JP2006180237A - Gain control circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inexpensively constitute an attenuator having a wide variable attenuation range and improved linearity of an attenuation amount to a control voltage while excellently keeping distortion characteristics of a receiver. <P>SOLUTION: A region with a small attenuation amount (small in receiver input power) is attenuated by a high-frequency band PIN diode variable attenuator 1 with a simple constitution. A region with a large attenuation amount (large in receiver input power) is attenuated by the high-frequency band PIN diode variable attenuator 1, and also, attenuated by a π-type PIN diode variable attenuator 3 provided to an intermediate frequency stage and having relatively linear attenuation characteristics. Consequently, a control unit 4 controls so as to compensate the shortfall of an attenuation amount by the high-frequency band PIN diode variable attenuator 1 with an attenuation amount by the intermediate frequency stage π-type PIN diode variable attenuator 3. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a gain control circuit using a variable attenuator, and more particularly to a gain control system suitable for a high frequency signal receiver used in a microwave band, a millimeter wave band or the like having a PIN diode variable attenuator.

  As a function of the receiver, an automatic gain control (AGC) circuit is provided to prevent the output level from fluctuating due to a change in the input level due to fading or the like. The variable attenuator used in the automatic gain control circuit of the receiver has a small attenuation when the input level is low and an attenuation when the input level is high in order to keep the output level constant regardless of changes in the receiver input level. Is controlled to be large.

  As a variable attenuator in a high frequency band (several GHz to several tens GHz) such as a microwave band, a PIN diode variable attenuator is relatively often used. Characteristics required for the variable attenuator include linearity of the attenuation characteristic and a variable attenuation range. In addition, as a characteristic required for a receiver used for a large-capacity digital line in recent years, a low distortion characteristic of a receiving system is required. Since the distortion of the receiver is determined by the signal level input to the signal amplifier, in order to realize the low distortion characteristic, it is necessary to perform attenuation at a stage where the signal level at the previous stage is small.

FIG. 8 shows an example of a PIN diode variable attenuator (see Patent Document 1). A PIN diode D2 having the same characteristics as the PIN diode D1 is compared with the PIN diode D1 inserted in series in the high-frequency signal transmission path. Further, by supplying the control voltage V _cont via the operational amplifier circuit A1 having a series circuit of the resistor R2 as a feedback circuit, the linearity of the attenuation characteristic with respect to the control voltage V _cont is improved.

FIG. 9 shows another example of a variable attenuator using a PIN diode, in which a variable attenuating PIN diode D1 is inserted in parallel to the high-frequency signal transmission line. The PIN diode variable attenuator shown in FIG. 9 also has the same attenuation characteristic with respect to the control voltage V _{cont as the} PIN diode variable attenuator shown in FIG. In this example, since only one choke coil L1 needs to be inserted into the circuit that supplies the control voltage _Vcont , the cost is more advantageous than the PIN diode variable attenuator shown in FIG.

  The PIN diode variable attenuator shown in FIGS. 8 to 9 can obtain an attenuation characteristic in which the voltage attenuation ratio changes relatively linearly with respect to the control voltage with a simple configuration, but the variable attenuation range is not always sufficient. Instead, it is difficult to cope with receiver input power whose input level varies greatly with only one PIN diode variable attenuator. There is also a method of cascading a plurality of PIN diode variable attenuators. However, in the case of circuit elements operating in a high frequency band such as a microwave, the characteristics of distributed constants depending on the shape and the characteristics of attenuators due to parasitic capacitance are considered. In addition, since processing such as shielding is necessary, increasing the number of high-frequency elements is disadvantageous in terms of cost.

FIG. 10 shows still another example of a variable attenuator using a PIN diode (see Patent Document 2). PIN diodes D1 and D2 inserted in series in a high-frequency signal transmission line so as to have opposite polarities to each other. And PIN diodes D3 and D4 inserted in parallel to the high-frequency signal transmission path at both ends of the PIN diodes D1 and D2, respectively, constitute a π-type PIN diode variable attenuator, and PINs having the same characteristics as these PIN diodes by supplying the control voltage V _cont to the PIN diode D1~D4 a series circuit of a diode D5 and the resistor R2 via the operational amplifier A1 having a feedback circuit, the aim of improving linearity of the attenuation characteristic with respect to the control voltage V _cont Yes.

  FIG. 11 shows the control voltage vs. attenuation characteristics of the PIN diode variable attenuator shown in FIGS. 9 and 10, respectively. The solid line is the characteristic of the PIN diode variable attenuator of FIG. 9, and the dotted line is the PIN of FIG. The characteristic of a diode variable attenuator is shown.

