JP6299637B2 - High frequency mixer - Google Patents

Description

  The present invention relates to a high frequency mixer applied to a microwave band or millimeter wave band transceiver.

The high-frequency mixer is an important component that determines the reception sensitivity of the receiver, and in order to increase the reception sensitivity, suppression of image waves caused by noise is required. Hereinafter, the image wave is also referred to as an IM wave.
As a conventional high-frequency mixer capable of suppressing IM waves, there is an image rejection mixer (IRM: Image Rejection Mixer) of Patent Document 1 using a Gilbert cell mixer. The IRM mixes a distribution means for distributing a local oscillator (LO) frequency having an input phase difference and a respective radio frequency (RF) signal having a phase difference with each of the distributed LO frequencies, First and second mixing means for outputting an intermediate frequency (IF) respectively, and phase shifting means for shifting the output IF so as to have a relative phase shift of 90 degrees, respectively. An image rejection mixer including addition means for adding the IF.

Next, the operation of the IRM in Patent Document 1 will be described. This IRM operates as a reception mixer.
A differential RF wave, which is a differential RF signal, and an IM wave caused by noise are input to each Gilbert cell mixer, and the differential LO wave input to the IRM is a differential LO wave having a reference phase. And a differential LO wave having a phase advanced by 90 ° from the wave and input to the Gilbert cell mixer. In each Gilbert cell mixer, a differential RF wave, an IM wave, and a differential LO wave are mixed, and RF-LO and LO-IM are output. Here, RF-LO means the difference frequency between the RF wave and the LO wave, and LO-IM means the difference frequency between the LO wave and the IM wave.

  Here, in a normal mixer, the isolation between the LO and IF terminals is not actually infinite, so that LO waves may leak from the IF terminal. Such leakage of LO waves to the output terminal is called LO leakage. Hereinafter, the numbers in parentheses represent the phase of the signal. In the Gilbert Cell Mixer, one signal (0 °) constituting the differential LO wave is input to the base terminal of a transistor, and the other signal (180 °) is input to the base terminal of another transistor. Since the collector terminals are connected to each other, the LO wave is canceled at the collector terminals, and no LO leak is output.

In the IRM of Patent Document 1, the phase relationship of signals output from each Gilbert cell mixer is shown below.
RF-LO LO-IM
Gilbert Selmixer 1: 0 ° 0 °
Gilbert Selmixer 2: -90 ° 90 °
The signal output from the Gilbert cell mixer 1 is α ° phase-shifted, and the signal output from the Gilbert cell mixer 2 is α ° + 90 ° phase-shifted and the respective signals are combined. A desired IF (= RF-LO) is obtained. The phase relationship before synthesis at this time is as follows.
RF-LO LO-IM
Gilbert Sermixer 1: α ° α °
Gilbert Sermixer 2: α ° α ° + 180 °
Therefore, LO-IM is canceled by synthesis, and RF-LO is output.

JP 2001-284968 A

  In the conventional high-frequency mixer, the IM wave is canceled using the phase relationship between the differential LO waves input to the two Gilbert cells, and the LO leakage is suppressed using the anti-phase relationship between the differential LO waves in the Gilbert cell mixer. It was possible. However, in order to reduce the cost of the wireless device, improve the frequency stability, improve the reception sensitivity, etc., it is required to reduce the frequency of the differential LO wave. In order to lower the frequency of the differential LO wave, it is conceivable to use an even harmonic mixer that performs mixing using the second harmonic of the differential LO wave, instead of the Gilbert cell mixer. In that case, the frequency of the differential LO wave can be halved as compared with the Gilbert cell mixer. However, since the second harmonic of the differential LO wave has an in-phase relationship rather than a reverse phase, there is a problem that LO leakage cannot be suppressed when an even harmonic mixer is used.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a high-frequency mixer that can suppress IM waves and LO leakage even if an even harmonic mixer is used.

  The high-frequency mixer according to the present invention distributes an input IF wave into a first differential IF wave and a second differential IF wave having a phase difference of 90 ° with respect to the first differential IF wave. And the second differential LO wave having a 45 ° phase difference with respect to the first differential LO wave and the first differential LO wave. The first even harmonic mixer for mixing the first differential IF wave and the second harmonic of the second differential LO wave, and the second differential IF wave. And the second even harmonic mixer that mixes the second harmonic of the first differential LO wave and the first 180 that combines the differential signals mixed by the first even harmonic mixer in phase. A synthesizer, a second 180 ° synthesizer that combines the differential signals mixed by the second even harmonic mixer in phase, a signal output from the first 180 ° synthesizer, and a second 1 And 0 signals ° combiner has output and a phase combiner for phase combining.

  According to the high frequency mixer of the present invention, it is possible to cancel the unnecessary image wave 2LO-IF and the LO leak 2LO while outputting the desired output wave 2LO + IF.

