JPH08242123A - Mixer - Google Patents

Abstract

(57) [Abstract] [Object] The present invention is used in a transmitter / receiver of a wireless communication system, and an object thereof is to miniaturize an even harmonic mixer that mixes a second harmonic of a local oscillation wave and a signal wave. [Configuration] A diode pair 31 in which two diodes are connected in parallel with opposite polarities and a lumped constant, and a short-circuit state occurs at the frequency of the local oscillation wave and an open state occurs at the frequency of the signal wave. Demultiplexing circuit 64 of
The second demultiplexing circuit 68 is configured by a lumped constant and is open at the frequency of the local oscillation wave and is short-circuited at the frequency of the signal wave. [Effect] Since the demultiplexing circuit is configured by using lumped constants instead of stubs, the size does not increase at low frequencies.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mixer for use in a transmitter / receiver of a wireless communication system and outputting a mixed wave of a second harmonic of a local oscillation wave and a signal wave.

[0002]

2. Description of the Related Art A mixer that outputs a mixed wave of a second harmonic of a local oscillation wave and a signal wave is called an even harmonic mixer. By mixing the second harmonic of the local oscillation wave and the signal wave, the even harmonic mixer produces even harmonics of the local oscillation wave, and
Odd-order harmonics of the conductance between the terminals of the diode can be suppressed.

Various configurations of even harmonic mixers have been reported for some time. Figure 8 shows the IEEE-sponsored International Microwave Symposium held in Boston in June 1991.
It is an even harmonic mixer described on pages 879 to 882 of 1991 MTT-S Digest. In the figure, reference numeral 31 is an anti-parallel diode pair (APDP), which is configured by connecting mixer diodes 30a and 30b having opposite polarities in parallel.

Reference numeral 32 is an RF terminal to which a high frequency signal of frequency f _rf is input, 33 is an LO terminal to which a local oscillation wave of frequency f _p is input, and 34 is a baseband signal (or intermediate frequency signal) which is a mixed output. This is the output baseband terminal. The RF terminal 32 is a capacitor 3 for DC cut.
8 is connected to one end (A end) of APDP. The baseband terminal 34 is an inductor 3 that is an RF choke.
The same AP as the terminal to which the RF terminal 32 is connected via
It is connected to one end (A end) of DP31. Further, the LO terminal 33 is connected to the other end (B end) of the APDP 31 different from the terminal to which the RF terminal 32 and the baseband terminal 33 are connected.

Reference numeral 35 is a tip open stub connected to the A end of the APDP 31, and 36 is a tip shorting stub connected to the B end of the APDP 31. The even harmonic mixer of FIG. 8 has a configuration in which the open tip stub 35 and the short tip stub 36 are used to split f _p and f _rf (= 2f _p ).

FIG. 9 is an example of a configuration diagram of a receiver having a homodyne configuration to which the even harmonic mixer of FIG. 8 is applied.
In FIG. 9, 1 is an antenna (ANT), 2 is a low noise amplifier (LNA) that amplifies the signal wave from the antenna 1, 3
Is a band pass filter (BPF) that passes the signal wave contained in the output of the low noise amplifier 2, 41 is the signal wave detected based on the local oscillation wave, and the modulated signal components of the signal wave are output as I signal and Q signal. It is an even harmonic quadrature mixer.

The even harmonic quadrature mixer 41 has a 0-degree distributor 6 for dividing the output of the band-pass filter 3 into two with equal phase and equal amplitude, and has a phase difference of 45 degrees upon receiving a local oscillation wave from the outside. , A 45 degree phase shifter 4 for distributing two signals of equal amplitude
2. Even harmonic mixer 40 that mixes the distributed signal wave and the local signal and outputs the I signal and the Q signal, respectively
a, 40b. Even harmonic mixer 40a, 4
0b is the one shown in FIG. Here, when the frequency of the signal wave is f _rf and the frequency of the local oscillation wave is f _p , f _rf
= 2f _p . Further, the phase shifter 42 performs the phase shift of 45 degrees because the even harmonic mixer mixes the double wave of the local oscillation wave and the signal wave, and thus the phase difference of 45 degrees is doubled to 90 degrees. This is because the phase difference is in degrees.

Reference numeral 8 is a local oscillator for generating a local oscillation wave, and 9
a and 9b are low-pass filters (LPFs) for filtering the I output and Q output of the even harmonic quadrature mixer 41, respectively.
a and 10b are base band amplifiers (AM) for amplifying the outputs of the low pass filters (LPF) 9a and 9b, respectively.
P) and 11 are demodulation circuits that demodulate data based on the outputs of the baseband amplifiers 10a and 10b.

