JP2000244247A - Microwave mixer circuit and multi-satellite reception down converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small and inexpensive microwave mixer circuit by controlling the bias voltage to be supplied to the gate of a frequency converting FET via a simple bias switching circuit consisting of a comparator and a transistor. SOLUTION: The voltage of a high potential corresponding to the DC voltage supplied from an intermediate frequency signal output part 19 is applied to the emitter of a transistor TR 10 from a comparator 18 via a bias terminal 12. Thereby the TR 10 is turned on and an FET 8 receives the supply of the stable bias of the constant voltage/current from the TR 10 and is converted into the intermediate frequency with the satisfactory conversion gain. Then the voltage of a low potential is supplied to the emitter of a TR 11 from a comparator 17 via a bias terminal 13. Thereby, the TR 11 is turned off and an FET 9 undergoes no conversion of frequency since no bias is supplied to the FET 9. As a result, only the intermediate frequency signal that is inputted to a microwave signal input part 1 appears at the input side of an intermediate frequency amplifier 16.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave mixer circuit used for a down converter for satellite broadcasting or communication reception by a broadcasting satellite and a communication satellite, and a down converter for satellite broadcasting or communication reception provided with the down converter (international patent). Classification H01P 1/17)

2. Description of the Related Art In recent years, satellite broadcasting has reached a popularization period, and CS broadcasting using a private communication satellite has also started a service.
Opportunities for receiving multiple satellites directly in ordinary households have increased. Accordingly, miniaturization and cost reduction of the receiving antenna have been required. In the case of CS broadcasting,
Low noise down converters with a polarization switching function are the mainstream because multi-channels are performed using radio waves of the same frequency and different polarizations (horizontal polarization and vertical polarization) for effective use of frequency. It is becoming.

A conventional microwave mixer circuit will be described below with reference to FIG. FIG. 3 shows a configuration of a conventional microwave mixer circuit having a polarization switching function and an intermediate frequency amplifier. In FIG. 5, reference numerals 1 and 2 denote microwave signal input sections corresponding to horizontal and vertical polarizations.
Is a local oscillator, 4 and 5 are band-pass filters (hereinafter abbreviated as BPF) that allow local frequencies to pass, 6, 7 are microstrip lines (hereinafter abbreviated as MSL),
8, 49 are Schottky barrier diodes for frequency conversion (hereinafter abbreviated as SBD); 10, 11 are bias terminals for supplying a bias current to the anode of the SBD;
3 is a low-pass filter (hereinafter abbreviated as LPF) for passing the intermediate frequency signal, 34, 35, 36, 37 and 40;
41 is an intermediate frequency amplifier, 38 and 39 are pin diodes,
42 and 43 are transistors, 44 is a comparator, 45
Is an intermediate frequency signal output unit, and 46 and 47 are polarization switching control terminals.

The operation of the conventional microwave mixer circuit and intermediate frequency amplifier configured as described above will be described below. The 12 GHz-band microwave signals corresponding to the vertical and horizontal polarizations input to the microwave signal input units 1 and 2 are transmitted from the local oscillator 3 to the BPFs 4 and 5.
The local oscillation frequency (for example, 11.2 G
Hz) and the SBDs 48 and 49 connected to the MSLs 6 and 7, respectively, and converted into an intermediate frequency signal in the 1 GHz band. Here, the bias terminals 10 and 11 connected to the anodes of the SBDs 48 and 49 are connected to the SBDs 48 and 49 in order to prevent the conversion loss from deteriorating when the local oscillation frequency output supplied from the local oscillator 3 is small.
And 49 are applied with a forward bias current. L
The intermediate frequency signals that have passed through the PFs 12 and 13 are amplified by intermediate frequency amplifiers 34 and 35 and 36 and 37, and pass through pin diodes 38 and 39. The current supply terminals of the intermediate frequency amplifiers 34 and 35 and the pin diodes 38
Is connected to a polarization switching control terminal 46. The polarization switching terminal 46 is connected to a DC voltage (for example, 11 V or 15 V) externally supplied from the intermediate frequency signal output unit 45.
V), a comparator 44 for outputting different binary DC signals according to V) and a transistor 4 for connecting the output to the base.
2 collector. Similarly, the current supply terminals of the intermediate frequency amplifiers 36 and 37 and the anode of the pin diode 39 are connected to the emitter of the transistor 43 via the polarization switching control terminal 47. In the above configuration, when a DC voltage of 11 V is supplied from the intermediate frequency signal output unit 45, the transistor 42 is turned on and the transistor 43 is turned off at the same time. Therefore, the intermediate frequency amplifier 3
4 and 35 and the pin diode 38 are turned on, and the intermediate frequency amplifiers 36 and 37 and the pin diode 39 are turned off. Therefore, the vertically polarized microwave input from the microwave signal input unit 1 is applied to the intermediate frequency amplifiers 40 and 41. An intermediate frequency signal corresponding to the signal is supplied, amplified to a desired level, and then extracted from the intermediate frequency signal output unit 45. Similarly, when a DC voltage of 15 V is supplied from the intermediate frequency signal output unit 45, an intermediate frequency signal corresponding to the horizontally polarized microwave signal input from the microwave signal input unit 2 is extracted.