1 is a diagram illustrating a configuration example of a high-frequency mixer according to Embodiment 1. FIG. It is a figure which shows the example of 1 structure of an even harmonic mixer. 6 is a diagram illustrating another configuration example of the high-frequency mixer according to Embodiment 1. FIG. 6 is a diagram illustrating a configuration example of a high-frequency mixer according to Embodiment 2. FIG. It is a figure which shows one structural example of the high frequency mixer which concerns on Embodiment 2 at the time of using one LO band in-phase divider | distributor and two LO band 90 degree divider | distributors. It is a figure which shows the structural example of the high frequency mixer which concerns on Embodiment 2 in case IF wave and LO wave are single phase inputs. It is a figure which shows the structural example of the high frequency mixer which concerns on Embodiment 2 in case IF wave and LO wave are single phase inputs.

Embodiment 1
FIG. 1 is a diagram illustrating a configuration example of a high-frequency mixer according to the first embodiment.
The high-frequency mixer includes an even harmonic mixer 1 (an example of a first even harmonic mixer), an even harmonic mixer 2 (an example of a second even harmonic mixer), and an IF band 90 ° distributor 3 (first example). Of 90 ° distributor), LO band 45 ° distributor 4 (example of 45 ° distributor), RF band 180 ° combiner 5 (example of first 180 ° combiner), 6 (second ) And an RF band in-phase synthesizer 7 (an example of an in-phase synthesizer).

  The even harmonic mixer 1 has one differential IF input terminal, two differential LO input terminals, and one RF output terminal, and outputs a mixed wave of the second harmonic of the LO wave and the IF wave. An even harmonic mixer (HMIX: Harmonic MIXer).

FIG. 2 is a diagram illustrating a configuration example of the even harmonic mixer 1.
FIG. 2A is a diagram illustrating a configuration example of the even harmonic mixer 1 when the phase difference between two input differential LO waves is 180 °.
The even harmonic mixer 1 includes a unit mixer 11, a unit mixer 12, and a current source 201.

  The unit mixer 11 includes an inductor 111, a transistor 112 (an example of a first transistor), a transistor 114 (an example of a second transistor), and a transistor 116 (an example of a third transistor). The unit mixer 12 includes an inductor 121, a transistor 122 (an example of a fourth transistor), a transistor 124 (an example of a fifth transistor), and a transistor 126 (an example of a sixth transistor). The unit mixer 11 and the unit mixer 12 have the same configuration, and include an inductor 111 and an inductor 121, a transistor 112 and a transistor 122, a connection point 113 and a connection point 123, a transistor 114 and a transistor 124, a connection point 115 and a connection point 125, and a transistor. 116 and the transistor 126 correspond to each other.

  The transistor 112 and the transistor 114 are connected at their collector terminals (an example of a second terminal) to form a connection point 113, and are connected at an emitter terminal (an example of a third terminal) to form a connection point 115. doing. The base terminals (an example of a first terminal) of the transistors 112 and 114 are LO wave input terminals, and signals having opposite phases are input to each other. In FIG. 2A, signals having opposite phases are input to the LO wave input terminals LO1 and LO2.

  Similarly, the collector terminals of the transistor 122 and the transistor 124 are connected to form a connection point 123, and the emitter terminals are connected to form a connection point 125. The base terminals of the transistor 122 and the transistor 124 are LO wave input terminals, and signals having phases opposite to each other are input. In FIG. 2A, signals having opposite phases are input to the LO wave input terminals LO3 and LO4.

  The collector terminal of the transistor 116 is connected to the connection point 115, and the current source 201 that supplies a constant current to the transistors 112, 114, 116 is connected to the emitter terminal of the transistor 116. The base terminal of the transistor 116 is an IF wave input terminal, which is IF1 in FIG.

  Similarly, the collector terminal of the transistor 126 is connected to the connection point 125, and the current source 201 that supplies a constant current to the transistors 122, 124, and 126 is connected to the emitter terminal of the transistor 126. The base terminal of the transistor 126 is an IF wave input terminal, which is IF2 in FIG. IF waves having opposite phases are input to the base terminal of the transistor 116 and the base terminal of the transistor 126. Since an anti-phase IF wave is input, the transistor 116 and the transistor 126 operate in anti-phase, and a virtual short circuit is formed at the point where the emitter terminals of the transistors 116 and 126 are connected to each other. Thereby, the emitter terminals of the transistor 116 and the transistor 126 are grounded with respect to the high frequency.

