmitted to the gate electrode of the second stage unit mixer 6b via the synthesized signal transmission lines 4a and 4b, and the synthesized signal transmission lines 4a to 4n are sent to the gate electrode of the nth stage unit mixer 6n. Entered. Similarly to the unit mixer 6a, the second and subsequent unit mixers 6b to 6n also perform frequency conversion of the synthesized signal into an IF signal. The combined signal transmission line 4n for inputting the combined signal to the gate electrode of the n-th unit mixer 6n is connected to the terminating resistor 5 having one end connected to the ground potential (▽) via the combined signal transmission line 4p. .

  The drain electrode that is the output of the unit mixer 6a is connected to the drain electrode of the second stage unit mixer 6b via the IF signal transmission line 7a. The drain electrode of the second stage unit mixer 6b is connected to the drain electrode of the third stage unit mixer 6c (not shown) via the IF signal transmission line 7b. The drain electrode of the final stage (Nth) unit mixer 6n is connected to one end of the Nth IF signal transmission line 7n. The other end of the IF signal transmission line 7n forms an intermediate frequency signal output terminal (hereinafter referred to as IF terminal) 8 for outputting an IF signal to the outside.

  An end opposite to the IF terminal 8 which is one end of the IF signal transmission line 7 is an open end (point X). In the prior art distributed mixer, a termination resistor is connected to one end (X point) and the other end is connected to the ground potential. In this embodiment, since there is no termination resistor, no power is consumed by the termination resistor. Since the power consumed by the terminating resistor of the IF signal transmission line 7 is reflected at the open end (point X) and output from the IF terminal 8, the distributed mixer 100 can improve the frequency conversion gain.

  The distributed mixer 100 of the present embodiment eliminates the termination resistance arranged in the IF signal transmission line of the conventional distributed mixer and performs impedance matching of lumped constant design instead of distributed matching by the IF signal transmission line, The power consumption of the IF signal in the termination resistor is avoided and the conversion gain is improved. Performing lumped parameter impedance matching instead of distributed matching means that impedance matching is performed without particularly considering phase matching and reflected wave suppression.

  FIG. 2 shows a configuration example of the distributed mixer 100 in the case where the terminating resistor 9 of the IF signal transmission line 7 is provided. In this case, the end opposite to the IF terminal 8 of the drain electrode of the unit mixer 6a is connected to a termination resistor 9 having one end connected to the ground potential (▽) via the IF signal transmission line 7a-1. . Since the impedances when the IF terminal 8 side and the termination resistor 9 side are viewed from the drain electrode of the unit mixer 6a are equal, the IF signal output to the drain electrode of the unit mixer 6a is equally distributed between the termination resistor side and the IF terminal 8 side. Is done. The same applies to each of the unit mixers 6b to 6n.

Therefore, when the termination resistor 9 is present, about half of the IF signal output from each of the unit mixers 6 a to 6 n is consumed by the termination resistor 9. Further, only the traveling wave toward the IF terminal 8 output from each of the unit mixers 6a to 6n is synthesized in phase at the IF terminal 8. IF signal of the phase in the IF terminal 8, when the amount of phase delay in the transmission line of the one unit of the IF signal transmission line 7 and delta _IF the phase of the IF signal output of the first stage of the unit mixers 6a as 0, (N -1) In-phase synthesis is performed with a phase delay amount of _ΔIF . Here, N is the number (number of stages) of the unit mixers 6a to 6n.

  On the other hand, in the present embodiment without the termination resistor 9, the IF signal propagated to the opposite side of the IF terminal 8 as shown in FIG. 3 is totally reflected at the point X which is the open end and output from the IF terminal 8. become.

  For the purpose of confirming the effect of the present embodiment, a specific configuration of the distributed mixer 100 was determined as follows and a simulation was performed. The simulation conditions were such that the gate width of the FETs constituting the unit mixers 6a to 6n was 10 μm, the electrical length of the composite signal transmission line 4 was 0.1 at 100 GHz, and the characteristic impedance was 65Ω. The electrical length and characteristic impedance of the IF signal transmission line 7 are also the same as those of the synthetic signal transmission line 4. The number of unit mixer stages was set to eight.