Next, the operation will be described. The reception signal received by the antenna 1 is input to the even harmonic quadrature mixer 41 via the low noise amplifier 2 and the bandpass filter 3.
In the even harmonic quadrature mixer 41, the even harmonic mixer 40
a mixes the received signal with the second harmonic of the local oscillation wave to obtain a baseband I signal. The even harmonic mixer 40b mixes the received signal with the 90% phase-shifted local oscillator wave to obtain a baseband Q signal. The I signal and the Q signal are low-pass filters 9a and 9b and a baseband amplifier 10.
It is input to the demodulation circuit 11 via a and 10b. The data is demodulated in the demodulation circuit 11.

Next, the operation of the even harmonic mixers 40a and 40b will be described with reference to FIGS. 8, 10 and 11. In the even harmonic mixers 40a and 40b, the tip open stub 35
And the tip shorting stub 36 is approximately a quarter of f _p.
It is designed to be a wavelength, that is, about half wavelength for f _rf . At this time, the impedances of the tip open stub 35 and the tip short-circuit stub 36 viewed from the APDP 31 are as shown in FIGS. 10 and 11, respectively.

The tip open stub 35 is connected to the terminals of the APDP 31 on the RF terminal 32 and the baseband terminal 34 side, and as shown in FIG. 10, near DC and f _rf (= 2f _p ).
High impedance in the vicinity. Therefore, A
The PDP 31 is connected to each terminal. On the other hand, f _p
The impedance becomes low in the vicinity, and the APDP 31 is grounded.

On the contrary, the tip short-circuit stub 36 is connected to the LO terminal 3
11 is connected to a terminal on the side of the APDP 31 on the side of FIG.
As described above, the impedance becomes low in the vicinity of DC and in the vicinity of f _rf , and the APDP 31 is grounded. On the other hand, the impedance becomes high in the vicinity of f _p , and the APDP 31 is connected to the LO terminal 33.

When the local oscillation wave is supplied to the LO terminals of the even harmonic mixers 40a and 40b, the mixer diodes 30a and 30b are turned on every half cycle and a current flows. As a result, the APDP 31 operates so that the conductance increases every half cycle. Therefore, there are only odd harmonics of the local oscillation wave and even harmonics of the conductance.

Therefore, when the mixer is constructed by applying this APDP31, since it seems that the APDP31 is modulated by the even harmonics of the local oscillation wave, the second harmonic wave 2f _p of the local oscillation wave and the signal wave are generated. mixing is carried out in the f _rf, mixing of the f _p and f _rf is suppressed.

According to this even harmonic mixer, the even harmonics of the local oscillation wave and the odd harmonics of the conductance can be suppressed only by balancing the two diodes. High suppression is possible.

FIG. 12 shows another example of a conventional even harmonic mixer, which is the C-ANN Autumn Meeting of the Institute of Electronics, Information and Communication Engineers, 1993.
Reported in 47. In the figure, 80 is a slot line whose one end is the LO terminal 33, 81 is a coplanar line to which the RF terminal 32 is connected to one end via the capacitor 38 and the baseband terminal 34 is connected via the inductor 37, Reference numerals 82a and 82b are wires for suppressing a balanced mode excited in the coplanar line 81. In addition, the other end of the slot line 80, the coplanar line 8
The other end of 1 is connected to an APDP 31 configured by connecting anti-diode pairs 31a to 31d in a ring shape.

The operation of the even harmonic mixer of FIG. 12 is similar to the operation of the even harmonic mixer of FIG. However, according to the even harmonic mixer of FIG. 12, since the slot line 80 and the coplanar line 81 can be isolated from each other,
There is an advantage that demultiplexing is possible in a wide band.

FIG. 13 shows another example of the conventional mixer, which is published by Sofukan, and is co-authored by PR Gray and RG Meyer, "Analog Integrated Circuit Design Technology" (PRGray, RGM).
ayer: ”Analysis and Design of analog integrated ci
A balanced mixer for a Gilbert cell using transistors, described in Section 10.3 of rcuits ”).

In FIG. 13, 18a and 18b are resistors,
Reference numerals 19a to 19f are transistors, and 20 is a current source.
RF and LO are differential inputs. Signals LO having opposite phases are supplied to the transistors 19a and 19b and the transistors 19c and 19d. Also, signals RF having opposite phases are supplied to the transistors 19e and 19f. The mixed wave generated by the analog multiplication of RF and LO performed by the transistors 19a to 19f is generated by the transistor 1
Collectors of 9b and 19d, transistors 19a and 1
It is output to the baseband output terminal 17 which is a differential output and is connected to the collectors of 9c. Note that RF and LO are canceled and are not output to the baseband output terminal 17.

[0020]

By the way, the conventional even harmonic mixer shown in FIGS. 8 and 12 has a problem that the size is large.