[0004]

However, in the above-mentioned conventional configuration, the intermediate frequency amplifiers 34 corresponding to the microwave signal input sections 1 and 2 to which two different polarized waves are input are provided.
Since 35, 36, and 37 and pin diodes 38 and 39 are required, it is difficult to reduce the size and disadvantageously in terms of cost.

An object of the present invention is to solve the above-mentioned conventional problems and to provide a small and inexpensive microwave mixer circuit and down converter.

[0006]

In order to achieve these objects, a microwave mixer circuit and a down converter according to the present invention use a simple method using a comparator and a transistor to supply a bias voltage supplied to the gate of a frequency conversion FET. It is characterized in that two different microwave signals are selected by being controlled by a bias switching circuit and converted into an intermediate frequency signal.

According to the present invention, by controlling the emitter bias voltage of the bias supply transistor of two or more different frequency conversion FETs, when the emitter bias voltage is higher than the base bias, that is, when the transistor is on, the FET is turned on. When a constant voltage and constant current bias is supplied to the transistor and the nonlinear operation is performed, a good conversion gain is obtained. When the emitter bias voltage is lower than the base bias, that is, when the transistor is off, no bias is supplied to the FET and the nonlinear operation is performed. Is not performed, a plurality of microwave signal inputs can be selected and converted to an intermediate frequency signal due to the property that frequency conversion is not performed.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the first aspect of the present invention, a plurality of microwave signal input sections formed on a dielectric substrate by microstrip lines, and a gate is connected to each end thereof. An FET whose source is grounded;
A transistor having a collector connected to the gate of the ET and an emitter connected to the drain, a bias terminal for supplying a bias voltage to the emitter of the transistor, and a bias switching circuit for controlling a bias voltage supplied to the bias terminal;
A microwave mixer circuit having a common intermediate frequency signal output unit for connecting the drains of the respective FETs to obtain an intermediate frequency signal, wherein two or more different frequency conversion FEs are provided.
By controlling the emitter bias voltage of the T bias supply transistor, when the emitter bias voltage is higher than the base bias, that is, when the transistor is turned on, a constant voltage / constant current bias is supplied to the FET and the nonlinear operation is performed. When the emitter bias voltage is lower than the base bias, that is, when the transistor is off, the bias is not supplied to the FET and the nonlinear operation is not performed. It has the effect that it can be selected and converted to an intermediate frequency signal.

According to a second aspect of the present invention, there is provided the microwave mixer circuit according to the first aspect, further comprising a Wilkinson-type divider between the drain of each FET and the intermediate frequency signal output section, By controlling the emitter bias voltage of the bias supply transistor of two or more different frequency conversion FETs, a constant voltage constant current bias is supplied to the FET when the emitter bias voltage is higher than the base bias, that is, when the transistor is on. When the nonlinear operation is performed, a good conversion gain is obtained, and when the emitter bias voltage is lower than the base bias, that is, when the transistor is off, no bias is supplied to the FET and the nonlinear operation is not performed. To select multiple microwave signal inputs and And it can be converted, an effect that isolation of different microwave signal can be easily obtained.