  One end of the inductor 111 and the RF wave output terminal 401 are connected to the connection point 113. One end of the inductor 121 and the RF wave output terminal 402 are connected to the connection point 123. The other end of the inductor 111 and the other end of the inductor 121 are connected, and a power source is connected to the connection point. The power supply supplies a DC voltage to the collector terminal of the transistor 112, the collector terminal of the transistor 114, the collector terminal of the transistor 122, and the collector terminal of the transistor 124. In the configuration of the even harmonic mixer 1, since the RF waves output from the output terminal 401 and the output terminal 402 are in a reverse phase relationship, a virtual short circuit is formed at the connection point between the inductor 111 and the inductor 121. . As a result, the even harmonic mixer 1 operates without being affected by the power source impedance. Although the case where a bipolar transistor is used as the transistor has been described here, a field effect transistor or another transistor may be used. When a field effect transistor is used, a base terminal that is a control terminal of the bipolar transistor corresponds to a gate terminal that is a control terminal of the field effect transistor, a collector terminal corresponds to a drain terminal, and an emitter terminal corresponds to a source terminal.

FIG. 2B is a diagram illustrating another configuration example of the even harmonic mixer.
2A, a capacitor 301 (an example of a first capacitor) having one end grounded is loaded at a connection point between the inductor 111 and the inductor 121, and one end is connected to a connection point between the transistor 116 and the transistor 126. The difference is that a grounded capacitor 302 (an example of a second capacitor) is loaded.

  In the even harmonic mixer 1 of FIG. 2B, a capacitor 301 is connected to a connection point on the power source side between the unit mixer 11 and the unit mixer 12, and a connection point on the current source 201 side between the unit mixer 11 and the unit mixer 12. The capacitor 302 is connected to the high frequency to short the high frequency. Therefore, in FIG. 2B, even if the phase difference between the IF wave input to IF1 and the IF wave input to IF2 is shifted from 180 °, the high frequency is short-circuited by the capacitor 301 and the capacitor 302. Therefore, the even harmonic mixer 1 operates without being affected by the load fluctuation caused by the power supply, and can suppress the loss of the RF wave output from the output terminals 401 and 402. This is because a high-frequency current does not flow to the power supply side because a short-circuit point is formed at the connection point between the unit mixer 11 and the unit mixer 12. In addition, the even harmonic mixer 1 of FIG. 2B forms a short-circuit point by the capacitor 301 and the capacitor 302, and therefore can output a signal that is not in reverse phase from the output terminal 401 and the output terminal 402. .

Returning to the description of each component in FIG.
The even harmonic mixer 2 has the same configuration as the even harmonic mixer 1. The unit mixer 21 of the even harmonic mixer 2 corresponds to the unit mixer 11 of the even harmonic mixer 1, and the unit mixer 22 of the even harmonic mixer 2 corresponds to the unit mixer 12 of the even harmonic mixer 1. A differential LO wave having a phase difference with respect to the differential LO wave input to the even harmonic mixer 1 is input to the even harmonic mixer 2, and the differential IF wave input to the even harmonic mixer 1 is converted into a differential IF wave. On the other hand, a differential IF wave having a phase difference is input. The differential LO wave is a differential LO signal composed of two LO waves that are in opposite phase to each other. A differential IF wave is a differential IF signal composed of two IF waves that are in opposite phase to each other.

  The IF band 90 ° distributor 3 divides the input differential IF wave into two signals having a phase difference of 90 °, and the IF terminal of the even harmonic mixer 1 and the IF terminal of the even harmonic mixer 2 Is a 90 ° distributor. In FIG. 1, in the 90 ° distributor 3, 0 ° and 90 ° indicated by broken lines indicate relative phase shift amounts given to signals.

  The LO band 45 ° distributor 4 divides the input differential LO wave into two signals having a phase difference of 45 °, and outputs the LO terminal of the even harmonic mixer 1 and the LO terminal of the even harmonic mixer 2. 45 ° distributor. As the LO band 45 ° distributor 4, for example, a passive circuit having a transmission line whose electrical length is 45 ° different from the output of the Wilkinson in-phase distributor or an 8-phase ring VCO (Voltage Controlled Oscillator) is used.

  The RF band 180 ° synthesizer 5 is a 180 ° synthesizer that combines the differential signals output from the harmonic mixer 1 in phase. That is, the RF band 180 ° synthesizer 5 shifts one of the input signals by 180 ° relative to the other signal, and synthesizes one signal and the other signal. Therefore, when an anti-phase signal is input to the RF band 180 ° combiner, it is combined in phase, but is canceled when an in-phase signal is input. As the RF band 180 ° synthesizer 5, a balanced-unbalanced converter, for example, a balun is used.

  The RF band 180 ° synthesizer 6 is a 180 ° synthesizer that synthesizes the differential signals output from the harmonic mixer 2 in phase.

  The RF band in-phase synthesizer 7 is a synthesizer that performs in-phase synthesis of the signal output from the RF band 180 ° synthesizer 5 and the signal output from the RF band 180 ° synthesizer 6. That is, the RF band in-phase synthesizer 7 synthesizes the input signals without relatively shifting the phase. Therefore, when an in-phase signal is input to the RF band in-phase synthesizer 7, the signals are combined, but when an anti-phase signal is input, they are canceled.