  FIG. 4 shows the simulation results. The horizontal axis in FIG. 4 is the RF frequency [GHz], and the vertical axis is the conversion gain [dB]. The solid line in the figure is the conversion gain characteristic of this embodiment, and the broken line is the same characteristic of the conventional distributed mixer.

  The RF frequency was 90 GHz to 140 GHz, the LO signal frequency was 109 GHz, and the LO signal power was 5 dBm. There is a significant improvement in conversion gain at all RF frequencies. This is because, as described above, the power of the IF signal consumed by the terminating resistor in the prior art is reflected at the point X toward the IF terminal 8 and collected.

  Note that the conversion gain of the conventional distributed mixer is substantially constant regardless of the RF frequency. In contrast to this characteristic, the characteristic of the present embodiment shows a parabolic shape having a maximum value at an RF frequency of 110 GHz, and shows a characteristic in which the conversion gain decreases as the RF frequency moves away from 110 GHz. This indicates that since the LO signal is 109 GHz, the conversion gain decreases as the frequency of the IF signal having the absolute value of the difference between the RF signal frequency and the LO signal frequency increases. That is, in this embodiment, the conversion gain increases as the IF frequency decreases.

  The cause of the characteristics of the parabolic shape as described above is that the IF signal output from each of the unit mixers 6a to 6n is reflected to the IF terminal 8 after being totally reflected at the point X and directly to the IF terminal 8. This is probably because the phase of the incoming direct signal does not match as the frequency of the IF signal changes. A configuration for improving the decrease in conversion gain will be described in a third embodiment to be described later.

[Second Embodiment]
FIG. 5 shows a configuration example of the distribution mixer 200 of the second embodiment. The distributed mixer 200 includes a plurality of the same IF signal transmission lines 201 a having one end connected to each drain electrode of each of the unit mixers 6 a to 6 n and the other end being an IF terminal 8. That is, the IF terminal 8 is formed by connecting the drain electrodes of the unit mixers 6a to 6n in parallel through the IF signal transmission line 201a.

  The feature of this embodiment is that the conversion gain of the distributed mixer is improved by changing the distribution matching in the IF signal, which has been performed by the conventional distributed mixer, to the lumped parameter design. In the conventional distributed mixer, by using distributed matching, as described above, the following two conditions, that is, the impedance matching condition at the IF terminal 8 and the IF signal component output from each FET in the IF signal transmission line 7 are used. Can be simultaneously satisfied by the IF terminal 8.

  Also in the lumped constant design for the IF signal in the distributed mixer 200 according to the present embodiment, if the above two conditions are satisfied, the reflected wave at the IF terminal 8 is suppressed, and the conversion gain can be further improved. Hereinafter, it will be described that such a design is possible in a region where the IF signal frequency is low.

  Usually, in a down-conversion mixer for measuring instruments, a down-conversion mixer for radar, and the like, the lower limit of the IF signal frequency is DC (frequency 0), and the upper limit is a low frequency of about several MHz. When a matching circuit is created at such a low IF frequency, the size of the LC matching circuit using a quarter wavelength line becomes so large that it cannot be produced on-chip.

  When the IF signal frequency is low, it is difficult to create a normal LC matching circuit on-chip, but the problem of phase matching due to delay in the IF signal transmission line is alleviated. This is because when the IF signal frequency is low, the wavelength of the IF signal is sufficiently larger than the transmission line created on-chip, and the electrical length of the line connecting the FETs 6a to 6n of the distributed mixer 200 and the IF terminal 8 is the IF signal. This is because the IF signals output from the FETs 6a to 6n are synthesized at the IF terminal 8 in substantially the same phase.

  In view of this point, the distributed mixer 200 of the present embodiment provides a means for solving the problem of impedance matching at the IF terminal 8 which is a problem particularly at a low IF frequency. The means is not a conventional LC matching circuit, but pays attention to the output impedance viewed from the drain electrodes of the FETs 6a to 6n connected to the IF terminal 8, and sets the number of unit mixers constituting the distributed mixer 200 to a specific value. Thus, the impedance of the IF terminal 8 viewed from the mixer side is matched to 50Ω. The number of stages of unit mixers constituting the distributed mixer 200 of the present embodiment is determined by the following discussion.

