JP3186949B2 - Low noise block down converter circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a converter circuit as a component of a satellite broadcast receiver, and more particularly, to a dual polarity dual band low noise block down converter circuit.

[0002]

2. Description of the Related Art FIG. 11 shows a typical satellite broadcast receiving apparatus. This satellite broadcast receiving device includes an outdoor unit OD and an indoor unit ID. The outdoor unit OD has an antenna 101 and a low noise block down converter 102 connected to the antenna 101. The converter 102 has a function of amplifying a weak radio wave from a satellite caught by the antenna 101 with low noise and supplying a low-noise and sufficient-level signal to the indoor receiver 104. The converter 102 is a coaxial cable 1
03 is connected to the indoor receiver 104.

[0003] The indoor unit ID is the indoor receiver 10.
4 and the television 109. The indoor receiver 104 includes a DBS (dual band satellite) tuner 105, an FM (frequency modulation) demodulator 106, a video and audio circuit 107, and an RF (high frequency) modulator 1
08. The signal from the coaxial cable 103 is signal-processed by the indoor receiver 104 and output from the indoor receiver 104 to the television 109.

FIG. 12 shows a conventional dual polarity dual band low noise block down converter 10.
2 shows a circuit configuration of FIG. This low noise block down converter 102 receives signals in two different frequency bands from the Ku band satellite in the United States. The two different frequency bands are the FSS frequency band and the BSS frequency band. FSS is a fixed satellite (Satell)
ITE) service (Service), and BSS is an abbreviation of broadcast (Satellite) service (Service). The FSS frequency band is a frequency band from 11.7 GHz to 12.2 GHz, and the BSS frequency band is from 12.2 GHz to 1 GHz.
It is a frequency band up to 2.7 GHz. The FSS uses a horizontal polarization signal and a vertical polarization signal, and the BSS uses a right-hand polarization signal and a left-hand polarization signal.

[0005] The converter 102 is a low noise amplifier 12 to which a horizontally polarized signal or a right-handed polarized signal is input.
1 and a low noise amplifier 122 to which a vertically polarized signal or a left-handed polarized signal is input. The low-noise amplifiers 121 and 122 are low-noise amplifiers.
It has three amplifiers composed of stages. These low-noise amplifiers 121 and 122 are 11.7 GHz to 1
The 2.7 GHz input signal is amplified with low noise by about 27 dB. The low noise amplifier 121 includes a Y-type distribution circuit 12.
3 is connected, and the Y-type distribution circuit 124 is connected to the low noise amplifier 122. The Y-type distribution circuit 123 is connected to band-pass filters 125 and 126 as image removal filters. The mixer 127 is connected to the bandpass filter 125. A mixer 128 is connected to the band pass filter 126.

On the other hand, bandpass filters 131 and 132 are connected to the Y-type distribution circuit 124. The mixer 133 is connected to the bandpass filter 131, and the mixer 1 is connected to the bandpass filter 132.
34 are connected.

Further, the four mixers 127, 12
8, 133, 134 are connected to the IF preamplifier 135. And, this IF preamplifier 135 has two IF
It is connected to switches 136 and 137. The IF switches 136 and 137 are connected to IF amplifiers 140 and 141. And this IF amplifier 14
0 and 141 are connected to output terminals 142 and 143.

When the converter 102 receives the horizontal polarization signal and the vertical polarization signal in the FSS frequency band, a DC signal of 9 V or more is applied to an output terminal 142 of the converter 102 as a control signal. Then, the control signal of 9 V or more is input to the comparator CPM, and the comparator CPM sets the switch SW and the IF switches 136 and 137 to the switching state shown in FIG. Then, a supply voltage of 5 V is applied from the 5 V power supply 145 to the local oscillator LO1. Then, the local oscillator LO1 oscillates a signal having a frequency of 10.75 GHz, and outputs the oscillation signal having the frequency of 10.75 GHz to the mixers 127 and 133. Then, this mixer 127
Mixes a horizontally polarized signal received through a low-noise amplifier 121, a Y-type distribution circuit 123, and a band-pass filter 125 in order with an oscillation signal of 10.75 GHz,
The signal is output to the amplifier 135A included in the preamplifier 135. Then, the amplifier 135A amplifies the mixed signal and outputs the amplified signal to the IF switch 136 as an IF signal. The IF signal is 950-1450M
Hz, from the IF switch 136 to the IF amplifier 140
And is amplified to a predetermined level by the IF amplifier 140 before being output to the output terminal 142.

The vertically polarized signal is supplied to a low-noise amplifier 122, a Y-type distribution circuit 124, and a band-pass filter 1.
31 and input to the mixer 133. And
The mixer 133 receives the signal from the local oscillator LO1.
The 0.75 GHz oscillation signal and the vertical polarization signal are mixed and output to the IF preamplifier 135. The mixed signal of the vertically polarized signal and the oscillation signal is supplied to the output terminal 14 via the IF switch 137 and the IF amplifier 141.
3 is output.

On the other hand, the converter 102 is connected to the BS
When receiving a right-handed polarization signal and a left-handed polarization signal in the S frequency band, a DC signal of 7 V or less as a control signal is applied to output terminal 142 of converter 102. Then, the control signal of 7 V or less is input to the comparator CPM, and the comparator CPM switches the switch SW and the IF switches 136 and 137 from the switching state shown in FIG. Then, a supply voltage of 5 V is applied from the 5 V power supply 145 to the local oscillator LO2. Then, local oscillator LO2 oscillates a signal having a frequency of 11.25 GHz, and outputs the oscillated signal having the frequency of 11.25 GHz to mixers 128 and 134. Then, the mixer 128 mixes the right-handed polarized signal received through the low-noise amplifier 121, the Y-type distribution circuit 123, and the band-pass filter 126 in order with the oscillation signal of 11.25 GHz to produce a 950-1450 MHz Is output to the amplifier 135B included in the IF preamplifier 135.
Then, the amplifier 135B amplifies the IF signal and outputs it to the IF switch 136. And the above IF
The signal is output from the IF switch 136 to the IF amplifier 140, and is output from the IF amplifier 140 to the output terminal 142.