[0010] The invention according to claim 3 of the present invention provides a 12G
A probe for converting a microwave signal in the Hz band into a TEM wave, a plurality of low-noise amplifiers, a plurality of microstrip lines, an FET having a gate connected to the terminal of each of the microstrip lines and a source grounded, The above FE
A transistor having a collector connected to the gate of T and an emitter connected to the drain; a bias terminal for supplying a bias voltage to the emitter of the transistor; a bias switching circuit for controlling a bias voltage supplied to the bias terminal; A downconverter including a common intermediate frequency signal output unit for obtaining an intermediate frequency signal by connecting a drain, and controlling an emitter bias voltage of a bias supply transistor of two or more different frequency conversion FETs to thereby obtain an emitter. When the bias voltage is higher than the base bias, that is, when the transistor is on, F
A good conversion gain is obtained by supplying a constant voltage and constant current bias to the ET and performing a non-linear operation. When the emitter bias voltage is lower than the base bias, that is, when the transistor is off, no bias is supplied to the FET and the non-linear operation is performed. The function of selecting a plurality of microwave signal inputs and converting them to an intermediate frequency signal by the property of not being frequency-converted because the operation is not performed, and that isolation of different microwave signals can be easily obtained. Having.

According to a fourth aspect of the present invention, there are provided two waveguide inputs corresponding to two different satellites,
a probe for converting a z-band microwave signal into a TEM wave, a plurality of low-noise amplifiers, a plurality of microstrip lines, an FET having a gate connected to the terminal of each of the microstrip lines and a source grounded, The above FE
A transistor having a collector connected to the gate of T and an emitter connected to the drain; a bias terminal for supplying a bias voltage to the emitter of the transistor; and a pulse superimposed on a bias voltage supplied to the bias terminal on an externally supplied DC power supply A multi-satellite reception downconverter comprising a bias switching circuit controlled by a signal and a common intermediate frequency signal output unit for connecting the drains of the respective FETs to obtain an intermediate frequency signal, wherein two or more different frequency conversion FETs are provided. By controlling the emitter bias voltage of the bias supply transistor, when the emitter bias voltage is higher than the base bias, that is, when the transistor is turned on, a constant voltage / constant current bias is supplied to the FET and the non-linear operation is performed. Conversion gain is obtained and the emitter via When the voltage is lower than the base bias, that is, when the transistor is turned off, the bias is not supplied to the FET and the nonlinear operation is not performed. Can be controlled,
In addition, there is an effect that isolation of different microwave signals can be easily obtained. Hereinafter, embodiments of the present invention will be described with reference to FIGS.

(Embodiment 1) FIG. 1 is a circuit pattern diagram of a microwave mixer circuit and an intermediate frequency amplifier according to a first embodiment of the present invention.

In FIG. 1, 1 and 2 are microwave signal input sections corresponding to vertical and horizontal polarizations, 3 is a local oscillator, 4 and 5 are BPs for passing local frequencies.
F, 6, 7 are MSL, 8, 9 are GaAsF for frequency conversion.
ET (hereinafter abbreviated as FET), 12 and 13 are transistors for supplying a bias voltage to the gate and drain of the FET, 10 and 11 are bias terminals for supplying a bias voltage to the emitter of the transistor, and 14 and 15 are intermediate frequency signals. LPF, 16 is an intermediate frequency amplifier, 17 and 18 are comparators constituting a bias switching circuit for switching a bias voltage supplied to bias terminals 10 and 11,
Reference numeral 19 denotes an intermediate frequency signal output unit which outputs an intermediate frequency signal and receives a polarization switching control signal (for example, a DC voltage of 11 V or 15 V) from the outside (for example, a satellite reception tuner).
Is supplied.