Next, the operation of the high frequency mixer 1 according to Embodiment 1 will be described.
In an IF band 90 ° distributor or the like, the phase between the input signal and the output signal actually changes. For example, even if the phase of the input signal is input at 0 °, the phase of the output signal is not always 0 °. However, in order to simplify the explanation of the phase relationship, the phase reference at each node is 0 °, and the phase difference relationship is maintained.

  As shown in FIG. 1, a differential IF wave composed of a signal having a phase of 0 ° and a signal having a phase of 180 ° is input to the IF band 90 ° distributor 3. The IF band 90 ° distributor 3 distributes the input differential IF wave into a differential IF wave (0 °) serving as a reference and a differential IF wave (90 °) having a 90 ° phase advance, Output. The differential IF wave serving as a reference is input to the even harmonic mixer 1, one signal constituting the differential IF wave is input to the single-phase IF input terminal of the unit mixer 11, and the other signal is input to the unit mixer 12. Input to single-phase IF input terminal. Further, the differential IF wave whose phase is advanced by 90 ° is input to the even harmonic mixer 2, and one signal constituting the differential IF wave is input to the single-phase IF input terminal of the unit mixer 21, and the other signal is input. Is input to the single-phase IF input terminal of the unit mixer 22.

  Differential LO waves are input to the LO band 45 ° distributor 4. The LO band 45 ° distributor 4 distributes the input differential LO wave into a reference differential LO wave and a differential LO wave having a 45 ° phase advance, and outputs the differential LO wave. The reference differential LO wave is distributed in phase and input to the unit mixers 21 and 22 of the even harmonic mixer 2. The differential LO wave having a 45 ° phase advance is distributed in phase and input to the unit mixers 11 and 12 of the even harmonic mixer 1, respectively.

The phase relationship between the LO and IF waves input to the unit mixers 11, 12, 21, and 22 is summarized as follows.
IF LO
Unit mixer 11: 0 ° 45 °, 225 °
Unit mixer 12: 180 ° 45 °, 225 °
Unit mixer 21: 90 ° 0 °, 180 °
Unit mixer 22: -90 ° 0 °, 180 °

  The input IF wave and LO wave are mixed in each unit mixer 11, 12, 21, 22. Since the mixer shown here is an even harmonic mixer, a mixed wave of the second harmonic of the LO wave and the IF wave is output as an RF wave. Therefore, frequencies (2LO + IF, 2LO−IF) that are separated from the frequency of the second harmonic of the LO wave by the frequency of the IF wave are output from the RF terminals of the even harmonic mixers 1 and 2. 2LO + IF is a desired output wave necessary as an output signal of the even harmonic mixer 1. 2LO-IF is an unnecessary image wave. In addition, since the isolation between the LO-RF terminals of the unit mixers 11, 12, 21, and 22 is not actually infinite, the second harmonic (2LO) of the LO wave is generated as the LO leak. , 21 and 22 leak from the RF terminals. Although the fundamental wave of the LO wave also leaks, the frequency is far from the RF wave and can be blocked by a filter or the like, so the leakage of 2LO becomes a problem. 2LO is an unnecessary leakage wave.

The phase relationship at these frequencies is as follows from the phase relationship of the input IF wave and the phase relationship of the LO wave.
2LO + IF 2LO-IF 2LO
Unit mixer 11: 90 ° 90 ° 90 °
Unit mixer 12: -90 ° -90 ° 90 °
Unit mixer 21: 90 ° -90 ° 0 °
Unit mixer 22: -90 ° 90 ° 0 °
In the phase relationship between the output signal of the unit mixer 11 and the output signal of the unit mixer 12, 2LO + IF and 2LO-IF are in an antiphase relationship, whereas 2LO is in an inphase relationship. Similarly, in the phase relationship between the output signal of the unit mixer 21 and the output signal of the unit mixer 22, 2LO + IF and 2LO-IF are in an antiphase relationship, whereas 2LO is in an inphase relationship.

  Therefore, when the output signal of the unit mixer 11 and the output signal of the unit mixer 12 are input to the RF band 180 ° synthesizer 5, the in-phase synthesis is performed for 2LO + IF and 2LO-IF. On the other hand, regarding 2LO, since it is input to the RF band 180 ° synthesizer 5 in the same phase, it is canceled and is not output.

The same applies to the unit mixer 21 and the unit mixer 22, and when the output signal of the unit mixer 21 and the output signal of the unit mixer 22 are input to the RF band 180 ° synthesizer 6, 2LO + IF and 2LO-IF are related. In-phase synthesis. As for 2LO, it is canceled out and is not output. Therefore, the phase relationship of the output signals of the RF band 180 ° combiners 5 and 6 is as follows. “-” Means no output.
2LO + IF 2LO-IF 2LO
180 ° combiner 5: 90 ° 90 ° ―
180 ° combiner 6: 90 ° -90 °-

  Therefore, the output signals from the RF band 180 ° synthesizers 5 and 6 are in-phase synthesized in the RF band in-phase synthesizer 7 and outputted. On the other hand, since the image wave 2LO-IF is a reverse phase synthesis, it is canceled and is not output.