The left-handed polarization signal is supplied to a low-noise amplifier 122, a Y-type distribution circuit 124, and a band-pass filter 1.
32 and input to the mixer 134. And
This mixer 134 receives 1 from the local oscillator LO2.
The 1.25 GHz oscillation signal is mixed with the left-handed polarization signal, and an IF signal of 950 to 1450 MHz is output to the IF preamplifier 135. The IF signal as a mixed signal of the left-handed polarization signal and the oscillation signal is output to an output terminal 14 via an IF switch 137 and an IF amplifier 141.
3 is output.

Thus, the dual polarity dual band low noise block down converter 10
The switch SW and the IF switches 136 and 137 are used for receiving a horizontal polarization signal and a vertical polarization signal in the FSS, and for receiving a right-hand polarization signal and a left-hand polarization signal in the BSS. Switching and signal conversion.

[0013]

However, the above-mentioned conventional dual polarity dual band low noise block down converter has the following problems.

Since the outputs of the low-noise amplifiers 121 and 122 are divided into two by the Y-type distribution circuits 123 and 124, the noise figures (N
oiseFigure) NF gets worse by the loss due to this two distribution. Therefore, in order to compensate for this loss, it is necessary to configure the low noise amplifiers 121 and 122 with three HEMT stages. That is, by increasing the gain of the low noise amplifier as much as possible, the overall noise figure (Noise Figure) characteristic of the LNB (low noise block down converter) is reduced to the noise of the Y-type distribution circuit, band pass filter, mixer, IF preamplifier after the low noise amplifier. I try not to be affected by the figure characteristics. As described above, since the number of HEMT elements constituting the low-noise amplifier is large, there is a problem that the cost is high.

To convert the horizontal polarization signal, the vertical polarization signal, the right-hand polarization signal, and the left-hand polarization signal, each signal requires dedicated mixers 127, 133, 128, and 134. Therefore, there is a disadvantage that expensive semiconductor elements such as HEMT elements or diode mixer elements increase.

Further, since the IF preamplifier needs to be provided with four amplifiers dedicated to each of the signals, there is a problem that the cost is increased and the structure is complicated.

Further, since two IF switches 136 and 137 for connecting between the four amplifiers and switching between the case of the FSS and the case of the BSS are required, the cost is increased and the structure is complicated. There's a problem.

Further, since the number of components is increased due to the above, there is also a problem that the size of a circuit board on which the components are mounted becomes large.

Therefore, an object of the present invention is to provide the following [1],
An object of the present invention is to provide a low-noise block downconverter circuit capable of achieving [2] and [3].

[1] FSS (Fixed Satellite) service and BSS (Broadcast) whose input frequencies are becoming mainstream in the United States from 11.7 GHz to 12.7 GHz
ast) To realize a low noise block down converter for both satellite and service in a compact size and shape that does not impair the aesthetic appearance.

[2] To realize a low-noise block down-converter circuit with high cost performance.

[3] A reduction in the number of parts is achieved, and mass productivity and reliability are improved.

[0023]

To achieve the above object, according to the present invention, a first low-noise amplifier and a signal received from the first low-noise amplifier and having a predetermined band are received. A first band-pass filter that outputs a signal, a first mixer that converts a signal of a predetermined band output from the first band-pass filter into an IF (intermediate frequency) signal and outputs the IF signal, A first offset ring filter, a second low-noise amplifier, and a second band-pass receiving a signal from the second low-noise amplifier and outputting a signal in a predetermined band. A filter, a second mixer for converting a signal of a predetermined band output from the second band-pass filter into an IF signal and outputting the IF signal, and a second offset ring filter connected to the second mixer And input A first local oscillator for oscillating a signal of a first frequency and a first local oscillator for oscillating a signal of a first frequency. The first output terminal is connected to the first offset ring filter, and the second output terminal is connected to a second local oscillator that oscillates a signal having a second frequency different from the first output terminal. A distributor connected to a second offset ring filter, wherein the first offset ring filter and the second offset ring filter are connected to the first frequency and the second frequency.
Is characterized in that a frequency component intermediate with the frequency of (1) is set as the peak of the pass characteristic.

According to a second aspect of the present invention, there is provided a low noise block down converter circuit according to the first aspect,
A buffer amplifier is connected between the first local oscillator, the second local oscillator, and the distributor.

According to a third aspect of the present invention, there is provided a low noise block down converter circuit according to the first aspect,
It is characterized by comprising a first band-pass filter connected to the output terminal of the first local oscillator and a second band-pass filter connected to the output terminal of the second local oscillator.

According to a fourth aspect of the present invention, there is provided the low noise block down converter circuit according to the first aspect,
A first stub element connected between the first output terminal of the distributor and the first offset ring filter, and a first stub element connected between the second output terminal of the distributor and the second offset ring filter; And a second stub element connected thereto, and RF signals from the first and second offset ring filters are provided.
The input signal is trapped by the first and second stub elements.

According to a fifth aspect of the present invention, there is provided the low noise block down converter circuit according to the first aspect,
The first mixer and the second mixer are characterized in that they are active mixers having a conversion gain. According to a sixth aspect of the present invention, in the low noise block downconverter circuit according to any one of the first to fifth aspects, an IF (intermediate frequency) is connected to the output terminals of the first mixer and the second mixer, respectively. ) An amplifier is connected, and a temperature compensation circuit is connected to each of the IF amplifiers.

[0028]

The dual-polarity dual-band low-noise block downconverter circuit according to the present invention is a converter circuit for converting signals in two frequency bands. When converting a signal in one frequency band, the converter circuit performs signal conversion using a local oscillation signal of a first frequency oscillated by a first local oscillator. Also, when converting the signal of the other frequency band,
Signal conversion is performed using the local oscillation signal of the second frequency oscillated by the second local oscillator.

The signal in the one frequency band includes two types of polarization signals having different polarization directions. The signals in the other frequency band have different polarization directions.
Type of polarization signal.

The one type of polarized signal of the signal of the one frequency band and the one type of polarized signal of the signal of the other frequency band are connected to a first low noise amplifier and a second low noise amplifier of the converter circuit. 1 bandpass filter, 1st mixer and 1st
The signal is converted using an offset ring filter.

The other type of polarized signal of the one frequency band signal and the other type of polarized signal of the other frequency band signal are the second low noise amplifier of this converter circuit. , A second band-pass filter, a second mixer, and a second offset ring filter.

The first low-noise amplifier receives one type of polarization signal and amplifies it with low noise. The first band-pass filter removes an image frequency band signal from one type of polarization signal and outputs the signal to the first mixer.