The operation of the microwave mixer circuit and the intermediate frequency amplifier configured as described above will be described below. First, a case where a DC voltage of 15 V is supplied to the intermediate frequency signal output unit 19 will be described. 12 GHz corresponding to the horizontal polarization input to the microwave signal input unit 1
The microwave signal of the band is connected to the FET8 connected to the MSL6.
And a local oscillation frequency (for example, 11.2 GHz) supplied from the local oscillator 3 through the BPF 4.
z). The collector of the transistor 12 is connected to the gate of the FET 8 connected to the MSL 6, and the emitter of the transistor 12 is connected to the drain of the FET 8. The HI corresponding to the DC voltage of 15 V supplied from the intermediate frequency signal output unit 19 is connected to the emitter of the transistor 12.
The voltage of the GH potential is supplied from the comparator 18 to the bias terminal 1
0, the transistor 12 is turned on, and the FET 8 is supplied with a stable bias of constant voltage and constant current from the transistor 12 and is converted to a 1 GHz band intermediate frequency signal with a good conversion gain, and the LPF 14 is turned on. After passing, it is guided to the intermediate frequency amplifier 16. On the other hand, 1 corresponding to the vertical polarization input to the microwave signal input unit 2
The microwave signal in the 2 GHz band is transmitted to the FSL connected to the MSL7.
It is led to the gate of ET, and BPF5
The local oscillation frequency (for example, 11.2 G
Hz), but the comparator 17 outputs the LO signal to the emitter of the transistor 13 through the bias terminal 11.
Since the voltage of the W potential is supplied, the transistor 13 is turned off, and no bias is supplied to the FET 9, so that no frequency conversion is performed. Therefore, the intermediate frequency amplifier 16
On the input side, only the 1 GHz band intermediate frequency signal corresponding to the horizontal polarization input to the microwave signal input unit 1 appears.
After being amplified to a desired level by the intermediate frequency amplifier 16,
It is extracted from the intermediate frequency signal output unit 19. Similarly, when a DC voltage of 11 V is supplied from the intermediate frequency signal output unit 19, the bias current of the FET 9 is turned on and the bias current of the FET 8 is turned off at the same time. Is extracted from the intermediate frequency signal output unit 19.

(Embodiment 2) FIG. 2 is a circuit pattern diagram of a microwave mixer circuit and an intermediate frequency amplifier according to a second embodiment of the present invention.

In FIG. 2, 1 and 2 are microwave signal input sections corresponding to vertical and horizontal polarizations, 3 is a local oscillator, 4 and 5 are BPs for passing local frequencies.
F, 6, 7 are MSL, 8, 9 are GaAsF for frequency conversion.
ET (hereinafter abbreviated as FET), 12 and 13 are transistors for supplying a bias voltage to the gate and drain of the FET, 10 and 11 are bias terminals for supplying a bias voltage to the emitter of the transistor, and 14 and 15 are intermediate frequency signals. LPF, 16 is an intermediate frequency amplifier, 17 and 18 are comparators constituting a bias switching circuit for switching a bias voltage supplied to bias terminals 10 and 11,
Reference numeral 19 denotes an intermediate frequency signal output unit which outputs an intermediate frequency signal and receives a polarization switching control signal (for example, a DC voltage of 11 V or 15 V) from the outside (for example, a satellite reception tuner).
Is supplied. 20 is absorption resistance, 21 and 22 are 1 GH
MS having a line length of 1/4 of the wavelength of the z-band intermediate frequency signal
L. The operation of the microwave mixer circuit and the intermediate frequency amplifier configured as described above will be described below. First, a case where a DC voltage of 15 V is supplied to the intermediate frequency signal output unit 19 will be described. The microwave signal of 12 GHz band corresponding to the horizontal polarization input to the microwave signal input unit 1 is guided to the gate of the FET 8 connected to the MSL 6, and the local oscillation frequency supplied from the local oscillator 3 via the BPF 4. (For example, 11.2 GHz)
Mixed with. The collector of the transistor 12 is connected to the gate of the FET 8 connected to the MSL 6, and the emitter of the transistor 12 is connected to the drain of the FET 8. An intermediate frequency signal output unit 19 is connected to the emitter of the transistor 12.
When a HIGH potential voltage corresponding to the supplied DC voltage of 15 V is applied from the comparator 18 via the bias terminal 10, the transistor 12 is turned on, and the FET 8 is switched from the transistor 12 to a stable constant voltage and constant current. 1 with good conversion gain when supplied with bias
After being converted into an intermediate frequency signal in the GHz band and passing through the LPF 14, the signal is guided to the intermediate frequency amplifier 16. On the other hand, 12G corresponding to the vertical polarization input to the microwave signal input unit 2
Hz band microwave signal is connected to MSL7 FET
And a local oscillation frequency (for example, 11.2 GHz) supplied from the local oscillator 3 through the BPF 5.
z), but the emitter of the transistor 13 is LOW from the comparator 17 via the bias terminal 11.
Since the potential voltage is supplied, the transistor 13 is turned off, and no frequency conversion is performed because no bias is supplied to the FET 9. The MSL 21 and the MSL 22 together with the absorption resistor 20 constitute a Wilkinson-type divider, and ensure isolation between the respective lines. Therefore, the input side of the intermediate frequency amplifier 16 has a 1G signal corresponding to the horizontal polarization input to the microwave signal input unit 1.
Only the intermediate frequency signal in the Hz band appears, and the intermediate frequency amplifier 16
After being amplified to a desired level, the signal is extracted from the intermediate frequency signal output unit 19. Similarly, the intermediate frequency signal output unit 1
When a DC voltage of 11 V is supplied from 9, the FET
Since the bias current of the FET 8 is turned off at the same time when the bias current of the FET 9 is turned on, an intermediate frequency signal corresponding to vertical polarization is extracted from the intermediate frequency signal output unit 19.