  In FIG. 5, the output impedance of each FET of each of the unit mixers 6a to 6n is Zd. FIG. 6 shows an equivalent circuit viewed from the drain electrode of the FET. The output impedance Zd of the FET can be expressed by the following equation.

ここでＲｄはドレイン抵抗、Ｃｄはドレイン−ソース間容量である。一般にＣｄは、数fFと非常に小さいため、ＩＦ信号の周波数として用いられる数MHz以上の周波数においては、出力インピーダンスＺｄはＲｄに近似（Ｚｄ＝Ｒｄ）することができる。

Here, Rd is a drain resistance, and Cd is a drain-source capacitance. In general, since Cd is very small, such as several fF, the output impedance Zd can be approximated to Rd (Zd = Rd) at a frequency of several MHz or more used as the frequency of the IF signal.

  In FIG. 5, the entire output impedance of the unit mixers 6a to 6n viewed from the IF terminal 8 is connected in parallel by the number of stages of the distributed mixer. Therefore, if the number of unit mixer stages is N, the output impedance Zd viewed from the IF terminal 8 can be expressed as Zd = Rd / N.

  The impedance of each of the unit mixers 6a to 6n viewed from the IF terminal 8 is a value obtained by multiplying the impedance of the termination resistor 5 by N. If N is selected so that Rd / N = 50Ω, the impedance when the unit mixers 6a to 6n are viewed from the IF terminal 8 can be set to 50Ω, which is the same as that of the termination resistor 5.

  FIG. 7 shows a simulation result of the conversion gain characteristic of the distributed mixer 200 when Rd = 500Ω and N = 10. The horizontal and vertical axes in FIG. 7 are the same as those in FIG. Also, the simulation conditions are the same as in FIG.

  The conversion gain of the distributed mixer 200 of this embodiment is improved by about 2 dB at RF frequencies of 90 MHz and 130 GHz with respect to the characteristics of the distributed mixer 100 of the first embodiment. Also, a relatively flat characteristic is obtained with respect to fluctuations in the RF frequency.

  FIG. 8 shows an example of a method for sufficiently reducing the electrical length of the IF signal transmission line 7a. FIG. 8 is a diagram showing an example in which the unit mixers 6a to 6n are arranged in an annular shape on the chip when the distributed mixer 200 is integrated. The distance between the drain electrode of each of the unit mixers 6a to 6n and the IF terminal 8 can be shortened by arranging the drain electrodes of the unit mixers 6a to 6n in the center direction of the circle and the source electrode in the outer direction of the ring. . By integrally forming the drain regions of the plurality of unit mixers 6a to 6n, the electrical length of the IF signal transmission line 201a can be set to a sufficiently small value. The electrical length of the IF signal transmission line 201a in the range surrounded by the broken line in FIG. 8 is almost zero. In this way, the unit mixers 6a to 6n are arranged in an annular shape so that the electrical length of the IF signal transmission line 201a is close to zero in an ordinary integrated circuit process manufactured by a mask & etching process. I can do it.

[Third Embodiment]
FIG. 9 shows a configuration example of the distribution mixer 300 of this embodiment in which the unit mixers 6a to 6n of the distribution mixer 100 of the first embodiment have a cascode configuration. The cascode configuration is a vertically stacked circuit configuration.

  The distribution mixer 300 is a distribution mixer having a cascode mixer as a unit mixer. The cascode mixer which is a unit mixer has a configuration in which FETs 6a to 6n which are common source FETs and FETs 301a to 301n which are common gate FETs are vertically stacked. For example, the first-stage cascode unit mixer in the distribution mixer 300 has a configuration in which the drain electrode of the FET 6a, which is a common source FET, and the source electrode of the common gate FET 301a are connected (vertically stacked).

  The gate electrode of the common-gate FET 301a is biased to a predetermined voltage by the bias capacitor 302a and the bias resistor 303a. The predetermined voltage is a constant voltage that causes the grounded-gate FET 301a to operate in the saturation region.