Although the configuration of the even harmonic mixer shown in FIG. 8 is simple, if it is attempted to realize it in a relatively low frequency region, the open tip stub 35 and the short circuit stub 36 will become long, and inevitably. It becomes large.

If the even harmonic mixer shown in FIG. 12 is integrated and miniaturized, it is difficult to integrate the slot line 80 considering the connection with the ground conductor, and the slot line 80 is integrated with an external microstrip line. There is a problem that the connection becomes a narrow band.

Although the Gilbert cell using the transistor of FIG. 13 can be integrated and miniaturized, if it cannot be applied to the even harmonic mixer as it is or the characteristics of the transistor are not uniform, each transistor can be There is a problem that the rectified current of the local oscillation wave is not cancelled, and DC offset occurs in addition to the I signal and the Q signal.

An object of the present invention is to provide an even harmonic mixer which can be miniaturized without degrading its performance.

[0025]

According to a first aspect of the present invention, there is provided a mixer having two diodes connected in parallel with opposite polarities, the first parallel connection ends of the two diodes being a signal wave input end and a mixing end. It is composed of a lumped constant and a diode pair having a second parallel connection end as a wave output end and a local oscillation wave input end, and becomes short-circuited at the frequency of the local oscillation wave, and at the frequency of the signal wave. It will be in the open state,
A first branching circuit connected to the first parallel connection terminal;
A second demultiplexing circuit which is formed of a lumped constant, is open at the frequency of the local oscillation wave, is short-circuited at the frequency of the signal wave, and is connected to the second parallel connection end. It is a thing.

In a mixer according to a second aspect of the present invention, the first demultiplexing circuit is composed of a series resonance circuit including a capacitor and an inductor connected in series with each other, and a capacitor connected in parallel with the series resonance circuit. It is a thing.

In the mixer according to a third aspect of the present invention, the first branching circuit is composed of a parallel resonance circuit including a capacitor and an inductor connected in parallel with each other, and a capacitor connected in series with the parallel resonance circuit. It is a thing.

In the mixer according to a fourth aspect, the second branching circuit is composed of a series resonance circuit including a capacitor and an inductor connected in series with each other, and an inductor connected in parallel with the series resonance circuit. It is a thing.

In the mixer according to a fifth aspect, the second branching circuit is composed of a parallel resonance circuit including a capacitor and an inductor connected in parallel to each other, and an inductor connected in series to the parallel resonance circuit. It is a thing.

According to a sixth aspect of the present invention, a mixer amplifies a local oscillation wave and outputs it as a first output and a second output having opposite phases to each other, and two diodes connected in parallel with opposite polarities. And a diode ring formed by connecting a plurality of respective diode pairs in a ring shape. Based on the two outputs of the differential amplifier, the second harmonic of the local oscillation wave and the diode ring are input. And a mixing section for outputting a mixed wave with the signal wave.

A mixer according to a seventh aspect of the invention further comprises a filter for removing harmonics contained in the output of the differential amplifier and supplying the harmonics to the mixing section.

A mixer according to claim 8 amplifies a signal wave and outputs a first differential amplifier that outputs a first output and a second output which are in opposite phases to each other, and a local oscillation wave that receives the local oscillation wave. A second differential amplifier that generates a second harmonic of the oscillating wave, multiplies the second harmonic by the first output of the first differential amplifier, and outputs a differential signal; Second harmonic wave having an output terminal connected in parallel with the output terminal of the differential amplifier, and receiving the local oscillation wave and having a phase opposite to the second harmonic of the local oscillation wave generated in the first differential amplifier. And a third differential amplifier that multiplies the second harmonic by the second output of the first differential amplifier and outputs as a differential signal.

[0033]

According to the invention of claim 1, a diode pair formed by connecting two diodes in parallel with opposite polarities to each other is input to the signal wave input to the first parallel connection end and the second parallel connection end. By mixing with the second harmonic of the local oscillation wave, the first
Output to the parallel connection end of the
Second demultiplexing circuit constituted by a lumped constant, wherein the demultiplexing circuit makes the first parallel connection end short-circuited at the frequency of the local oscillation wave and is open at the frequency of the signal wave. However, the second parallel connection terminal is opened at the frequency of the local oscillation wave and short-circuited at the frequency of the signal wave.

In the second aspect of the invention, the series resonance circuit including the capacitor and the inductor connected in series with each other and the capacitor connected in parallel to the series resonance circuit form the first branching circuit.

In the third aspect of the invention, the parallel resonance circuit including the capacitor and the inductor connected in parallel to each other and the capacitor connected in series to the parallel resonance circuit form the first branching circuit.

In the fourth aspect of the invention, the series resonance circuit including the capacitor and the inductor connected in series to each other and the inductor connected in parallel to the series resonance circuit form the second branching circuit.