  As described above, according to the first embodiment, it is possible to cancel the unnecessary image wave 2LO-IF and LO leak 2LO while outputting a desired output wave 2LO + IF.

  Here, the input differential LO wave is distributed to two differential LOs with a phase difference of 45 ° by the LO band 45 ° distributor 4 and output to the even harmonic mixers 1 and 2. Although the configuration is shown, an 8-phase ring VCO may be used instead of the LO band 45 ° distributor 4. Hereinafter, a configuration example using an 8-phase ring VCO will be described.

FIG. 3 shows another configuration example of the high-frequency mixer according to the first embodiment.
The ring VCO can output multiple phases according to the number of cascaded stages of the transistors, and an 8-phase output, that is, an output with a 45 ° phase difference is obtained by the 4-stage ring VCO. In a passive circuit using a transmission line, an electrical length corresponding to a phase difference is necessary, and the size increases. Since the ring VCO is configured by cascade connection of transistors, there is an effect of miniaturization. In FIG. 3, the 8-phase ring VCO has a LO wave input terminal, which indicates that synchronization with an external signal is possible. By synchronizing the 8-phase ring VCO to the external signal, the phase stability of the signal output from the 8-phase ring VCO can be improved. However, if the phase stability of the signal output from the 8-phase ring VCO is sufficient, there is no need to input an external signal to the 8-phase ring VCO, and therefore the LO wave input terminal of the 8-phase ring VCO may not be provided. In FIG. 3, the output of the 8-phase ring VCO itself is the LO wave of the high frequency mixer.

  Further, the input of the distributor may be a single phase. FIG. 3 shows a single-phase / orthogonal differential conversion 31 that outputs a differential IF wave as a reference and a differential IF wave with a 90 ° phase advance, with the input of the IF 90 ° distributor as a single phase. By making the input wave a single phase, there is an effect that a phase deviation does not occur in the input wave of the high-frequency mixer, and unnecessary image waves and LO leakage can be easily suppressed. In FIG. 3, a balun is shown as an example of a 180 ° combiner.

Embodiment 2. FIG.
In the first embodiment, the configuration in which the 2LO is canceled using the RF band 180 ° distributors 5 and 6 is shown. However, in the second embodiment, the 2LO is reduced while reducing the RF band 180 ° distributors 5 and 6. A high-frequency mixer having a configuration capable of canceling will be described.

FIG. 4 is a diagram illustrating a configuration example of a high-frequency mixer according to the second embodiment.
4, the same reference numerals as those in FIG. 1 denote the same or corresponding parts, and the description thereof is omitted. The high-frequency mixer of the second embodiment reduces the RF band 180 ° distributors 5 and 6 and replaces the LO band 45 ° distributor 4 with the LO band 90 ° distributor 8 (an example of the second 90 ° distributor). And an RF band 90 ° synthesizer 9 (an example of a 90 ° synthesizer) instead of the RF band in-phase synthesizer 7, and the output terminals of the unit mixers are connected in the even harmonic mixers 1, 2, This is different from the configuration of the first embodiment.

  The LO band 90 ° distributor 8 divides the input differential LO wave into two signals having a phase difference of 90 °, and outputs the LO terminal of the even harmonic mixer 1 and the LO terminal of the even harmonic mixer 2. Is a 90 ° distributor. For example, a polyphase filter or the like is used as the LO band 90 ° distributor 4.

  The RF band 90 ° synthesizer 9 is a 90 ° synthesizer that synthesizes signals having a 90 ° phase difference output from the even harmonic mixers 1 and 2 in the same phase. That is, the RF band 90 ° synthesizer 9 shifts one input signal by 90 ° relative to the other signal, and synthesizes one signal and the other signal in phase.

Next, the operation of the high frequency mixer according to Embodiment 2 will be described.
As shown in FIG. 4, the differential IF wave is input to the IF band 90 ° distributor 3. The IF band 90 ° distributor 3 distributes and outputs the input differential IF wave into a differential IF wave serving as a reference and a differential IF wave having a 90 ° phase advance. A differential IF wave serving as a reference is input to the even harmonic mixer 1, one signal constituting the differential IF wave is input to the IF input terminal of the unit mixer 11, and the other signal is input to the IF of the unit mixer 12. Input to the input terminal. Further, the differential signal whose phase is advanced by 90 ° is input to the even harmonic mixer 2, one signal constituting the differential signal is input to the IF input terminal of the unit mixer 21, and the other signal is the unit mixer 22. To the IF input terminal.