  The second and subsequent cascode unit mixers are similarly configured. Other configurations of the distribution mixer 200 are the same as those of the distribution mixer 100 (FIG. 1).

  The common source FETs 6a to 6n of the distributed mixer 300 function as a mixer, and the vertically grounded gate FETs 301a to 301n function as mixed IF signal amplifiers. Therefore, a high conversion gain can be obtained.

  FIG. 10 shows an example of the simulation result of the conversion gain of the distributed mixer 300. The horizontal and vertical axes in FIG. 10 are the same as those in FIG.

  The frequencies of the RF signal and the LO signal were the same as the simulation conditions shown in FIG. Other simulation conditions are as follows. The gate width of each FET was 10 μm, the characteristic impedance of the synthetic signal transmission line 4 was 63Ω, and the electrical length was 0.2 at 100 GHz. The IF signal transmission line 7 has a characteristic impedance of 55Ω and an electrical length of 0.2 at 100 GHz. The number of unit mixers was four.

  The conversion gain of the distribution mixer 300 is improved by about 0.5 dB at the RF frequency = 110 GHz than the conversion gain of the distribution mixer 100 shown in FIG. However, like the distributed mixer 100, it exhibits a parabolic characteristic in which the conversion gain is reduced regardless of which frequency direction the RF frequency is centered on 110 GHz.

  This is because the termination resistor used in the IF signal transmission line 7 is eliminated, so that the portion becomes an open end (X point), and is reflected at the open end (X point) to reach the IF terminal 8. This is considered to be due to the phase difference between the signal and the IF signal that reaches the IF terminal 8 directly.

FIG. 11 shows a delay phase generated according to the number of stages of the cascode unit mixer through which the synthesized signal passes. The delay phases of the RF signal and the LO signal that pass through the cascode unit mixer are Φ _RF (1) and Φ _LO (1) because the propagated composite signal transmission line 4 is only in the section of the composite signal transmission line 4a. The delay phases of the RF signal and the LO signal passing through the nth stage cascode unit mixer (FET 6n and FET 301n) are Φ _RF (n) and Φ _LO (n). The phase Φ _IF (i) of the IF signal can be expressed by the following equation. i is the number of stages of the cascode type unit mixer.

ここで式（２）の符号は、ＲＦ信号の周波数の方がＬＯ信号の周波数よりも高い時に＋、その逆の時に−になる。本実施形態の分布ミキサ３００は、ゲート注入型であるので、ＲＦ信号とＬＯ信号は同じ合成信号伝送線路４を伝搬する。したがって、各カスコード型単位ミキサでのＲＦ信号とＬＯ信号の伝搬遅延位相をΔ_ＲＦとΔ_ＬＯと表現すれば、式（３）と式（４）が成立する。

Here, the sign of the expression (2) becomes + when the frequency of the RF signal is higher than the frequency of the LO signal, and becomes-when the frequency is opposite. Since the distributed mixer 300 of this embodiment is a gate injection type, the RF signal and the LO signal propagate through the same combined signal transmission line 4. Therefore, if the propagation delay phase representation and delta _RF and delta _LO of the RF and LO signals at each cascode unit mixer, equation (3) and (4) is satisfied.

したがって次式が成り立つ。

Therefore, the following equation holds.

ここで、Δ_ＩＦ＝Δ_ＲＦ−Δ_ＬＯである。

Here, Δ _IF = Δ _RF −Δ _LO .

  In this way, the IF signal output from each cascode unit mixer is output with a propagation phase delay expressed by Equation (4). Therefore, if a phase difference that cancels the phase difference of Equation (5) can be given to each cascode type unit mixer, the IF signal is matched in phase at the IF terminal 8, and a high conversion gain is obtained in a wide frequency range of the RF signal. It is thought that it is obtained.

  Next, a description will be given of a distributed mixer 400 according to the fourth embodiment in which a phase difference that cancels this phase difference is given.

[Fourth Embodiment]
In FIG. 12, the unit mixers 6a to 6n of the distributed mixer 200 of the second embodiment are configured as a cascode type unit mixer, and delay lines 401a to 401n are connected between the source grounded FETs 6a to 6n and the gate grounded FETs 301a to 301n. The structural example of the distribution mixer 400 of this embodiment which inserted 401m is shown. In FIG. 12, the notation of the bias resistors 303a to 303n is omitted.