Then, the first mixer is connected to the first mixer.
And a local oscillation signal transmitted from the first or second local oscillator via the distributor and the first offset ring filter to output an IF signal. I do.

The second low-noise amplifier receives the other kind of polarized signal and amplifies it with low noise. The second band-pass filter removes an image frequency band signal from the other type of polarization signal and outputs the same to the second mixer.

Then, the second mixer is connected to the second mixer.
And a local oscillation signal transmitted from the first or second local oscillator via the distributor and the second offset ring filter to output an IF signal. I do.

According to the present invention, the first mixer converts one polarization signal of the signals in both the one and the other frequency bands, and the second mixer converts the signals of both the one and the other frequencies. The other polarization signal of the band signal is converted. That is, according to the present invention, the first and second mixers have a function of converting a signal in one frequency band and a function of converting a signal in the other frequency band.
Therefore, according to the present invention, the number of mixers can be reduced by half as compared with the conventional example that requires two dedicated mixers for one frequency band and two dedicated mixers for the other frequency band. Therefore, cost can be reduced.

Further, as described above, since the number of mixers can be reduced by half as compared with the conventional one, according to the present invention, one low noise amplifier can correspond to one mixer. Therefore, there is no need to distribute the signal from the low noise amplifier to a plurality of mixers. Therefore, according to the present invention, it is possible to input a signal having the same strength as the conventional one to the mixer by using the low-noise amplifier having a smaller number of amplification stages than the conventional example.

Further, since the number of mixers can be reduced by half as compared with the conventional case, the number of amplifiers and switches which need to be connected to the output terminal of the mixer can be reduced by half. Therefore, the number of parts can be reduced, and downsizing and cost reduction can be realized.

According to the first aspect of the present invention, the first and second offset ring filters block RF signals (high-frequency signals) from the first and second mixers. Therefore, the rejection characteristics of the first and second offset ring filters and the input / output isolation characteristics of the first and second mixers are multiplied, and the isolation between one polarized signal and the other polarized signal is performed. The operation characteristics can be improved.

Further, since the first and second offset ring filters can be constituted by a microstrip pattern of a printed circuit board, components such as capacitors are not required. Therefore, the isolation characteristics do not depend on the constants and performance of components such as capacitors. Therefore, performance degradation due to variation in mass production is small, and as a result, the isolation characteristic (cross polarization separation degree characteristic) of both polarization signals is improved in both frequency bands.

According to a second aspect of the present invention, a buffer amplifier is connected between the first local oscillator, the second local oscillator, and the distributor. Therefore, the local oscillator power can be amplified by this buffer amplifier. Therefore, it is possible to design so as to give priority to the phase noise characteristic and the change (temperature drift) characteristic of the oscillation frequency with respect to temperature change at the expense of power among the various characteristics of the two local oscillators. Therefore, it is possible to improve various characteristics other than the local oscillator power and reduce the cost of the local oscillator. Therefore, a low-noise block downconverter circuit with excellent cost performance can be realized.

According to a third aspect of the present invention, there is provided a first band-pass filter connected to an output terminal of a first local oscillator and a second band-pass filter connected to an output terminal of a second local oscillator. And Therefore, it is possible to improve the impedance matching characteristics of the output as viewed from the local oscillator side. Therefore, the load fluctuation characteristics of the oscillator are also improved, and the oscillator can be operated in a state where the initial stability of the oscillation frequency, the temperature stability, the phase noise characteristics, and the like, which are the basic performances of the oscillator, are good. Since the first and second bandpass filters can be constituted by microstrip lines on a printed circuit board, by finely adjusting the length and width of the pattern (copper foil portion) on the printed circuit board and the distance between the patterns. And fine adjustment of the impedance to the oscillator. Therefore, the initial frequency of the oscillation frequency of the oscillator can be easily adjusted.

Therefore, according to the third aspect of the present invention, the low noise in which the fundamental characteristics of the oscillator such as the initial stability of the oscillation frequency, the temperature stability, the phase noise characteristic and the variation characteristic of the initial frequency of the oscillation frequency are greatly improved. A block down converter circuit can be provided.

Further, according to the invention of claim 4, a first stub element connected between the first output terminal of the distributor and the first offset ring filter, and a second stub element of the distributor are provided.
A second stub element connected between the output end and the second offset ring filter, and an RF input signal from the first and second offset ring filters, the first and second stub elements To trap. Further, the first and second stub elements also play a role of improving impedance matching with respect to the output power signal of the local oscillator. As a result, the degree of separation between one polarized signal and the other polarized signal can be further improved. Therefore, the isolation characteristics between one polarized signal and the other polarized signal can be greatly improved.

According to the fifth aspect of the present invention, since the first mixer and the second mixer are active mixers having a conversion gain, the conversion output can be increased.

[0046]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.

FIG. 2 shows a main part of an embodiment of the low noise block down converter circuit of the present invention. This embodiment includes two first low noise amplifiers 2a and 2b connected in series to an input terminal 1 and two second low noise amplifiers 18a and 18b connected in series to an input terminal 17. I have. The first low-noise amplifiers 2a and 2b amplify the signal from the input terminal 1, and the second low-noise amplifier 18a
And 18b amplify the signal from input terminal 17. The input terminal 1 receives a horizontal polarization signal or a right-handed polarization signal, and the input terminal 17 receives a vertical polarization signal or a left-handed polarization signal. I have. Then, the first low noise amplifiers 2a and 2b
Each have one HEMT (high electron mobility transistor). Each of the second low-noise amplifiers 18a and 18b has one HEMT. And the first
The low-noise amplifiers 2a and 2b are connected to a bias circuit 38. The bias circuit 38 supplies an optimum drain voltage (about 2 V) and a drain current (10 mA) to the HEMT of the first low noise amplifiers 2a and 2b. Further, the second low noise amplifier 18
a and 18b are connected to a bias circuit 35. This bias circuit 35 includes the second low noise amplifiers 18a and 1
8b has the optimal drain voltage for HEMT
(About 2 V) and a drain current (10 mA). The bias circuits 38 and 35 obtain a voltage of about 9 V from the positive power supply terminal 33 and about -2 from the negative power supply terminal 34.
V voltage is obtained.