In the fifth aspect of the invention, the parallel resonance circuit including the capacitor and the inductor connected in parallel to each other and the inductor connected in series to the parallel resonance circuit constitute the second branching circuit.

In the sixth aspect of the present invention, the differential amplifier amplifies the local oscillation wave and outputs it as the first output and the second output which are in opposite phase to each other, and two diodes are connected in parallel with opposite polarities. The diode ring composed by connecting a plurality of diode pairs each in a ring shape,
Based on the two outputs of the differential amplifier, a mixed wave of the second harmonic of the local oscillation wave and the signal wave input to the diode ring is output.

In the invention of claim 7, the filter removes harmonics contained in the output of the differential amplifier and supplies the harmonics to the mixing section.

In the eighth aspect of the present invention, the first differential amplifier amplifies the signal wave and outputs it as a first output and a second output which are in opposite phase to each other, and the second differential amplifier is The local oscillator wave is received to generate a second harmonic of the local oscillator wave, and the second harmonic is multiplied by the first output of the first differential amplifier to output as a differential signal, and the third signal is output. Differential amplifier has an output end connected in parallel with the output end of the second differential amplifier, and receives the local oscillation wave and receives twice the local oscillation wave generated by the first differential amplifier. A second harmonic having a phase opposite to that of the wave is generated, and the second harmonic is multiplied by the second output of the first differential amplifier to output as a differential signal.

[0041]

【Example】

Example 1. The even harmonic mixer of the first embodiment can be miniaturized by using a lumped-constant demultiplexing circuit that realizes the same function, instead of the stub.

FIG. 1 is a circuit diagram of the even harmonic mixer of the first embodiment. In the figure, 31 is an anti-parallel diode pair (APDP) formed by connecting mixer diodes 30a and 30b of opposite polarities in parallel. Hereinafter, for convenience of description, two connection ends of the APDP 31 will be respectively referred to as
Set to A end and B end.

Reference numeral 32 is an RF terminal which is connected to the A terminal of the APDP 31 via a capacitor 38 for blocking direct current and receives a high frequency reception signal of frequency f _rf , and 33 is the APDP 3
The LO terminal connected to the B terminal of 1 to which the local oscillation signal of the frequency f _p is input, 34 is connected to the A terminal of the APDP 31 via the inductor 37 for blocking the high frequency signal, and detects the detected baseband signal. This is the baseband terminal for output.

Reference numeral 64 is a lumped constant stub A connected to the A terminal of the APDP 31. The lumped constant stub A64 is
It is composed of capacitors 61 and 62 and an inductor 63.
In the lumped constant stub A64, the capacitor 61 having the capacitance Cp2p has one end connected to the A end and the other end connected to the ground end. A capacitor 62 having a capacitance Csp and an inductor 63 having an inductance Lsp are connected in series.
A series circuit including the capacitor 62 and the inductor 63 is connected to the capacitor 61 in parallel.

68 is a lumped constant stub B connected to the B end of the APDP 31. Lumped constant stub B6
5 includes a capacitor 66 and inductors 65 and 67. In the lumped constant stub B64, the inductor 65 having the inductance Lpp and the capacitor 66 having the capacitance Cpp are connected in parallel. One of the two parallel connection ends is connected to the B end of the APDP 31. One end of the inductor 67 having the inductance Ls2p is grounded.
The parallel circuit including the inductor 65 and the capacitor 66 and the inductor 67 are connected in series.

Next, the operation will be described. The lumped constant stub A64 is designed to operate similarly to the open-end stub 35 of FIG. That is, at f _p
The capacitor 62 and the inductor 63 resonate in series to have a low impedance, and the series resonance circuit including the capacitor 62 and the inductor 63 and the capacitor 61 resonate in parallel at f _rf to have a high impedance. Designed to be. Also, the lumped constant stub A6
Since 4 is open in direct current (DC), it has high impedance. Therefore, the lumped constant stub A64 is
It has the same characteristics as in FIG.

The lumped stub B68 is designed to operate similarly to the tip shorting stub 36 of FIG. That is, at f _p , inductor 65 and capacitor 66
_Are designed to resonate in parallel to have a high impedance, and at f _rf , the parallel resonance circuit including the inductor 65 and the capacitor 66 and the inductor 67 resonate in series to have a low impedance. . Also,
The lumped constant stub B68 has a low impedance because it is a short circuit at DC. Therefore, the lumped constant stub B68 has the same characteristics as those in FIG.

The lumped constant stubs A64 and B68 are equivalent to the open tip stub 35 and the short tip stub 36 in FIG. Therefore, the even harmonic mixer of FIG. 1 operates similarly to that of FIG.