  As shown in FIG. 12, if delay lines 401a to 401m are arranged between the common-source FETs 6a to 6n and the common-gate FETs 301a to 301n, the delay amount can be reduced in a state where each cascode unit mixer is isolated. Can be added.

If the number of stages of cascode unit mixers and N stage, from the cascode unit mixer i-th stage, than the first-stage cascode unit mixers (i-1) delta _IF only IF signal phase-rotation is output. Therefore, by setting the phase rotation quantity of the i-th stage of the delay line (N-i) delta _IF, each stage all phases of the IF signal output from the cascode unit mixer (N-1) a delta _IF Thus, the IF terminal 8 performs the same phase matching.

  FIG. 13 shows an example of the simulation result of the conversion gain of the distribution mixer 400 of this embodiment. The solid line is the characteristic of this embodiment, the alternate long and short dash line is the characteristic of the third embodiment, and the broken line is the characteristic of the conventional distributed mixer. The horizontal and vertical axes in FIG. 13 are the same as those in FIG. The simulation conditions are the same except that delay lines 401a to 401n are added.

  It can be seen that the characteristic of the conversion gain with respect to the change of the RF frequency indicated by the solid line is flatter than the characteristic of the third embodiment indicated by the one-dot chain line. In particular, the improvement range is large at 140 GHz, and the conversion gain of about 2 dB or more is improved.

[Fifth Embodiment]
The distributed mixers 100, 200, 300, and 400 of the first to fourth embodiments are all gate injection type distributed mixers. The idea shown in the above embodiment can also be applied to a source injection type distributed mixer.

  The source injection type mixer is a mixer that inputs a LO signal to a source electrode. In a normal source injection mixer, an RF signal is input to the gate electrode, an LO signal is input to the source electrode, and an IF signal is output from the drain electrode. By modulating the drain-source voltage and the gate-source voltage by the LO signal, the transconductance of the FET is modulated to perform the mixing operation. A configuration and effects when the source injection mixer having the above configuration is applied to this embodiment will be described.

  FIG. 14 shows a configuration example of a distribution mixer 500 of this embodiment in which the unit mixers 6a to 6n of the distribution mixer 200 of the second embodiment are of the source injection type. The distributed mixer 500 includes a high-frequency signal transmission line 501, a terminating resistor 5, source injection type unit mixers 506 a to 506 n, and a local oscillation signal distributor 502. In addition, the description of the same IF frequency signal transmission line 201a which connects between the drain electrode of each unit mixer 6a-6n and IF terminal 8 is abbreviate | omitted. Similarly to the distributed mixer 200, the distributed mixer 500 does not include a termination resistor for the intermediate frequency signal transmission line.

  The high frequency signal transmission line 501 transmits the high frequency signal input from the RF terminal 1 to the gate electrodes of the unit mixers 506a to 506n. The RF terminal 1 and the gate electrode of the first stage unit mixer 506a are connected by a high-frequency signal transmission line 501a.

  The configuration of the high-frequency signal transmission line 501, the terminating resistor 5, and each unit mixer 506 a to 506 n and the relationship between the drain electrode of each unit mixer 6 a to 6 n and the IF terminal 8 are as follows. This is the same as the above-described distributed mixer 200 except for the points.

  The LO signal input from the LO terminal 2 transmitted through the composite signal transmission line 4 in the distributed mixer 200 is input to the source electrode of each of the unit mixers 506a to 506n by the local oscillation signal distributor 502. The local oscillation signal distributor 502 inputs a predetermined bias voltage to the source electrodes of the unit mixers 506a to 506n simultaneously with the LO signal. The local oscillation signal distributor 502 is a general one.

  Also in the distributed mixer 500 configured as described above, an IF signal obtained by mixing the RF signal and the LO signal can be generated. Since the distribution mixer 500 does not include a termination resistor for the intermediate frequency signal transmission line, the distribution mixer 500 is the same as the distribution mixers 100 to 400 described above in that the loss of the intermediate frequency signal consumed therein is not caused.