(Embodiment 3) FIG. 3 shows a circuit pattern diagram of a down converter according to a third embodiment of the present invention.

In FIG. 3, reference numerals 23 and 24 denote probes for converting a microwave signal of 12 GHz band radiated from a satellite in vertical and horizontal polarization planes into a quasi-TEM wave propagating through a microstrip line.
7, 28 are low-noise amplifiers composed of low-noise elements such as HEMTs, 3 is a local oscillator, 4 and 5 are BPFs that pass local frequencies, 6, 7 are MSL, 8, 9 are GaAs FETs for frequency conversion. (Hereinafter abbreviated as FET), 12,
Reference numeral 13 denotes a transistor for supplying a bias voltage to the gate and drain of the FET. Reference numerals 10 and 11 denote bias terminals for supplying a bias voltage to the emitter of the transistor.
5, an LPF for passing an intermediate frequency signal; 16, an intermediate frequency amplifier; 17 and 18, comparators constituting a bias switching circuit for turning on / off a bias current supplied to bias terminals 10 and 11; 19, an intermediate frequency signal output unit In addition to outputting the intermediate frequency signal, a polarization switching control signal (for example, a DC voltage of 11 V or 15 V) is supplied from the outside (for example, a tuner for satellite reception). Reference numeral 20 denotes an absorption resistor, and reference numerals 21 and 22 denote MSLs having a line length of 1/4 of the wavelength of the 1 GHz band intermediate frequency signal.

The operation of the down converter configured as described above will be described below. First, a case where a DC voltage of 15 V is supplied to the intermediate frequency signal output unit 19 will be described. The horizontally polarized microwave signal radiated from the satellite is converted into a quasi-TEM wave propagating through the microstrip line by the probe 23 and is amplified by the low noise amplifiers 25 and 26 with low noise. And a local oscillation frequency (for example, 11.2 GHz) supplied thereto. The collector of the transistor 12 is connected to the gate of the FET 8 connected to the MSL 6, and the emitter of the transistor 12 is connected to the drain of the FET 8. A HIGH voltage corresponding to a DC voltage of 15 V supplied from the intermediate frequency signal output unit 19 is supplied to the emitter of the transistor 12 by the comparator 18.
By being applied through the bias terminal 10,
The transistor 12 is turned on, and the FET 8 is supplied with a stable bias of constant voltage and constant current from the transistor 12, is converted into an intermediate frequency signal of 1 GHz band with a good conversion gain, passes through the LPF 14, and is led to the intermediate frequency amplifier 16. I will On the other hand, the microwave signal of the 12 GHz band corresponding to the vertical polarization input to the microwave signal input unit 2 is MS
It is guided to the gate of the FET connected to L7 and mixed with the local oscillation frequency (for example, 11.2 GHz) supplied from the local oscillator 3 via the BPF 5. , The transistor 13 is turned off, and the bias is not supplied to the FET 9, so that the frequency conversion is not performed. MSL2
1 and the MSL 22 together with the absorption resistor 20 constitute a Wilkinson-type divider and ensure isolation between the respective lines. Therefore, the intermediate frequency amplifier 1
On the input side of 6, only the 1 GHz band intermediate frequency signal corresponding to the horizontal polarization input to the probe 23 appears. After being amplified to a desired level by the intermediate frequency amplifier 16, it is extracted from the intermediate frequency signal output unit 19. It is. Similarly, when a DC voltage of 11 V is supplied from the intermediate frequency signal output unit 19, the FE is simultaneously turned on when the bias current of the FET 9 is turned on.
Since the bias current at T8 is turned off, an intermediate frequency signal corresponding to the vertical polarization is extracted from the intermediate frequency signal output unit 19.