As described above, according to the configuration of the first embodiment, the branching circuit can be formed by the lumped constant while having the same impedance characteristic as the conventional stub.
Therefore, the even harmonic mixer can be configured without using a stub that becomes large when the frequency is low, and the mixer can be downsized.

Example 2. FIG. 2 is a circuit diagram of the even harmonic mixer of the second embodiment. In the figure, 70 is an APD
It is a lumped constant stub C connected to the A end of P31.
The lumped constant stub C70 includes capacitors 61 and 62 and an inductor 69. In the lumped constant stub C70, the capacitor 61 having the capacitance Cp2p and the inductance Lp
The 2p inductor 69 is connected in parallel. One end of the parallel circuit including the capacitor 61 and the inductor 69 is connected to the A end of the APDP 31. The parallel circuit and the capacitor 62 having the capacitance Csp are connected in series. The parallel circuit is grounded via the capacitor 62.

A lumped constant stub D 72 is connected to the B end of the APDP 31. Lumped constant stub D7
2 includes a capacitor 71 and inductors 65 and 67. In the lumped constant stub D72, the inductor 67 having the inductance Ls2p and the capacitor 71 having the capacitance Cs2p are connected in series to form a series circuit. This series circuit has one end connected to the B end of the APDP 31 and the other end grounded. Then, the inductor 67 and the capacitor 71
The series circuit composed of and the inductor 65 are connected in parallel.

Reverse polarity mixer diodes 30a, 30b
Anti-parallel diode pair (APDP) 31, RF terminal 32, LO terminal 33, baseband terminal 34, inductor 37, capacitor 38
Is the same as that shown in FIG.

Next, the operation will be described. The lumped-constant stub C70 is designed to have a characteristic equivalent to that of the open-end stub 35 shown in FIG. That is, in f _rf , the capacitor 61 and the inductor 69 resonate in parallel to have a high impedance, and in f _p , the parallel resonance circuit including the capacitor 61 and the inductor 69 and the capacitor 62 resonate in series. And is designed to have low impedance. The lumped constant stub C70 is open at DC and has a high impedance. Therefore, it has the same characteristics as in FIG.

The lumped-constant stub D72 is designed to have characteristics corresponding to the tip short-circuit stub 36 of FIG. That is, in f _rf , the capacitor 71 and the inductor 67 resonate in series so as to have a low impedance, and in f _p , the series resonance circuit including the capacitor 71 and the inductor 67 and the inductor 65 resonate in parallel. And is designed to have high impedance. The lumped constant stub D72 has a low impedance due to a short circuit at DC. Therefore, it has the same characteristics as in FIG.

As described above, according to the configuration of the second embodiment, as in the case of the first embodiment, the branching circuit can be configured by the lumped constant while having the same impedance characteristics as the conventional stub. It is possible to downsize the mixer.

Example 3. FIG. 3 is a circuit diagram of the even harmonic mixer of the third embodiment. The even harmonic mixer of FIG. 3 is a combination of the lumped constant stub A64 of FIG. 1 and the lumped constant stub D72 of FIG. The even harmonic mixer of the third embodiment also has the same effect as that of the first embodiment.

Example 4. FIG. 4 is a circuit diagram of the even harmonic mixer of the fourth embodiment. The even harmonic mixer of FIG. 4 is a combination of the lumped constant stub C70 of FIG. 2 and the lumped constant stub B68 of FIG. The even harmonic mixer of the fourth embodiment also has the same effect as that of the first embodiment.

Example 5. FIG. 5 is a circuit diagram of the even harmonic mixer of the fifth embodiment. The even harmonic mixer of the fifth embodiment has a configuration in which a differential amplifier is used instead of the slot line of the even harmonic mixer of FIG.

In FIG. 5, reference numeral 86 is a differential amplifier that amplifies the local oscillation wave input to the LO terminal 33 and differentially outputs it. The differential amplifier 36 includes resistors 83a and 83b whose one ends are respectively connected to VCC, and transistors 84a and 84 whose collectors are respectively connected to the resistors 83a and 83b.
b, a current source 35 connected to the emitters of the transistors 84a and 84b. Transistor 84a
The base becomes the LO terminal. Also, the transistor 84b
The base of is grounded. The other end of the current source 85 is also grounded. The output terminals of the differential amplifier 86 are the collector of the transistor 84a and the collector of the transistor 84b.

Reference numerals 87a and 87b are DC cut capacitors provided at the output terminals of the differential amplifier 86, respectively. Reference numeral 88 denotes a mixing unit that detects a signal wave input to the RF terminal based on the output of the DC-cut differential amplifier 86 and outputs the detected signal wave to the baseband terminal 34.