The above-described embodiment includes a first band-pass filter 3 and a first HEMT mixer 4 connected in series to the first low-noise amplifiers 2a and 2b. Further, the above embodiment is different from the second low noise amplifier 18
a, a second bandpass filter 10 and a second HEMT mixer 9 connected in series to 18b.
The first band-pass filter 3 is a filter that removes an image by removing a signal in a predetermined band from the signals from the first low-noise amplifiers 2a and 2b. The second band-pass filter 10 includes: Second low noise amplifier 18a, 1
8b is a filter that removes a signal in a predetermined band from the signal from 8b and removes an image.

Further, the first HEMT mixer 4 has
An active mixer having a conversion gain, converts the signal from the first bandpass filter 3 into an IF signal and outputs the IF signal from an IF signal output terminal 20. A resistor 21 connected to a gate bias supply terminal 19 is connected to an input of the first HEMT mixer 4, and a capacitor 23 is connected between the gate bias supply terminal 19 and the ground GND. I have. In addition, the above HEM
The capacitors 27 and 24 are connected between the output terminal 20 of the T mixer 4 and the ground. This output terminal 20
Is connected to a portion connecting the first HEMT mixer 4 and the first ring filter 5.

Further, the second HEMT mixer 9
An active mixer having a conversion gain, converts the signal from the second bandpass filter 10 into an IF signal, and outputs the IF signal from an IF signal output terminal 31. The second H
The EMT mixer 9 has a resistor 39 connected to the gate bias supply terminal 32 connected thereto, and a capacitor 40 connected between the gate bias supply terminal 32 and the ground GND. Further, capacitors 36 and 28 are connected between the output terminal 31 of the HEMT mixer 9 and the ground. This output terminal 31 is connected to the second H
It is connected to a part connecting the EMT mixer 9 and the first ring filter 8.

On the other hand, the above embodiment is the first embodiment for FSS reception.
, And a second local oscillator 14 for BSS reception. The oscillation frequency of the first local oscillator 13 is 10.75 GHz, and the oscillation frequency of the second local oscillator 14 is 11.25 GHz. The first local oscillator 13 is connected to a band-pass filter 11 that allows the oscillation signal of the first local oscillator 13 to pass therethrough.
This band pass filter 11 is connected to the buffer amplifier 6. The band-pass filter 11 also plays a role in matching between the first local oscillator 13 and the buffer amplifier 6. The second local oscillator 14 is connected to a band-pass filter 14 that allows the oscillation signal of the second local oscillator 14 to pass therethrough. The band-pass filter 14 is connected to the buffer amplifier 6, Of the local oscillator 14 and the buffer amplifier 6. The local oscillator 13 is connected to the power supply terminal 1
5 supplies a supply voltage of 5 V, and the local oscillator 14 is supplied with a supply voltage of 5 V from a power supply terminal 16. Of the power supply terminals 15 and 16, a supply voltage of 5 V is applied to the power supply terminal connected to the local oscillator 13 or 14 corresponding to the band to be received.

The buffer amplifier 6 includes one HEMT.
And is connected to the Y-type distribution circuit 7. The stub element 25 and the stub element 26 are connected to the Y-type distribution circuit 7. The stub element 25 is connected to the first HEMT mixer 4 via the first ring filter 5. In addition, the stub element 26 is a second
HEMT mixer 9 via ring filter 8
It is connected to the.

The Y-type distribution circuit 7 receives the local oscillator power from the local oscillators 13 and 14 and distributes the same to the first and second HEMT mixers 4 and 9 equally. It plays a role in matching with the first and second HEMT mixers 4 and 9. Note that R is a resistor for the Y-type distribution circuit.

The stub elements 25 and 26 are formed of microstrip lines, and play a role as matching devices for improving the matching between the Y-type distributor 7 and the ring filters 5 and 6 in the local oscillator frequency band. I have. Further, the stub elements 25 and 26 also serve as traps for preventing RF input signals from the first and second HEMT mixers 4 and 9 from entering the Y-type distribution circuit 7.

FIG. 7 shows an enlarged pattern of the first ring filter 5. As shown in FIG. 7, the first ring filter 5 includes a ring portion 5B including an octagonal outer periphery and a quadrilateral inner periphery, and opposing portions 5A and 5C opposing each other with the ring portion 5B interposed therebetween. have. FIG. 8 shows frequency pass characteristics of the first ring filter 5 and the second ring filter 8. As shown in FIG. 8, the first and second
The ring filters 5 and 8 have an oscillation frequency of 10.75 GHz of the local oscillator 13 for the FSS band and an oscillation frequency 11.25 of the local oscillator 14 for the BSS band.
It has a peak of the pass characteristic of a frequency component substantially at the center of GHz. Then, the FSS band (11.70 GHz to 1
2.20GHz) and BSS band (12.20GHz ~
The pass characteristic of the frequency component (12.70 GHz) is lower by about 10 decibels than the peak.

That is, the first ring filter 5
The center value of the resonance frequency is shifted (offset) to an intermediate frequency between the oscillation frequency of the local oscillator 13 and the oscillation frequency of the local oscillator 14. This first
The ring filter 5 passes the signal from the local oscillator 13 toward the first HEMT mixer 4 while the IF signal (950 MHz) from the first HEMT mixer 4
z to 1450 MHz) and a horizontally polarized signal (11.7 GHz to 12.2 GHz) or a right-handed polarized wave reception signal (12.2 GHz to 12.7 GHz) are blocked without passing through the Y-type distribution circuit 7.

The center value of the resonance frequency of the second ring filter 8 is shifted (offset) to an intermediate frequency between the oscillation frequency of the local oscillator 13 and the oscillation frequency of the local oscillator 14. The second ring filter 8 allows the signal from the local oscillator 14 to pass through to the second HEMT mixer 9, while the IF signal and the vertical polarization signal or the left-hand polarization reception signal from the second HEMT mixer 9. To the Y-type distribution circuit 7
Block without passing through.

The circuit of this embodiment shown in FIG. 2 is realized by a printed circuit board including a board made of 0.8 mm thick Teflon material. The wiring of this printed circuit board is constituted by a microstrip line. The dimensions of this printed circuit board are about 70mm
This single printed circuit board includes all the circuits of this embodiment except for the two local oscillators 13 and 14 described above.