  As is clear from the characteristics shown in FIG. 11, in the case of the variable attenuator using one PIN diode D1 shown in FIG. 8 or FIG. Although the linear attenuation is improved, the variable attenuation range is relatively narrow due to restrictions due to shape and cost, and in a region where the attenuation is large, the attenuation is saturated with respect to the control voltage and the linearity is deteriorated. .

  On the other hand, in the π-type PIN diode variable attenuator shown in FIG. 10, the variable attenuation range is relatively wide, and the control voltage vs. attenuation characteristic also changes almost linearly over the entire attenuation range. Therefore, if this π-type PIN diode variable attenuator is used as a variable attenuator in the high frequency band, the variable attenuation range and control voltage versus attenuation characteristics can be improved. However, in the π-type PIN diode variable attenuator, FIG. 8 or FIG. Compared to the variable attenuator composed of one PIN diode shown in the figure, the increase in the number of circuit elements operating in the high frequency band and the number of bias control terminals inevitably increases the size of the shape, and the distributed constant characteristics due to the shape It must be designed in consideration of the characteristics of the attenuator due to the parasitic capacitance. Furthermore, since the shape of the shield case becomes large, it is disadvantageous in terms of cost.

JP-A-62-53015 JP-A-9-214278

  On the other hand, in the case of a variable attenuator used in the intermediate frequency band, the signal level handled is higher than that of a high-frequency signal, but the operating frequency is low (for example, several hundred MHz or less), and an attenuator due to distributed constant characteristics or parasitic capacitance Therefore, it is easy to use the π-type PIN diode variable attenuator shown in FIG. 10 as a variable attenuator in the intermediate frequency band because the nonlinear distortion is relatively small. It is possible to achieve the desired variable attenuation range at a relatively low cost. However, as described above, the distortion of the receiver is determined by the level of the signal input to the signal amplifier. Therefore, if the signal level is controlled in the subsequent stage (intermediate frequency stage), deterioration of the distortion characteristic is inevitable. .

  FIG. 12 shows, as means for achieving the attenuation required for the attenuator, (1) When the PIN diode variable attenuator shown in FIG. 8 or FIG. When the π-type PIN diode variable attenuator shown in FIG. 10 is connected and attenuated only in the intermediate frequency band, and (3) the PIN diode variable attenuator and intermediate frequency band shown in FIG. 8 or FIG. 9 connected to the high frequency band 10 shows attenuation characteristics and receiver distortion characteristics when both are attenuated by the π-type PIN diode variable attenuator shown in FIG. In FIG. 12, the horizontal axis (control voltage) of the graph showing the attenuation characteristic is shared, but the actual control voltage is different in each case.

  When the attenuation is performed only by the high frequency band PIN diode variable attenuator (1) (solid line), the attenuation characteristic is good because the attenuation is performed in the high frequency band of the previous stage where the signal level is small, but the linearity of the attenuation characteristic is deteriorated. Further, when the required attenuation is not achieved, it is difficult to increase the variable attenuation range. When the attenuation is performed only by the intermediate frequency band PIN diode variable attenuator (dotted line) in (2), the attenuation is performed by the π-type PIN diode variable attenuator shown in FIG. The characteristics deteriorate.

  Further, when both the high frequency band PIN diode variable attenuator (3) and the intermediate frequency band PIN diode variable attenuator (3) are both attenuated (one-dot chain line), the linearity and distortion characteristics of the attenuation characteristics are the same as in the case of (1). The characteristics are almost intermediate in the case of (2), and the distortion characteristics are worse due to less attenuation by the high frequency band PIN diode.

  As described above, in the case of the conventional control method in the PIN diode variable attenuator, from the viewpoint of distortion, it is preferable to attenuate with a high frequency band PIN diode variable attenuator as much as possible, but the high frequency formed by a single PIN diode. In the band PIN diode variable attenuator, the linearity of the attenuation characteristic is deteriorated in a region where the attenuation is large. On the other hand, if the π-type PIN diode variable attenuator shown in FIG. 10 is used as the high frequency band PIN diode variable attenuator, the linearity of the attenuation characteristic is improved, but it is disadvantageous in terms of cost as described above.

  In view of the above problems in the PIN diode variable attenuator, an object of the present invention is to minimize the deterioration of the distortion characteristic and to make the attenuation characteristic substantially linear with respect to the control voltage in the required variable attenuation range. It is an object of the present invention to provide a means for realizing a variable attenuator capable of achieving the above at a relatively low cost.