The mixing section 88 is a signal wave D of the APDPs 31a to 31d and the RF terminal 32, which are connected to each other in a ring shape.
Capacitor 38 for C cut, baseband terminal 3
4 is composed of an inductor 37 for cutting high frequency signals. The APDPs 31a to 31d are connected in series. For convenience of explanation, the connection point between the APDP 31a and the APDP 31b is the D end, the connection point between the APDP 31b and the APDP 31c is the E end, and the connection point between the APDP 31c and the APDP 31d is the F end. Further, the ground ends of the APDPs 31a and 31d are referred to as the C end and the G end, respectively. The output of the differential amplifier 86 is connected to the D terminal and the F terminal, respectively. Further, the E end is connected to the RF terminal 32 and the baseband terminal 34.

Next, the operation will be described. In the differential amplifier 86, the transistors 84a and 84b are excited in opposite phases, so that the currents excited in the respective collectors are also in opposite phases. With this operation, the differential amplifier 86 can be used as a balance / unbalance converter, that is, as a substitute for a balun. In the fifth embodiment, paying attention to the fact that the slot line 80 in FIG. 12 is equivalent to a balanced line, the differential amplifier 86 is used as a balun. The operation of the mixing unit 88 is similar to that in the case of FIG.

As described above, according to the structure of the fifth embodiment, the even harmonic mixer can be formed without using the slot line, and the mixer can be downsized.

Example 6. FIG. 6 is a circuit diagram of an even harmonic mixer according to the sixth embodiment. In particular, when even-order harmonics are input to the mixer, there is a problem that suppression of the even-order harmonics of the local oscillation wave, which is an advantage of using the APDP 31, is equivalently deteriorated. Therefore, the even harmonic mixer of FIG. 6 has the differential amplifier 86 and the mixing unit 8 of the even harmonic mixer of FIG.
8, a filter 92 for removing the higher harmonic wave generated in the differential amplifier is provided.

The filter 92 includes capacitors 89a-89.
d, 90a, 90b and inductors 91a, 91b. The capacitors 89a, 90a, 89c are connected in series, and one ends of the capacitors 89a, 89c are grounded. Capacitors 89b, 90b, 8
9d is connected in series, and one ends of the capacitors 89b and 89d are grounded. Capacitors 89a, 9
The connection point with 0a and the connection points with the capacitors 89b and 90b are connected via an inductor 91b. Connection points with capacitors 90a and 89c and capacitors 90b,
The connection point with 89d is connected via an inductor 91a.

The filter 92 includes capacitors 87a, 87.
Harmonics are removed for both the in-phase mode and the anti-phase mode included in the differential output that is output via b. The capacitance of the capacitor of the filter 92 is set in consideration of this point.

As described above, according to the structure of the sixth embodiment, the even harmonic mixer can be formed without using the slot line, and the mixer can be downsized.
The harmonic components contained in the output of the differential amplifier can be removed,
The performance of the mixer is further improved.

Example 7. FIG. 7 is a circuit diagram of an even harmonic mixer using the transistor of the seventh embodiment. In FIG. 7, 18a and 18b are resistors, 19a to 19f are transistors, and 20 is a current source. RF and LO are differential inputs. Signals LO having opposite phases are supplied to the bases of the transistors 19a and 19d, respectively. The bases of the transistors 19b and 19c are grounded. Further, signals RF having opposite phases are generated by the transistors 19e and 1e.
Power is supplied to the 9f base. Transistors 19a-19
The mixed wave generated by the analog multiplication of RF and LO performed by f is output to the differential output baseband output terminal 17 connected to the collectors of the transistors 19b and 19d and the collectors of the transistors 19a and 19c, respectively.

The even harmonic mixer of FIG. 7 and the mixer of FIG. 13 differ in the excitation condition of the transistor. Transistors 19a and 19b are excited in opposite phases, and transistors 19c and 19d are excited in opposite phases. Also,
The transistors 19a and 19d are excited in opposite phases. In the even harmonic mixer of FIG. 13, the transistors 19a and 19d are excited in the same phase.

By exciting the transistors 19a and 19d in opposite phases to each other, mixing of the fundamental waves is suppressed, and an even harmonic mixer is obtained. Therefore, even if the characteristics of the transistors are not uniform, the rectified currents in the transistors are canceled out, and the DC offset does not occur. Note that RF and LO are canceled and are not output to the baseband output terminal 17.

This point will be described in more detail. As mentioned above, in the even harmonic mixer of FIG.
The base terminals of 9b and 19c are terminated to the ground, and LO is added to the transistors 19a and 19d so that they are in opposite phases. At this time, if the LO potential of the terminal 16 is ± V _LO , the base of the transistor 19a is + V
_LO , 0 [V] at the base of the transistor 19b, 0 [V] at the base of the transistor 19c, transistor 19
The base of d is supplied with -V _LO , respectively. Therefore, the signals are output in the same phase to the output terminal 17 and are not suppressed.