FIG. 1 shows a converter circuit including a main part M of the embodiment shown in FIG. As shown in FIG.
Output terminal 20 of first HEMT mixer 4 of main part M
Is connected to an IF preamplifier 51, and the second H
The output terminal 31 of the EMT mixer 9 has an IF preamplifier 5
2 are connected. The IF preamplifier 51
Is connected to a temperature compensation circuit 53, and the temperature compensation circuit 53 is connected to an IF amplifier 54. An output terminal 55 is connected to the IF amplifier 54.
A temperature compensating circuit 56 is connected to the IF preamplifier 52.
Is connected. An output terminal 58 is connected to the IF amplifier 57.

The power supply 60 supplies power to the low noise amplifiers 2a, 2b, 18a, 18b of the main part M. The power supply 60 supplies power to the 5V power supply 61,
Supplies power to the local oscillator 13 or 14 via the switch 62. The power supply 60 is connected to the buffer amplifier 6 of the main part M and the IF preamplifier 5.
1, 52, the IF amplifiers 54 and 57, and the comparator 6
2 is powered. The comparator 62 is connected to the output terminal 5
5 according to the voltage of the control signal input from
Has the role of switching.

A dual polarity dual band low noise block down converter circuit having the above configuration
(DPDB LNB circuit) has an input frequency of 11.7 GHz
~ 12.2 GHz FSS (Fixed Satellite)
e) When receiving signals from a (Service) satellite,
A voltage value of 9 V or more is supplied to the output terminal 55 shown in FIG.
The comparator 62 sets the switch 62 to the connection state shown in FIG. Then, the horizontal polarized signal having the frequency of 11.7 GHz to 12.2 GHz is input to the input terminal 1, and the vertical polarized signal having the frequency of 11.7 GHz to 12.2 GHz is input to the input terminal 17. The horizontally polarized signal is low-noise amplified by 20 to 24 dB by the first low-noise amplifiers 2 a and 2 b and input to the first band-pass filter 3. The first band-pass filter 3 removes a signal in a predetermined band from the input signal to remove an image, and then inputs the signal to the first HEMT mixer 4.

On the other hand, the local oscillator 13 for FSS reception receives power from the power supply terminal 15 and
A signal of 75 GHz is oscillated and output. This 10.75
The oscillation signal of GHz is input to the buffer amplifier 6 via the band pass filter 11, and the buffer amplifier 6
After being amplified by the first HEMT via the Y-type distribution circuit 7, the stub element 25, and the first ring filter 5,
Input to the mixer 4.

Then, the first HEMT mixer 4
Converts the horizontal polarization signal from the input terminal 1 into the FSS
10.75 GH from the local oscillator 13 for reception
950 MHz to 1450 MH using the z oscillation signal
It is converted to an IF (intermediate frequency) signal of z. Then, the IF signal is output from the IF output terminal 20. The IF signal output from the first HEMT mixer 4 is amplified by an IF preamplifier 51, input to a temperature compensating circuit 53 to be temperature-compensated, further input to an IF amplifier 54 and amplified, and then output to an output terminal. It is output from 55.

On the other hand, the vertically polarized signal input from the input terminal 17 is supplied to the second low noise amplifier 18a and the amplifier 18a.
b, the noise is reduced by 20 to 24 dB,
The signal is input to the second bandpass filter 10. This second
The band pass filter 10 removes an image by removing a signal of a predetermined band from the input signal and then inputs the signal to the second HEMT mixer 9.

On the other hand, the oscillation signal of 10.75 GHz oscillated by the local oscillator 13 for FSS reception is
The signal is input to the second HEMT mixer 9 via the band pass filter 11, the buffer amplifier 6, the Y-type distribution circuit 7, the stub element 26, and the second ring filter 8. Then, the second HEMT mixer 9 converts the vertically polarized signal from the input terminal 17 into the FSS receiving local oscillator 13.
Using the 10.75 GHz oscillating signal from
The signal is converted into an IF signal of 1 MHz to 1450 MHz and output from the IF output terminal 20. The IF signal output by the second HEMT mixer 9 is amplified by an IF preamplifier 52, input to a temperature compensating circuit 56 to be temperature-compensated, further input to an IF amplifier 57 and amplified, and then output to an output terminal. 58.

In this embodiment, a BSS (Broadcast) satellite service (Servic) having an input frequency of 12.2 GHz to 12.7 GHz is used.
e)) When receiving a satellite signal, a voltage value of 7 V or less is supplied to the output terminal 55 shown in FIG.
2 switches the switch 62 to the connection state shown in FIG.
Then, the power from the 5V power supply 61 is supplied to the input terminal 16 of the local oscillator 14 for receiving the BSS,
The local oscillator 14 for S reception oscillates to 11.2
An oscillation signal of 5 GHz is output. On the other hand, a right-handed polarized signal having a frequency of 12.2 GHz to 12.7 GHz is input to the input terminal 1, and a left-handed polarized signal having a frequency of 12.2 GHz to 12.7 GHz is input to the input terminal 17. The subsequent signal processing is based on the FS
This is similar to the case where a signal from the S satellite is received.

The first ring filter 5 of this embodiment
Is an offset ring filter, while allowing the signal of the oscillation frequency (10.75 GHz) of the local oscillator 13 to pass, the horizontal polarization signal (11.70 GHz to 12.20 GHz) and the right-hand polarization signal (12.20 GHz to 12.70 GHz) and IF signal (950 MHz to 145
0MHz) is blocked without passing. The second ring filter 8 is an offset ring filter that allows the oscillation frequency (11.25 GHz) of the local oscillator 14 to pass therethrough, while also allowing the vertical polarization signal (11.70 GHz to 12.20 GHz) and the left-hand polarization signal (12.20 GHz) to pass. GHz to 12.70 GHz) and IF signal (950 MHz
(1450 MHz) is blocked without passing.

According to the configuration of this embodiment, unlike the conventional example, both the FSS band polarization signal and the BSS band polarization signal can be converted by the HEMT mixers 4 and 9. Therefore, according to this embodiment, it is only necessary to provide a half of the four HEMT mixers required in the conventional example. Therefore, the number of expensive HEMT elements can be reduced, and the cost can be reduced. Further, according to the configuration of this embodiment, since the polarization signals from the low noise amplifiers 2 and 18 do not need to be distributed by the Y-type distributor, the number of amplification stages of the low noise amplifiers 2 and 18 is smaller than that of the conventional example. Can be reduced. Therefore, the number of HEMT elements used in the low-noise amplifier can be reduced, and the cost can be reduced. Further, according to the configuration of this embodiment, the number of HEMT mixers is reduced by half.
Therefore, the number of IF preamplifiers and the number of IF switches can also be reduced to half. Therefore, the number of parts can be reduced, and both miniaturization and cost reduction can be realized.