(Embodiment 4) FIG. 4 is a circuit pattern diagram of a multi-satellite reception down converter according to a fourth embodiment of the present invention.

In FIG. 4, reference numerals 36 and 37 denote waveguide inputs 23, 24 and 3 corresponding to two different satellites.
Reference numerals 0 and 31 denote probes for converting a microwave signal in the 12 GHz band radiated from the satellite on the vertical and horizontal polarization planes into a quasi-TEM wave propagating through a microstrip line.
5, 26 and 27 and 28 are low noise amplifiers composed of low noise elements such as HEMTs, 3 is a local oscillator,
5 is a BPF for passing a local frequency, and 6 and 7 are MSs.
L, 8, and 9 are GaAs FETs for frequency conversion (hereinafter referred to as FETs).
, 12 and 13 are transistors for supplying a bias voltage to the gate and drain of the FET, 10 and 11 are bias terminals for supplying a bias voltage to the emitter of the transistor, and 14 and 15 are LPs for passing an intermediate frequency signal.
F and 16 are intermediate frequency amplifiers, 17 and 18 are comparators constituting a bias switching circuit for turning on / off a bias current supplied to the bias terminals 10 and 11, and 19 is an intermediate frequency signal output unit for outputting an intermediate frequency signal. At the same time, a polarization switching control signal (for example, a DC voltage of 11 V or 15 V) is supplied from outside (for example, a satellite reception tuner). Reference numeral 20 denotes an absorption resistor, and reference numerals 21 and 22 denote MSLs having a line length of 1/4 of the wavelength of the 1 GHz band intermediate frequency signal. 35 is a low-noise amplifier 2 based on the polarization switching control signal.
A polarization switching control circuit for controlling ON / OFF of 5, 29 and 27, 28; MSL 33, 34; and a satellite switching signal (for example, a pulse of 32 kHz to 53 kHz) externally supplied to the intermediate frequency signal output unit 19. A band-pass filter (hereinafter abbreviated as BPF) 39 for extracting and amplifying a pulse signal from the BPF and converting the pulse signal into a DC voltage.

The operation of the multi-satellite reception down-converter configured as described above will be described below. First, a DC voltage of 15V is supplied to the intermediate frequency signal output unit 19,
The case where the satellite corresponding to the waveguide input unit 36 is received will be described. Horizontally polarized microwave signals emitted from two different satellites are converted into quasi-TEM waves propagating through a microstrip line by probes 23 and 31 located inside waveguide input sections 36 and 37, respectively. 15 supplied to the intermediate frequency signal output unit 19
After being amplified by the low noise amplifiers 25 and 29 selected by the polarization switching control circuit 35 by the V polarization switching signal, the signal passes through the MSL 33 and the MSL 34, and is further amplified by the low noise amplifiers 26 and 30. And MS
It is guided to the gate of the FET 8 connected to L6, and is mixed with the local oscillation frequency (for example, 11.2 GHz) supplied from the local oscillator 3 via the BPF 4. The collector of the transistor 12 is connected to the gate of the FET 8 connected to the MSL 6, and the emitter of the transistor 12 is connected to the drain of the FET 8. A satellite switching signal (for example, a 32 kHz to 53 kHz pulse signal) superimposed on a 15 V DC voltage supplied from the intermediate frequency signal output unit 19 is a BP signal.
After being extracted by F38 and amplified at the same time, it is converted into a DC voltage by the detection circuit 39 and sent to the comparator 18. As a result, a HIGH potential voltage corresponding to the DC voltage of 15 V supplied from the intermediate frequency signal output unit 19 is applied to the emitter of the transistor 12 from the comparator 18 via the bias terminal 10, so that the transistor 12 is turned on. The FET 8 is supplied with a stable bias of a constant voltage and a constant current from the transistor 12, is converted into a 1 GHz band intermediate frequency signal with a good conversion gain, passes through the LPF 14, and is guided to the intermediate frequency amplifier 16. On the other hand, the microwave signal of the 12 GHz band corresponding to the vertical polarization input to the microwave signal input unit 2 is MSL.
7 is mixed with the local oscillation frequency (for example, 11.2 GHz) supplied from the local oscillator 3 via the BPF 5 to the gate of the FET connected to the FET 7. , The transistor 13 is turned off, and the bias is not supplied to the FET 9, so that the frequency conversion is not performed. MSL2
1 and the MSL 22 together with the absorption resistor 20 constitute a Wilkinson-type divider and ensure isolation between the respective lines. Therefore, the intermediate frequency amplifier 1
On the input side of 6, only the 1 GHz band intermediate frequency signal corresponding to the horizontal polarization of the satellite corresponding to the waveguide input section 36 appears.
After being amplified to a desired level by the intermediate frequency amplifier 16,
It is extracted from the intermediate frequency signal output unit 19. Similarly, when the satellite switching signal is not supplied to the intermediate frequency signal output unit 19, the bias current of the FET 9 is turned on and the bias current of the FET 8 is turned off at the same time. Signal is intermediate frequency signal output unit 1
9