On the other hand, the transistors 19a, 19b, 19
In c and 19d, the second harmonic of V _LO + V _2LO is generated due to these nonlinearities. Regarding this second harmonic wave + V _2LO , the transistor 19a has + V _2LO and the transistor 1
0 [V] for 9b, 0 [V] for the transistor 19c,
+ V _2LO is generated in the transistor 19d. Therefore, the output terminal 17 has a reverse phase,
It is suppressed similarly to V _LO in FIG.

When RF is further applied to the terminal 15 and the voltage is set to ± V _rf , the differential outputs + V _rf and −V _{rf of the} differential amplifier composed of the transistors 19e and 19f become the transistors 19a and 19b and the transistors 19c and 19d. Are supplied to each. That is, the transistor 19
+ V _rf for a and 19b, transistors 19c and 19d
On the other hand, it becomes −V _rf . Therefore, the total wave multiplied by V _LO is V _LO · V _rf in the transistor 19a, 0 [V] in the transistor 19b, 0 [V] in the transistor 19c,
It becomes V _LO · V _rf at the transistor 19d. Therefore,
The output terminal 17 has a reverse phase and is suppressed.

[0074] On the other hand, mixed wave is multiplied by the V _2LO is, V _2LO · V _rf in transistor 19a, 0 in transistor 19b [V], a transistor 19c 0 [V], and -V _2LO · V _rf in transistor 19d Become. Therefore, the output terminal 17 is in phase and is not suppressed. As described above, according to the configuration of FIG. 7, even if a transistor is used, the transistor operates as an even harmonic mixer.

As described above, according to the structure of the seventh embodiment, a transistor can be used to form an even harmonic mixer, and the mixer can be miniaturized. This is particularly effective when the even harmonic mixer is constructed monolithically.

In the first to seventh embodiments, the case where the baseband output is obtained has been described as an example, but the present invention is not limited to this, and these mixers can be applied to the case where the intermediate frequency band output is obtained. .

[0077]

As described above, the claims 1 to 5 are as follows.
According to the invention of claim 2, two diodes are connected in parallel with mutually opposite polarities, and the first parallel connection end of the two diodes serves as a signal wave input end and a mixed wave output end, and a second parallel connection is made. It is composed of a diode pair whose end is an input end of the local oscillation wave and a lumped constant, and is in a short-circuit state at the frequency of the local oscillation wave and is in an open state at the frequency of the signal wave, and is in the first parallel connection. A first demultiplexing circuit connected to the end and a lumped constant, and is open at the frequency of the local oscillation wave and short-circuited at the frequency of the signal wave, and the second parallel connection end Since the second demultiplexing circuit connected to is provided, the mixer can be configured using lumped constants, and the mixer can be downsized.

According to the invention of claim 6, the differential amplifier for amplifying the locally oscillated wave and outputting it as the first output and the second output which have mutually opposite phases, and the two diodes have mutually opposite polarities. Has a diode ring configured by connecting a plurality of diode pairs each connected in parallel in a ring shape, and based on two outputs of the differential amplifier, the second harmonic of the local oscillation wave and the diode ring. Since it has a mixing section that outputs a mixed wave with the signal wave that is input to, a mixer can be configured without using a slot line,
The mixer can be miniaturized.

According to the invention of claim 7, further,
Since the filter that removes the harmonics included in the output of the differential amplifier and supplies the mixed section is provided, the harmonic components included in the output of the differential amplifier can be removed, and the mixer performance is further improved. To do.

Further, according to the invention of claim 8, a first differential amplifier for amplifying a signal wave and outputting as a first output and a second output having mutually opposite phases, and a local oscillation wave are received. Generates a second harmonic of the local oscillation wave of the lever and
A second differential amplifier that multiplies the harmonic wave by the first output of the first differential amplifier and outputs as a differential signal; and the second differential amplifier.
Second harmonic wave having an output terminal connected in parallel with the output terminal of the differential amplifier, and receiving the local oscillation wave and having a phase opposite to the second harmonic of the local oscillation wave generated in the first differential amplifier. And a third differential amplifier that generates a differential signal by multiplying the second harmonic by the second output of the first differential amplifier, and uses a differential amplifier. As a result, an even harmonic mixer can be configured, and the mixer can be downsized.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a mixer according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a mixer according to a second embodiment of the present invention.

FIG. 3 is a configuration diagram of a mixer according to a third embodiment of the present invention.

FIG. 4 is a configuration diagram of a mixer according to a fourth embodiment of the present invention.

FIG. 5 is a configuration diagram of a mixer according to a fifth embodiment of the present invention.

FIG. 6 is a configuration diagram of a mixer according to a sixth embodiment of the present invention.