  Differential LO waves are input to the LO band 90 ° distributor 8. The LO band 90 ° distributor 8 distributes and outputs the input differential LO wave into a differential LO wave having a reference phase and a differential LO wave having a 90 ° phase advance. Differential LO waves having a reference phase are distributed in phase and input to the unit mixer 11 of the even harmonic mixer 1 and the unit mixer 21 of the even harmonic mixer 2 respectively. The differential LO wave whose phase is advanced by 90 ° is distributed in phase and is input to the unit mixer 12 of the even harmonic mixer 1 and the unit mixer 22 of the even harmonic mixer 2 respectively.

The phase relationship between the LO and IF waves input to the unit mixers 11, 12, 21, and 22 is summarized as follows.
IF LO
Unit mixer 11: 0 ° 0 °, 180 °
Unit mixer 12: 180 ° 90 °, -90 °
Unit mixer 21: 90 ° 0 °, 180 °
Unit mixer 22: -90 ° 90 °, -90 °

  The input IF wave and LO wave are mixed in each unit mixer 11, 12, 21, 22. Since the mixer shown here is an even harmonic mixer, a mixed wave of the second harmonic of the LO wave and the IF wave is output as an RF wave. Therefore, the frequencies (2LO + IF, 2LO−IF) that are separated from the frequency of the LO wave second harmonic by the IF wave frequency are output from the RF terminals of the even harmonic mixers 1 and 2. In addition, since the isolation between the LO-RF terminals of the unit mixers 11, 12, 21, and 22 is not actually infinite, the second harmonic (2LO) of the LO wave is generated as the LO leak. , 21 and 22 leak from the RF terminals.

The phase relationship at these frequencies is as follows from the phase relationship of the input IF wave and the phase relationship of the LO wave.
2LO + IF 2LO-IF 2LO
Unit mixer 11: 0 ° 0 ° 0 °
Unit mixer 12: 0 ° 0 ° 180 °
Unit mixer 21: 90 ° -90 ° 0 °
Unit mixer 22: 90 ° -90 ° 180 °

  In the even harmonic mixer 1, since the output terminal of the unit mixer 11 and the output terminal of the unit mixer 12 are connected, the output signal of the unit mixer 11 and the unit mixer 12 signal are directly synthesized. Therefore, in the phase relationship between the output signal of the unit mixer 11 and the output signal of the unit mixer 12, 2LO + IF and 2LO-IF are in phase, whereas 2LO is in reverse phase. Therefore, 2LO cancels out and 2LO + IF and 2LO-IF are combined in phase. For this reason, the even harmonic mixer 1 outputs 2LO + IF and 2LO-IF.

Similarly to the even harmonic mixer 1, in the even harmonic mixer 2, the output terminal of the unit mixer 21 and the output terminal of the unit mixer 22 are connected, so that the output signal of the unit mixer 21 and the output signal of the unit mixer 22 are connected. Is synthesized directly. Therefore, 2LO cancels out and 2LO + IF and 2LO-IF are combined in phase. For this reason, the even harmonic mixer 2 outputs 2LO + IF and 2LO-IF. Therefore, the phase relationship of the input signals of the RF band 90 ° synthesizer 9 is as follows.
2LO + IF 2LO-IF 2LO
Even harmonic mixer 1: 0 ° 0 ° ―
Even harmonic mixer 2: 90 ° -90 °-

 Therefore, in the RF band 90 ° synthesizer 9, 2LO + IF is in-phase synthesized and output. On the other hand, since 2LO-IF is a reverse phase synthesis, it is canceled and not output.

  As described above, according to the second embodiment, it is possible to cancel the unnecessary 2LO-IF and 2LO while outputting desired 2LO + IF. In addition, in the second embodiment, the RF band 180 ° combiners 5 and 6 that are necessary in the first embodiment can be deleted.

  In the above description, the LO band 90 ° distributor 8 distributes the input differential LO wave into a differential LO wave having a reference phase and a differential LO wave having a 90 ° phase difference. Although the configuration example in which dynamic LO waves are distributed in-phase and input to the even harmonic mixers 1 and 2 has been shown, other configurations may be used as long as the phase relationship input to the even harmonic mixers 1 and 2 is the same as described above. . Hereinafter, another configuration example will be described.

  FIG. 5 is a diagram illustrating a configuration example of the high-frequency mixer according to the second embodiment when one LO band in-phase distributor and two LO band 90 ° distributors are used. After the input differential LO wave is distributed in-phase by the LO band in-phase distributor 10, 90 ° phase difference distribution is performed by the LO band 90 ° distributor 100 on one of the distributed differential LO waves to obtain a reference phase. And a LO wave having a 90 ° phase difference are input to the even harmonic mixer 1. Further, 90 ° phase difference distribution is performed by the LO band 90 ° distributor 101 with respect to the other differential LO wave distributed by the LO band in-phase distributor 10, and the differential LO wave having the reference phase is about 90 °. An LO wave having a phase difference is input to the even harmonic mixer 2.