  The present invention is configured by combining a high frequency band PIN diode variable attenuator and an intermediate frequency band PIN diode variable attenuator. At that time, in order to reduce the distortion of the receiver, gain control is performed mainly by a high frequency band PIN diode variable attenuator. For example, as shown in FIG. A PIN diode variable attenuator with a simple configuration is used, and the intermediate frequency band PIN diode variable attenuator has a relatively easy linear attenuation characteristic such as the π-type PIN diode variable attenuator shown in FIG. PIN diode variable attenuator that can be used.

  In a region where the attenuation is small (receiver input power is small), the high frequency band PIN diode variable attenuator is attenuated by a high frequency band PIN diode variable attenuator. In a region where the attenuation is large (receiver input power is large), a high frequency band PIN diode variable attenuator is used. And attenuating by the intermediate frequency band PIN diode variable attenuator, so that the shortage of attenuation by the high frequency band PIN diode variable attenuator is compensated by the attenuation by the intermediate frequency band PIN diode variable attenuator. It is characterized by.

  Specifically, the reception input level control circuit of the present invention is configured by a single PIN diode, and controls the level of the received input signal by changing the impedance of the PIN diode to control the attenuation amount. Compared to the down-converted intermediate frequency signal, which is composed of a frequency band PIN diode variable attenuator and a plurality of PIN diodes, and controlling the attenuation amount by changing the impedance of each of the plurality of PIN diodes. An intermediate frequency band PIN diode variable attenuator that performs level control having a linear attenuation characteristic, and the reception only for the high frequency band PIN diode variable attenuator when the receiver input power is below a predetermined level. A control signal for attenuating the input signal is supplied, and the receiver input power is In a range larger than the level, a control signal for attenuating the received input signal is supplied to the high frequency band PIN diode variable attenuator, and an insufficient amount of attenuation by the high frequency band PIN diode variable attenuator is reduced. And a control unit for supplying a control signal for attenuating the intermediate frequency signal to the intermediate frequency band PIN diode variable attenuator so as to compensate for a required attenuation.

  The high frequency band PIN diode variable attenuator in the present invention can be constituted by a single PIN diode connected in series or in parallel with the high frequency signal transmission path, and the control signal path is also connected to the single PIN diode. Thus, it is only necessary to supply the control unit via the choke coil via the high-frequency signal transmission line to which the PIN diode is connected, so that the high-frequency variable attenuator can be realized with a simple configuration.

  The intermediate frequency band PIN diode variable attenuator according to the present invention preferably includes first and second PIN diodes connected in series in opposite directions to the intermediate frequency transmission line, and the first and second PIN diodes connected in series. At both ends of the second PIN diode, a constant voltage is applied to the connection points of the third and fourth PIN diodes connected in parallel to the intermediate frequency transmission line, and the first PIN diode and the second PIN diode. A first choke coil connected for supply, a connection point between the first PIN diode and the third PIN diode, and a connection point between the second PIN diode and the fourth PIN diode; And second and third choke coils connected to supply a control signal from the control unit, and the first and second PIN diodes are controlled by the control signal. Wherein the impedance change direction of the diode third and impedance variation direction of the fourth PIN diode is controlled so as to be opposite to each other, [pi-type PIN diode variable attenuator can be used. Since the intermediate frequency band PIN diode variable attenuator has a low frequency, it can be realized relatively easily and at low cost even if its configuration is somewhat complicated.

  In the high frequency band PIN diode variable attenuator, the control unit according to the present invention can control the control voltage from the control start voltage according to the receiver input power level in a range where the receiver input power is below a predetermined level. A first control voltage that changes linearly and whose control voltage is fixed to the control voltage at the predetermined level in a range where the receiver input power is larger than the predetermined level, and the receiver input power is equal to or lower than the predetermined level. In the range, the control voltage is fixed to the control start voltage, and in the range where the receiver input power is larger than the predetermined level, the control voltage changes almost linearly from the control start voltage according to the receiver input power level. The control signal generated by adding the second control voltage to the control unit is supplied to the intermediate frequency band PIN diode variable attenuator Is against, supplies the control signal generated from only the second control voltage at the control unit.