FIG. 7 is a configuration diagram of a mixer according to a seventh embodiment of the present invention.

FIG. 8 is a block diagram of a conventional mixer.

FIG. 9 is a block diagram of a receiver using a mixer.

FIG. 10 is a frequency characteristic diagram of an open-ended stub.

FIG. 11 is a frequency characteristic diagram of the tip short-circuit stub.

FIG. 12 is a configuration diagram of a conventional mixer.

FIG. 13 is a block diagram of a conventional mixer.

[Explanation of symbols]

1 antenna (ANT), 2 low noise amplifier (LNA), 3 band pass filter (BPF), 60 degree distributor, 8 local oscillator, 9 low pass filter (LPF), 10 baseband amplifier (AMP), 11 Demodulation circuit, 30 mixer diode,
31 anti-parallel diode pair (APDP), 32 RF terminal, 33 LO terminal, 34 baseband terminal, 35 open-ended stub, 36 open-ended stub, 37 RF choke, 38 DC
Cut, 39 demultiplexer, 40 even harmonic mixer, 41 even harmonic quadrature mixer, 42 45 degree phase shifter, 61 capacitor Cp2
p, 62 capacitor Csp, 63 inductor Lsp, 64 lumped constant stub A, 65 inductor Lpp, 66 capacitor
Cpp, 67 Inductor Ls2p, 68 Lumped constant stub B, 69
Inductor Lp2p, 70 Lumped stub C, 71 Capacitor Cs2p, 72 Lumped stub D, 80 slot line, 81 coplanar line, 82 wire, 83 resistor, 84 transistor, 85 current source, 86 differential amplifier, 87 DC cut Capacitors, 88 mixing section.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kenji Suematsu 5-1-1, Ofuna, Kamakura-shi Electronic Systems Research Laboratories, Mitsubishi Electric Corporation (72) Akio Iida 5-1-1, Ofuna, Kamakura-shi Mitsubishi Electric Corporation Company Electronic Systems Laboratory

Claims (8)

[Claims] 1. A parallel connection of two diodes having opposite polarities, wherein a first parallel connection end of the two diodes serves as a signal wave input end and a mixed wave output end, and a second parallel connection end. And a diode pair having a local oscillation wave as an input terminal and a lumped constant, and a short-circuit state at the frequency of the local oscillation wave, an open state at the frequency of the signal wave, And a lumped constant connected to the first demultiplexing circuit, and is open at the frequency of the local oscillation wave, short-circuited at the frequency of the signal wave, and connected to the second parallel connection end. A mixer that includes a connected second demultiplexing circuit and outputs a mixed wave of the second harmonic of the local oscillation wave and the signal wave. 2. The first demultiplexing circuit is configured by a series resonance circuit including a capacitor and an inductor connected in series with each other, and a capacitor connected in parallel with the series resonance circuit. The mixer according to Item 1. 3. The first demultiplexing circuit is configured by a parallel resonant circuit including a capacitor and an inductor connected in parallel to each other, and a capacitor serially connected to the parallel resonant circuit. The mixer according to Item 1. 4. The second demultiplexing circuit is configured by a series resonance circuit including a capacitor and an inductor connected in series with each other, and an inductor connected in parallel with the series resonance circuit. The mixer according to Item 1. 5. The second demultiplexing circuit comprises a parallel resonant circuit including a capacitor and an inductor connected in parallel with each other, and an inductor serially connected to the parallel resonant circuit. The mixer according to Item 1. 6. A differential amplifier that amplifies a local oscillation wave and outputs as a first output and a second output that are in opposite phase to each other, and a plurality of diodes formed by connecting two diodes in parallel with each other in opposite polarities. It has a diode ring configured by connecting diode pairs in a ring shape, and mixes a double wave of the local oscillation wave and a signal wave input to the diode ring based on two outputs of the differential amplifier. A mixer with a mixing section that outputs waves. 7. The mixer according to claim 4, further comprising a filter that removes harmonics included in the output of the differential amplifier and supplies the harmonics to the mixer. 8. A first differential amplifier for amplifying a signal wave and outputting it as a first output and a second output having mutually opposite phases, and a second harmonic wave of the local oscillation wave when the local oscillation wave is received. And a second differential amplifier that generates a differential signal by multiplying the second harmonic by the first output of the first differential amplifier, and the output of the second differential amplifier. An output end connected in parallel with the end, receives the local oscillation wave, and generates a second harmonic having a phase opposite to the second harmonic of the local oscillation wave generated in the first differential amplifier. A third differential amplifier that multiplies the second harmonic by the second output of the first differential amplifier and outputs as a differential signal, the second harmonic of the local oscillation wave and the signal wave A mixer that outputs a mixed wave of.