In other words, according to this embodiment, the first low noise amplifiers 2a and 2b and the second low noise amplifier 18
The desired overall gain and noise figure performance can be obtained by the a, 18b and the first and second HEMT mixers 4, 9. Therefore, the number of amplification stages of the low noise amplifier can be reduced as compared with the conventional example. Therefore, according to this embodiment, the number of HEMTs, which are expensive semiconductor elements, can be reduced and the cost can be reduced as compared with the conventional example. Also, by reducing the number of amplification stages of the low-noise amplifier, the size of the printed circuit board on which components are mounted can be reduced, so that the cost can be reduced and the size can be reduced.

The noise figure characteristics of the dual-polarity dual-band low-noise block downconverter of this embodiment are as follows: the performance and gain characteristics of the first low-noise amplifier 2 having a two-stage HEMT configuration; 2 and the noise characteristic of the first and second HEMT mixers 4 and 9 and the first and second bandpass filters for removing the image at the next stage. Therefore, according to this embodiment, good noise characteristics can be obtained.

The first offset ring filter 5
And the second offset ring filter 8 separates the RF signals of the horizontal polarization signal and the vertical polarization signal. Further, the first offset ring filter 5 and the second offset ring filter 8 provide RF signals of the right-handed polarization signal and the left-handed polarization signal.
Separate (high frequency) signals.

Therefore, according to this embodiment, the blocking characteristics of the RF signal by the first and second offset ring filters 5 and 8 and the input and output isolation characteristics of the first and second HEMT mixers 4 and 9 are provided. And stub elements 25 and 26
The synergistic action with the RF input signal rejection characteristic of the above can improve the isolation characteristic between the horizontal polarization signal and the vertical polarization signal and the isolation characteristic between the right-hand polarization signal and the left-hand polarization signal. it can.

The first and second ring filters 5,
8 can be constituted by a microstrip line circuit pattern of a printed circuit board, so that components such as capacitors are not required. Therefore, the isolation characteristics do not depend on the constants and performance of components such as capacitors. Therefore, the performance degradation due to the mass production variation is small, and the isolation characteristics between the horizontal polarization signal and the vertical polarization signal and the isolation characteristics between the right-hand polarization signal and the left-hand polarization signal can be improved. That is, the cross-polarization separation characteristic is changed to two frequency bands (FSS band (11.70 GHz to 12.20 G
Hz) and the BSS band (12.20 GHz to 12.70 GHz). Therefore, the degree of separation between the horizontally polarized signal and the vertically polarized signal can be improved, the degree of separation between the right-handed polarized signal and the left-handed polarized signal can be improved, and the variation in the degree of separation can be reduced. .

Further, since the first and second offset ring filters 5 and 8 are band-pass filters of a narrow band, the isolation characteristic between the horizontal polarization signal and the vertical polarization signal, and the right-hand polarization signal and the The isolation characteristics with the left-handed polarized signal are greatly improved, and a dual-polarity dual-band low-noise block downconverter circuit having an isolation characteristic of 27 dB or more can be realized.

More specifically, FIG. 9 shows the isolation characteristic between the horizontal polarization signal and the vertical polarization signal in the FSS band in this embodiment, and shows the isolation between the right-hand polarization signal and the left-hand polarization signal in the BSS band. FIG. 10 shows the relation characteristics. A characteristic curve H shown in FIG. 9 indicates a reception level of a horizontally polarized signal when a vertically polarized signal is being received. As shown by the characteristic curve H, the reception level of the horizontal polarization signal at the time of reception of the vertical polarization signal is a level at which the cross polarization separation becomes 30 dB or more. Further, as shown by the characteristic curve V, the reception level of the vertical polarization signal when the horizontal polarization signal is being received is a level at which the cross polarization separation is 30 dB or more. In other words, the signal not to be received is smaller than the normalized reception level by 30 dB or more, and the cross polarization separation degree of the non-received signal achieves the target value of 27 dB or more. Further, as shown in FIG. 10, a characteristic curve R indicating the reception level of the right-handed polarization signal when the left-handed polarization signal is being received, and a left-handed polarization signal when the right-handed polarization signal is being received. Are both small levels such that the degree of cross-polarization separation exceeds 30 decibels. That is, BS
Also in S reception, the target value of the cross polarization separation degree is 27
Resolutions in excess of dB could be achieved.

In this embodiment, the buffer amplifier 6 is connected between the first local oscillator 13, the second local oscillator 14, and the distributor 7. Therefore, the local oscillator power can be amplified by the buffer amplifier 6. Therefore, it is possible to design such that the phase noise characteristic and the change (temperature drift) characteristic with respect to the temperature change of the oscillation frequency are given priority at the expense of the power among the various characteristics of the two local oscillators 13 and 14. Therefore, various characteristics other than the local oscillator power can be improved and the local oscillators 13 and 1 can be improved.
4 can be reduced in cost. Therefore, a low noise block downconverter circuit with excellent cost performance can be realized.

In this embodiment, the first band-pass filter 11 connected to the output terminal of the first local oscillator 13 and the second band-pass filter connected to the output terminal of the second local oscillator 14 And a filter 12. Therefore, it is possible to improve the output impedance matching characteristics as viewed from the local oscillator side. Therefore, the load fluctuation characteristics for the oscillators 13 and 14 are also improved, and the oscillators 13 and 14 can be operated in a state where the initial stability of the oscillation frequency, the temperature stability, and the phase noise characteristics, which are the basic performances of the oscillators, are good. The first and second band pass filters 11,
12 can be constituted by a microstrip line on a printed circuit board. By finely adjusting the length and width of the pattern (copper foil portion) on the printed circuit board and the distance between the patterns, the impedance of the oscillators 13 and 14 can be finely adjusted. Adjustments are possible. Therefore, the initial frequency adjustment of the oscillation frequencies of the oscillators 13 and 14 becomes easy.

Therefore, according to this embodiment, the low noise block down device which greatly improves the oscillator characteristics such as the initial stability of the oscillation frequency, the temperature stability, the phase noise characteristics, and the variation characteristics of the initial frequency of the oscillation frequency, which are the basic characteristics of the oscillator. A converter circuit can be provided.