  In addition, the control unit has a series circuit of a fifth PIN diode and a first resistor having the same characteristics as the PIN diode used in each variable attenuator as a feedback circuit, and the second resistor The control for supplying the high frequency band PIN diode variable attenuator by adding the first control voltage input through the second resistor and the second control voltage input through the third resistor. A series circuit of a first operational amplifier that generates and outputs a signal and a sixth PIN diode having the same characteristics as the PIN diode used in each of the variable attenuators and a fourth resistor is used as a feedback circuit. And a second operational amplifier that generates and outputs the control signal to be supplied to the intermediate frequency band PIN diode variable attenuator from the second control voltage input via the fifth resistor It can be configured to include a.

  According to the present invention, the linearity of the amount of attenuation with respect to the control voltage is improved as compared with the case where only the high frequency band PIN diode variable attenuator is used for attenuation, and the variable attenuation is performed at low cost while maintaining the distortion characteristics of the receiver. A wide range of attenuators can be constructed.

  FIG. 1 is a gain control circuit diagram of a receiver showing an embodiment of the present invention, which includes a high frequency attenuator circuit 1, a down converter 2, an intermediate frequency attenuator circuit 3, and a control unit 4. The receiver of this embodiment amplifies the high frequency amplifier circuit that amplifies the high frequency signal output from the high frequency attenuator circuit 1, the intermediate frequency signal output from the local oscillator, the down converter 2, or the intermediate frequency attenuator circuit 3. An intermediate frequency amplifier circuit and the like are also provided, but are omitted in the figure for clarity of the features of the present invention.

  The high-frequency attenuator circuit 1 has a high-frequency signal transmission path short-circuited by a PIN diode D1 that functions as a variable impedance element. A control signal from the control unit 4 is connected to the high-frequency signal transmission path and the PIN via a choke coil L1. It is supplied to the connection point of the diode D1. The intermediate frequency attenuator circuit 3 is configured as a π-type attenuator by PIN diodes D2 to D5, and a control signal from the control unit 4 passes through the choke coil L2 to the connection point of the PIN diodes D2 and D4. It is supplied to the connection point between the PIN diodes D3 and D5 via the choke coil L3. A constant voltage V0 for operating the π-type PIN diode variable attenuator is supplied to the connection point between the PIN diodes D2 and D3 via the choke coil L4.

In the present embodiment, two control voltages V _cont1 and V _cont2 are used. V _cont1 is connected to one input terminal of the operational amplifier A1 through the resistor R1 and used to control the high-frequency attenuator circuit 1. V _cont2 is connected to one input terminal of the operational amplifier A1 through the resistor R2 and to one input terminal of the operational amplifier A1 through the resistor R3, and is connected to the high frequency attenuator circuit 1 and the intermediate frequency attenuator circuit 3 respectively. Used to control both.

  A series circuit of a PIN diode D6 and a resistor R4 is connected to the feedback circuit of the operational amplifier A1, and a series circuit of a PIN diode D7 and a resistor R5 is connected to the feedback circuit of the operational amplifier A2. A logarithmic voltage-current conversion amplifier is formed. Therefore, the control voltage input to one input terminal of the operational amplifier A1 is supplied to the high frequency attenuator circuit 1 as a control signal subjected to inverse logarithmic voltage current conversion, and the control voltage input to one input terminal of the operational amplifier A2 is The intermediate frequency attenuator circuit 3 is output as a control signal subjected to inverse logarithmic voltage current conversion.

  FIG. 2 shows the total maximum attenuation when the high frequency attenuator circuit 1 and the intermediate frequency attenuator circuit 3 used in the gain control circuit of the receiver according to the present embodiment have the characteristics shown by the solid line and the dotted line in FIG. The attenuation characteristic and the distortion characteristic with respect to the control voltage when the amount is designed to be 35 dB are shown. 3 to 7 show operation characteristics of each control voltage, high frequency attenuator circuit, and intermediate frequency attenuator circuit when the total maximum attenuation is designed to be 35 dB in this embodiment. Yes.

  Next, the operation of this embodiment will be described. Here, as an example, when the high-frequency attenuator circuit 1 and the intermediate-frequency attenuator circuit 3 used in the present embodiment have the characteristics shown by the solid line and the dotted line in FIG. 11, the total maximum attenuation amount is 35 dB. The case of designing will be described with reference to FIGS.

  Since the variable attenuation range of the high frequency PIN diode variable attenuator 1 shown in FIG. 11 is about 27 dB, the variable range is insufficient by 8 dB. However, as described above, in order to widen the variable range using only the high-frequency variable attenuator 1, a large increase in cost is inevitable. Therefore, in the present embodiment, the required amount of attenuation (35 dB) is achieved by sharing the shortage with the intermediate frequency band PIN diode variable attenuator 3.