[0023]

As described above, the present invention provides a frequency conversion F
By adding a bias terminal that supplies a bias to the gate of the ET and a bias switching circuit with a simple configuration that controls the bias voltage supplied to the bias terminal, a desired signal can be selected from a plurality of input microwave signals. An inexpensive and compact microwave mixer and down converter capable of converting to an intermediate frequency signal are realized.

[Brief description of the drawings]

FIG. 1 is a circuit pattern diagram of a microwave mixer circuit according to a first embodiment of the present invention.

FIG. 2 is a circuit pattern diagram of a microwave mixer circuit according to a second embodiment of the present invention.

FIG. 3 is a circuit pattern diagram of a down converter according to a third embodiment of the present invention.

FIG. 4 is a circuit pattern diagram of a multi-satellite reception down converter according to a fourth embodiment of the present invention.

FIG. 5 is a circuit pattern diagram of a conventional microwave mixer circuit.

[Explanation of symbols]

 1, 2 Microwave signal input unit 3 Local oscillator 4, 5, 38 BPF 6, 7, 21, 22, 33, 34 MSL 8, 9 GaAs FET 10, 11 Bias terminal 12, 13 Transistor 14, 15 LPF 16 Intermediate frequency amplifier 17, 18 Comparator 19 Intermediate frequency signal output unit 20 Absorption resistor 23, 24, 31, 32 Probe 25, 26, 27, 28, 29, 30 Low noise amplifier 35 Polarization switching control circuit 36, 37 Waveguide input unit 39 Detection circuit

Claims (4)

[Claims] 1. A plurality of microwave signal input sections formed by microstrip lines on a dielectric substrate, and FETs each having a gate connected to a terminating end and a source grounded.
A transistor having a collector connected to the gate of the FET and an emitter connected to the drain, a bias terminal for supplying a bias voltage to the emitter of the transistor, a bias switching circuit for controlling a bias voltage supplied to the bias terminal, A microwave mixer circuit having a common intermediate frequency signal output by connecting the drains of FETs. 2. The microwave mixer circuit according to claim 1, further comprising a Wilkinson divider between the drain of each FET and the intermediate frequency signal output section. 3. A TEM using a microwave signal of 12 GHz band.
A probe for converting to a wave, a plurality of low-noise amplifiers, a plurality of microstrip lines, an FET having a gate connected to the end of each microstrip line and a source grounded, and a collector connected to the gate of the FET A transistor having a drain connected to the emitter, a bias terminal for supplying a bias voltage to the emitter of the transistor, a bias switching circuit for controlling a bias voltage supplied to the bias terminal, and an intermediate frequency connected to the drain of each of the FETs. A down converter including a common intermediate frequency signal output unit for obtaining a signal. 4. A plurality of waveguide input sections corresponding to two different satellites, a probe for converting a microwave signal in a 12 GHz band into a TEM wave, a plurality of low noise amplifiers, a plurality of microstrip lines, An FET having a gate connected to the end of each microstrip line and a source grounded; a transistor having a collector connected to the gate of the FET and having an emitter connected to the drain; and a bias terminal for supplying a bias voltage to the emitter of the transistor. A bias switching circuit for controlling a bias voltage supplied to a bias terminal by a pulse signal superimposed on an externally supplied DC power supply, and a common intermediate frequency signal for connecting the drains of the respective FETs to obtain an intermediate frequency signal A multi-satellite reception down converter having an output unit.