This embodiment is similar to the first embodiment of the distributor 7 described above.
A first stub element 25 connected between an output end and the first offset ring filter 5;
And the second offset ring filter 8
A second stub element 26 connected between
RF from the first and second offset ring filters 5 and 8
An input signal is trapped by the first and second stub elements 25 and. Further, the first and second stub elements 25, 26
Also plays a role of improving the impedance matching for the output power signals of the local oscillators 13 and 14. As a result, the degree of separation between one polarization signal (horizontal polarization signal, right-hand polarization signal) and the other polarization signal (vertical polarization signal, left-hand polarization signal) can be further improved. Therefore, the isolation characteristics between one polarized signal and the other polarized signal can be greatly improved.

Further, in this embodiment, since the first HEMT mixer 4 and the second HEMT mixer 9 are active mixers having a conversion gain, the first HEMT mixer 4 and the second HEMT mixer 9 are separated from each other by an isolation between one polarized signal and the other polarized signal. The operation characteristics can be improved.

It should be noted that the present invention relates to the US Ku band satellite (FSS band satellite and BSS
Band dual-polarity dual-band low-noise block-down converter circuit (DPD) for receiving arbitrary signals in two different frequency bands and two different signals, not limited to reception from
B LNB circuit).

In the above embodiment, the first and second low-noise amplifiers 2 and 18 as amplifiers having HEMTs have amplifiers 2a and 2b and amplifiers 18a and 18b, respectively, and have two HEMTs. But only one HEM
It may be a low noise amplifier with T. Further, the low-noise amplifier may be composed of a semiconductor element other than the HEMT.

In the above embodiment, the first and second HEs are used.
The MT mixers 4 and 9 are used as HEMT mixers as HEMs.
Although the circuit configuration includes T, a capacitor, a resistor, etc., HE
It goes without saying that the MT mixer is not limited to the above configuration. Further, instead of the HEMT mixer, an active mixer constituted by a semiconductor element other than the HEMT having a conversion gain may be provided.

Further, in the above-described embodiment, the band-pass filters 11 and 12 shown in FIG. 2, the buffer amplifier 6, and the stub elements 25 and 26 are provided. However, as shown in FIG. The converter circuit may not include the buffer circuit 12, the buffer amplifier 6, and the stub elements 25 and 26.

Further, as shown in FIG. 4, the converter circuit may not include the band-pass filters 11 and 12 and the stub elements 25 and 26.

Further, as shown in FIG. 5, a converter circuit without the buffer amplifier 6 and the stub elements 25 and 26 may be used.

As shown in FIG. 6, the converter circuit may not include the band-pass filters 11 and 12 and the buffer amplifier 6.

[0088]

As is clear from the above, the low-noise block down-converter circuit according to the first aspect of the present invention has the following features.
, A first band-pass filter receiving a signal from the first low-noise amplifier and outputting a signal in a predetermined band, and a signal in a predetermined band output from the first band-pass filter Mixer for converting the signal into an IF (intermediate frequency) signal and outputting the IF signal, a first offset ring filter connected to the first mixer, a second low-noise amplifier, and a second low-noise amplifier And a second band-pass filter for receiving a signal from the second band-pass filter and outputting a signal of a predetermined band; A mixer, a second offset ring filter connected to the second mixer, an input terminal, and first and second output terminals extending in two from the input terminal; Oscillates a signal of the first frequency The first output is connected to a first local oscillator and a second local oscillator that oscillates a signal of a second frequency, while the first output is connected to a first offset ring filter and the second output is connected to a second output. Is the second
And a distributor connected to the offset ring filter.

According to the present invention, the first mixer converts one polarization signal of the signals in both the one and the other frequency bands, and the second mixer performs the signal conversion on both the one and the other frequency bands. The other polarization signal of the signal is converted. That is,
According to the present invention, the first and second mixers have a function of converting a signal in one frequency band and a function of converting a signal in the other frequency band. Therefore,
According to the present invention, the number of mixers can be reduced by half as compared with the conventional example in which two dedicated mixers for one frequency band and two dedicated mixers for the other frequency band are required. Therefore, cost can be reduced.

Further, since the number of mixers can be reduced by half as compared with the prior art, according to the present invention, one mixer can correspond to one low noise amplifier. Therefore, there is no need to distribute the signal from the low noise amplifier to a plurality of mixers. Therefore, according to the present invention, it is possible to input a signal having the same strength as the conventional one to the mixer by using the low-noise amplifier having a smaller number of amplification stages than the conventional example.

Further, since the number of mixers can be halved as compared with the related art, the number of amplifiers and switches that need to be connected to the output terminal of the mixer can be halved. Therefore, the number of parts can be reduced, and downsizing and cost reduction can be realized.

According to the first aspect of the present invention, the first and second offset ring filters block RF signals (high-frequency signals) from the first and second mixers. Therefore, the rejection characteristics of the first and second offset ring filters and the input / output isolation characteristics of the first and second mixers are multiplied, and the isolation between one polarized signal and the other polarized signal is performed. The operation characteristics can be improved.

Since the first and second offset ring filters can be constituted by a microstrip pattern of a printed circuit board, components such as capacitors are not required. Therefore, the isolation characteristics do not depend on the constants and performance of components such as capacitors. Therefore, performance degradation due to variation in mass production is small, and as a result, the isolation characteristic (cross polarization separation degree characteristic) of both polarization signals is improved in both frequency bands.

According to a second aspect of the present invention, a buffer amplifier is connected between the first local oscillator, the second local oscillator, and the distributor. Therefore, the local oscillator power can be amplified by this buffer amplifier. Therefore, it is possible to design so as to give priority to the phase noise characteristic and the change (temperature drift) characteristic of the oscillation frequency with respect to temperature change at the expense of power among the various characteristics of the two local oscillators. Therefore, improvement of various characteristics other than local oscillator power,
The cost of the local oscillator can be reduced. Therefore, a low noise block downconverter circuit with excellent cost performance can be realized.