  As described above, according to the distributed mixers 100, 200, 300, 400, and 500 of the present embodiment, the termination resistance of the IF signal transmission line is eliminated, and lumped constant matching is performed instead of distributed matching. The problem that the frequency conversion gain due to the power consumption is reduced can be solved.

  Note that the configuration of the source injection mixer indicated by the distributed mixer 500 can be applied to each of the above embodiments. That is, the configuration excluding the synthesizer 3 of the distributed mixer 100 of the first embodiment may be combined with the configuration shown by the distributed mixer 500 of the present embodiment. Similarly, the configuration of the distribution mixer 300 of the third embodiment excluding the synthesizer 3 may be combined with the configuration of the distribution mixer 500 of the present embodiment. Similarly, the configuration of the distribution mixer 500 of the present embodiment may be combined with the configuration of the distribution mixer 400 of the fourth embodiment.

  Each of the distributed mixers configured as a source injection mixer by combining the configurations of the distributed mixer 500 of the present embodiment has the same effects as the corresponding distributed mixers 100, 200, 300, and 400. As described above, the present invention is not limited to the embodiments described above, and various modifications can be made within the scope of the gist thereof.

1: RF terminal 2: LO terminal 3: Synthesizer 4: Synthetic signal transmission lines 4a to 4P: Synthetic signal transmission line 5: Termination resistors 6a to 6n: Unit mixer 7: IF signal transmission lines 7a to 7n: IF signal transmission line 8: IF terminal 100: distributed mixer

Claims (5)

A synthesizer that synthesizes a high-frequency signal and a local oscillation signal;
A combined signal transmission line for transmitting a combined signal combined by the combiner;
A termination resistor for connecting the termination of the composite signal transmission line to a ground potential;
A unit mixer composed of N (N ≧ 2) common-source FETs that convert the frequency of the synthesized signal of the synthesized signal transmission line into an intermediate frequency signal that is a difference between the high-frequency signal and the local oscillation signal;
An intermediate frequency signal transmission line for transmitting the intermediate frequency signal output from the N unit mixers using one end as an intermediate frequency signal output terminal;
The intermediate frequency signal transmission lines are the N transmission lines having the same electrical length, one end of which is used as the intermediate frequency signal output terminal and the other end of which is connected to the outputs of the N unit mixers.
The impedance of each of the unit mixers viewed from the intermediate frequency signal output terminal is a value obtained by multiplying the impedance of the termination resistor by the N times,
An end of the transmission line connected to the output of the unit mixer is not terminated . The distributed mixer according to claim 1 ,
The distribution mixer according to claim 1, wherein the unit mixer is a cascode unit mixer in which a drain electrode of a common-source FET is connected to a source electrode of a common-gate FET. The distributed mixer according to claim 2 , wherein
When N is the number of stages of the cascode unit mixer,
A delay line is disposed between the drain electrode of the common-source FET and the source electrode of the common-gate FET in each stage so that the intermediate-frequency signal is in phase-matched at the intermediate-frequency signal output terminal. A distribution mixer characterized by that. A high-frequency signal transmission line for transmitting a high-frequency signal;
A termination resistor for connecting the termination of the high-frequency signal transmission line to a ground potential;
A source injection type unit mixer composed of N FETs for outputting an intermediate frequency signal which is a difference between the high frequency signal and the local oscillation signal of the high frequency signal transmission line;
A local oscillation signal distributor for distributing the local oscillation signal to source electrodes of the N unit mixers;
A plurality of intermediate frequency signal transmission lines having the same electrical length respectively connected between drain electrodes of the N unit mixers (N ≧ 2) and intermediate frequency signal output terminals;
The distributed mixer, wherein an end of the intermediate frequency signal transmission line connected to the drain electrode is not terminated. The distributed mixer according to claim 4 , wherein
The intermediate frequency signal transmission lines are the N transmission lines having the same electrical length, one end of which is used as the intermediate frequency signal output terminal and the other end of which is connected to the outputs of the N unit mixers.
Each of the unit mixers seen from the intermediate frequency signal output terminal has a value obtained by multiplying the impedance of the termination resistor by N times.

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