  Even in such a configuration, the phase relationship between the differential LO wave input to the even harmonic mixer 1 and the differential LO wave input to the even harmonic mixer 2 is the same as in FIG. Therefore, the same effect as the configuration shown in FIG. Further, in the case of FIG. 4, the LO wave of the four-phase signal is wired by four signal lines, whereas in the case of FIG. 5, the LO wave of the two-phase signal is wired by two signal lines. Therefore, the phase deviation between the two signals can be reduced, and there is an effect of preventing the suppression amount of the image wave and the LO leak from being deteriorated due to the phase deviation. This is because the wiring length of the signal lines is less likely to be different when wiring with the two signal lines than when wiring with the four signal lines.

FIG. 6 is a diagram illustrating a configuration example of the high-frequency mixer according to the second embodiment when the IF wave and the LO wave are single-phase inputs.
The high-frequency mixer shown in FIG. 6 distributes an input single-phase IF wave to two differential IF waves having a phase difference of 90 ° by using an IF band single-phase to quadrature converter 31, and one of them is even. The signal is input to the harmonic mixer 1 and the other is input to the even harmonic mixer 2. The high-frequency mixer shown in FIG. 6 distributes one input single-phase LO wave to two differential LO waves having a phase difference of 90 ° using the LO band single-phase to quadrature differential converter 81. In addition, the two differential LO waves are respectively distributed in phase and input to the even harmonic mixer 1 and the even harmonic mixer 2.

  Even in such a configuration, the phase relationship between the differential LO wave input to the even harmonic mixer 1 and the differential LO wave input to the even harmonic mixer 2 is the same as in FIG. Therefore, the same effect as the configuration shown in FIG. Furthermore, in the case of FIG. 4, since the input to the distributor is differential, since FIG. 6 is a single phase, there is no phase deviation of the input wave (IF wave, LO wave) to the high frequency mixer, There is an effect of increasing suppression of image waves and LO leakage.

FIG. 7 is a diagram illustrating a configuration example of a high-frequency mixer according to the second embodiment when the IF wave and the LO wave are single-phase inputs.
In FIG. 7, an input single-phase IF wave is distributed to two differential IF waves having a phase difference of 90 ° using an IF band single-phase to quadrature converter 31, and one of them is an even harmonic mixer. 6 is the same as FIG. 6 in that the other is input to the even harmonic mixer 2.

  The high-frequency mixer of FIG. 7 first distributes one input single-phase LO wave into two in-phase single-phase LO waves using the LO band in-phase distributor 20. Next, one single-phase LO wave is distributed to two differential LO waves having a phase difference of 90 ° by using the single-phase to quadrature converter 200 and input to the even harmonic mixer 1. Similarly, the other single-phase LO wave is distributed to two differential LO waves having a phase difference of 90 ° using the single-phase-orthogonal converter 201 and input to the even harmonic mixer 2.

  Even in such a configuration, the phase relationship between the differential LO wave input to the even harmonic mixer 1 and the differential LO wave input to the even harmonic mixer 2 is the same as in FIG. Therefore, the same effect as the configuration shown in FIG. Further, since the input wave (IF wave, LO wave) to the high frequency mixer is a single phase as in the case of FIG. 6, there is no phase deviation, and the signal line for the LO wave is changed from two phases to a single phase as compared with the case of FIG. Therefore, it is possible to reduce the phase deviation due to the difference in the wiring length of the signal lines, and to increase the suppression of the image wave and the LO leak.

1 2 Even harmonic mixer, 3 IF band 90 ° distributor, 4 LO band 45 ° distributor, 5 6 RF band 180 ° combiner, 7 RF band in-phase combiner, 11 12 21 22 unit mixer, 8 LO band 90 ° Distributor, 9 RF band 90 ° combiner, 10 LO band in-phase distributor, 100 101 LO band 90 ° distributor, 31 IF band single-phase to quadrature differential converter, 41 LO band 8-phase ring VCO, 51 61 Balun, 81 LO band single-phase to quadrature differential converter, 20 LO band in-phase distributor, 200 201 LO band single-phase to quadrature differential converter, 111 112 114 116 121 122 124 126 126 transistor, 111 121 inductor, 113 115 123 126 connection point, 201 current source, 301 302 capacitor, 401 402 output terminal.