Further, the invention of claim 3 is characterized in that the first band-pass filter connected to the output terminal of the first local oscillator and the second band-pass filter connected to the output terminal of the second local oscillator And Therefore, it is possible to improve the output impedance matching characteristics as viewed from the local oscillator side. Therefore, the load variation characteristic of the oscillator is also improved, and the oscillator can be operated in a state where the initial stability of the oscillation frequency, the temperature stability, the phase noise characteristic, and the like, which are the basic performances of the oscillator, are good. Further, since the first and second bandpass filters can be constituted by microstrip lines on a printed board, the length and width of the pattern (copper foil portion) on the printed board and the distance between the patterns are finely adjusted. This allows fine adjustment of the impedance to the oscillator. Therefore, the initial frequency of the oscillation frequency of the oscillator can be easily adjusted.

Therefore, according to the third aspect of the present invention, the low noise in which the fundamental characteristics of the oscillator such as the initial stability of the oscillation frequency, the temperature stability, the phase noise characteristic, and the variation characteristic of the initial frequency of the oscillation frequency are greatly improved. A block down converter circuit can be provided.

Further, according to the present invention, the first stub element connected between the first output terminal of the distributor and the first offset ring filter, the second output terminal of the distributor and the second stub element are connected to each other. A second stub element connected between the first and second offset ring filters, and traps the RF input signals from the first and second offset ring filters with the first and second stub elements. Further, the first and second stub elements also play a role of improving impedance matching with respect to the output power signal of the local oscillator. as a result,
The degree of separation between one polarized signal and the other polarized signal can be further improved. Therefore, the isolation characteristics between one polarized signal and the other polarized signal can be greatly improved.

Further, according to the invention of claim 5, since the first mixer and the second mixer are active mixers having a conversion gain, the isolation characteristic between one polarized signal and the other polarized signal is obtained. Can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a low noise block down converter circuit of the present invention.

FIG. 2 is a circuit diagram of a main part of the embodiment.

FIG. 3 is a circuit diagram of a modification of the embodiment.

FIG. 4 is a circuit diagram of another modified example of the embodiment.

FIG. 5 is a circuit diagram of another modified example of the embodiment.

FIG. 6 is a circuit diagram of another modified example of the embodiment.

FIG. 7 is a schematic configuration diagram of an offset ring filter of the embodiment.

FIG. 8 is a signal transmission characteristic diagram of the offset ring filter.

FIG. 9 is a characteristic diagram illustrating cross polarization separation at the time of FSS band reception in the above embodiment.

FIG. 10 is a characteristic diagram showing the cross polarization separation at the time of receiving the BSS band in the embodiment.

FIG. 11 is a block diagram showing a satellite broadcast receiving system.

FIG. 12 is a block diagram of a conventional dual polarity dual band low noise block down converter circuit.

[Explanation of symbols]

1: input terminal for horizontal polarized signal (or right-handed polarized signal)
2 1st low noise amplifier, 3 1st band pass filter, 4 1st HEMT mixer, 5 1st offset ring filter, 6 ... buffer amplifier, 7 ... Y type distributor, 8 ... 1st 2, an offset ring filter, 9 ... a second HEMT mixer, 10 ... a second bandpass filter,
11, 12: band pass filter, 13: first local oscillator, 14: second local oscillator, 17: input terminal of a vertically polarized signal (or left-handed polarized signal), 18 ...
2nd low noise amplifier, 15, 16 ... power supply terminals, 2
0, 31: IF output terminal of HEMT mixer, 25, 2
6 ... stub element, 35, 38 ... bias circuit, 19, 3
2 ... Gate bias supply terminal of HEMT mixer, 2
4, 28 ... matching capacitors, 22, 23, 27, 36, 3
7,40 ... noise reduction capacitor, 21,39 ... HEMT
Mixer series resistor for gate voltage supply, 30: gate voltage supply terminal of buffer amplifier, 29: drain voltage supply terminal of buffer amplifier, 33: positive power supply terminal for bias circuit of HEMT, 34 ... negative power supply for bias circuit of HEMT Supply terminal.

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-61-101133 (JP, A) JP-A-5-136619 (JP, A) JP-A-7-86979 (JP, A) JP-A 60-101 3213 (JP, A) JP-A-2-53306 (JP, A) JP-A-63-173406 (JP, A) JP-A-7-183732 (JP, A) (58) Fields investigated (Int. ⁷ , DB name) H03D ⁷ /00-9/06 H04B 1/16-1/26

Claims (6)

(57) [Claims] A first low-noise amplifier; a first band-pass filter receiving a signal from the first low-noise amplifier and outputting a signal in a predetermined band; and a first band-pass filter. A first signal that converts a signal of a predetermined band output from the IF into an IF (intermediate frequency) signal and outputs the signal.
, A first offset ring filter connected to the first mixer, a second low-noise amplifier, and a signal in a predetermined band received from the second low-noise amplifier. A second bandpass filter for outputting, a second mixer for converting a signal of a predetermined band output from the second bandpass filter into an IF signal and outputting the IF signal, and a second mixer connected to the second mixer. A second offset ring filter, having an input end and first and second output ends extending in two from the input end, wherein the input end oscillates a signal of a first frequency. A first local oscillator and the first local oscillator
While being connected to a second local oscillator that oscillates a signal of a second frequency different from the frequency of
An output end is connected to the first offset ring filter, and the second output end is provided with a distributor connected to the second offset ring filter. Wherein the offset ring filter according to (1) uses a frequency component intermediate between the first frequency and the second frequency as a peak of the pass characteristic. 2. The low noise block down converter circuit according to claim 1, wherein a buffer amplifier is connected between said first local oscillator, said second local oscillator, and said distributor. Oscillator circuit. 3. The low-noise block down-converter circuit according to claim 1, wherein the first band-pass filter is connected to an output terminal of the first local oscillator, and is connected to an output terminal of a second local oscillator. A local oscillator circuit comprising: a second bandpass filter. 4. The low-noise block down-converter circuit according to claim 1, wherein: a first stub element connected between a first output terminal of the distributor and the first offset ring filter; And a second stub element connected between the second output terminal of the filter and the second offset ring filter, wherein the RF input signals from the first and second offset ring filters are transmitted to the first and second offset ring filters. 2. A low-noise block down-converter circuit, wherein trapping is performed by two stub elements. 5. The low noise block down converter according to claim 1, wherein the first mixer and the second mixer are active mixers having a conversion gain. 6. The low-noise block down-converter circuit according to claim 1, wherein an IF (intermediate frequency) amplifier is connected to an output terminal of each of the first mixer and the second mixer. And both IF
A low-noise block-down circuit, wherein a temperature compensation circuit is connected to each of the amplifiers.