Claims (9)

A first 90 ° distributing the input IF wave to a first differential IF wave and a second differential IF wave having a phase difference of 90 ° with respect to the first differential IF wave. A distributor;
A 45 ° distributor for distributing the input LO wave into a first differential LO wave and a second differential LO wave having a phase difference of 45 ° with respect to the first differential LO wave; ,
A first even harmonic mixer that mixes the first differential IF wave and a second harmonic of the second differential LO wave;
A second even harmonic mixer that mixes the second differential IF wave and a second harmonic of the first differential LO wave;
A first 180 ° synthesizer that synthesizes the differential signal mixed by the first even harmonic mixer in phase;
A second 180 ° combiner that combines the differential signals mixed by the second even harmonic mixer in phase with each other;
A high-frequency mixer comprising: an in-phase synthesizer that in-phase synthesizes a signal output from the first 180 ° synthesizer and a signal output from the second 180 ° synthesizer. A first 90 ° distributing the input IF wave to a first differential IF wave and a second differential IF wave having a phase difference of 90 ° with respect to the first differential IF wave. A distributor;
A second 90 ° that distributes the input LO wave into a first differential LO wave and a second differential LO wave having a phase difference of 90 ° with respect to the first differential LO wave. A distributor;
One signal composing the first differential IF wave and a second harmonic of the first differential LO wave are mixed, and the other signal composing the first differential IF wave and the first signal A first even harmonic mixer that mixes the second harmonic of the two differential LO waves;
One signal composing the second differential IF wave and a second harmonic of the first differential LO wave are mixed, and the other signal composing the second differential IF wave and the first signal A second even harmonic mixer that mixes the second harmonic of the two differential LO waves;
A high-frequency mixer provided with a 90 ° synthesizer that phase-shifts one of the signal output from the first even harmonic mixer or the signal output from the second even harmonic mixer by 90 ° and synthesizes the same with the other. .   The high-frequency mixer according to claim 1, wherein the LO wave input to the 45 ° distributor is a single phase.   The high-frequency mixer according to claim 1 or 2, wherein the IF wave input to the first 90 ° distributor is a single phase.   The high-frequency mixer according to claim 2, wherein the LO wave input to the second 90 ° distributor is a single phase.   The high-frequency mixer according to claim 1, wherein the first 90 ° distributor is configured using a transmission line.   The high-frequency mixer according to claim 2, wherein the second 90 ° distributor is configured using an oscillator. The first even harmonic mixer and the second even harmonic mixer include first to sixth transistors each having a first terminal, a second terminal, and a third terminal which are control terminals. Each with a current source,
In the first transistor, one signal constituting the first differential LO wave is input to the first terminal,
In the second transistor, the other signal constituting the first differential LO wave is input to the first terminal, and the second terminal of the first transistor is connected to the second terminal. The third terminal of the first transistor is connected to the third terminal;
In the third transistor, one signal constituting the differential IF wave is input to the first terminal, the third terminal of the second transistor is connected to the second terminal,
In the fourth transistor, one of the signals constituting the second differential LO wave is input to the first terminal,
In the fifth transistor, the other signal constituting the second differential LO wave is input to the first terminal, and the second terminal of the fourth transistor is connected to the second terminal. The third terminal of the fourth transistor is connected to the third terminal;
In the sixth transistor, the other signal constituting the differential IF wave is input to the first terminal, the third terminal of the fifth transistor is connected to the second terminal,
One end of the current source is connected to the third terminal of the third transistor and the third terminal of the sixth transistor, and the other end is grounded.
A voltage is supplied to the second terminal of the first transistor and the second terminal of the fourth transistor, and the second terminal of the first transistor and the second terminal of the fourth transistor. The high-frequency mixer according to claim 1, wherein an RF wave is output from the terminal. The first even harmonic mixer and the second even harmonic mixer include first to sixth transistors each having a first terminal, a second terminal, and a third terminal which are control terminals. Each comprising a current source and first and second capacitors;
In the first transistor, one signal constituting the first differential LO wave is input to the first terminal,
In the second transistor, the other signal constituting the first differential LO wave is input to the first terminal, and the second terminal of the first transistor is connected to the second terminal. The third terminal of the first transistor is connected to the third terminal;
In the third transistor, one signal constituting the differential IF wave is input to the first terminal, the third terminal of the second transistor is connected to the second terminal,
In the fourth transistor, one of the signals constituting the second differential LO wave is input to the first terminal,
In the fifth transistor, the other signal constituting the second differential LO wave is input to the first terminal, and the second terminal of the fourth transistor is connected to the second terminal. The third terminal of the fourth transistor is connected to the third terminal;
In the sixth transistor, the other signal constituting the differential IF wave is input to the first terminal, the third terminal of the fifth transistor is connected to the second terminal,
One end of the current source is connected to the third terminal of the third transistor and the third terminal of the sixth transistor, and the other end is grounded.
One end of the first capacitor is connected to a connection point between the second terminal of the first transistor and the second terminal of the fourth transistor, and the other end is grounded.
One end of the second capacitor is connected to a connection point between the third terminal of the third transistor and the third terminal of the sixth transistor, and the other end is grounded.
A voltage is supplied to the second terminal of the first transistor and the second terminal of the fourth transistor, and the second terminal of the first transistor and the second terminal of the fourth transistor. The high frequency mixer according to claim 2, wherein an RF wave is output from the terminal.

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