The high-frequency PIN diode variable attenuator 1 saturates with respect to the control voltage in a region where the attenuation is large (region where the control voltage is less than −3 V), as indicated by the solid line in FIG. However, the linearity is getting worse. Therefore, control as shown in FIG. 3 is performed by using the control voltages V _cont1 and V _cont2 , and the attenuation characteristic is designed so that the attenuation characteristic becomes the wavy line shown in FIG. That is, attenuation is performed only by the high frequency PIN diode variable attenuator 1 in the region where the attenuation is small, and attenuation is performed by both the high frequency PIN diode variable attenuator 1 and the intermediate frequency band PIN diode variable attenuator 3 in the region where the attenuation is large. By adding the intermediate frequency attenuation to the high frequency attenuation, the attenuation characteristic of the broken line is realized. In this case, the attenuation amount borne by the intermediate frequency attenuator circuit 3 is about 8 dB.

The intermediate frequency attenuator circuit 3 uses the π-type PIN diode variable attenuator shown in FIG. 10. When the graph (broken line) in FIG. 11 showing the control voltage vs. attenuation characteristic is seen, the attenuation is about 8 dB. At this time, the control voltage V _cont is about −1.1V. Therefore, in order to make the control current value when the control voltage V _cont2 shown in FIG. 3 is −3V equal to the control current value when the control voltage V _cont2 is −1.1V in FIG. 11, the value of the resistor R3 is changed to the value of the resistor R2. 3 / 1.1 = 2.7 times. Further, R1 = R2.

FIG. 5 shows the attenuation characteristics of the high-frequency attenuator circuit 1 when the control voltages V _cont1 and V _cont2 are swept as shown in FIG. The high-frequency attenuator circuit 1 is controlled by the control voltage V _{cont1 in a} region where the attenuation amount is small up to −3V, and after the control voltage V _cont1 becomes −3V, V _cont1 is fixed to −3V. In a region where the attenuation is larger than that, control is performed by changing the control voltage _Vcont2 from 0V to -3V. Since R1 = R2, the currents due to the control voltages V _cont1 and V _cont2 are evenly added, so the control voltage vs. attenuation characteristic of the high frequency attenuator circuit 1 is the same as the solid line attenuation characteristic shown in FIG.

FIG. 6 shows the attenuation characteristics of the intermediate frequency attenuator circuit 3 when the control voltages V _cont1 and V _cont2 are swept as shown in FIG. The intermediate frequency attenuator circuit 3 does not attenuate at all when the control voltage V _cont1 is operating between 0V and −3V. Then, when the control voltage V _cont2 operates, it attenuates. However, since R3 = 2.7 × R2, when the control voltage V _cont2 changes from _0V to −3V, an anti-logarithmic voltage-current conversion amplifier via the resistor R3. 11 is 2.7 times that of the current flowing through the anti-logarithmic voltage-current conversion amplifier via the resistor R2, and therefore, the horizontal axis of the graph in FIG. 11 is compared with the attenuation characteristic of the broken line shown in FIG. The attenuation characteristic is such that (range of 0V to -1.1V) is increased by 2.7 times.

FIG. 7 shows the total attenuation characteristics of the high-frequency attenuator circuit 1 and the intermediate-frequency attenuator circuit 3. The high-frequency attenuator circuit 1 and the intermediate-frequency attenuator circuit 3 are added together. The attenuation characteristic shown in FIG. 2 is obtained. Therefore, the linearity of the attenuation characteristic with respect to the control voltage is improved, and the required variable attenuation range is also satisfied. As for the distortion characteristic, since the attenuation is performed only by the high frequency attenuator circuit 1 in the attenuation region where the control voltage V _cont1 is 0V to -3V, the distortion characteristic is very good, and the control voltage V _cont1 is − Even in a large attenuation region where the control voltage V _cont2 operates in the range of _0V to −3V, which is fixed at 3V, most of the required attenuation amount is covered by the attenuation amount of the high-frequency attenuator circuit 1, so FIG. As shown, distortion is minimized.

  As described above, in this embodiment, a variable attenuator having a simple configuration composed of a single PIN diode is used as a high-frequency attenuator circuit, and reception is performed mainly by performing gain control (attenuation) with this high-frequency attenuator circuit. By reducing the distortion of the machine, the attenuation amount in the high frequency attenuator circuit can be linearized with a relatively easy attenuation characteristic such as a π-type PIN diode variable attenuator provided in the intermediate frequency stage. Since it is configured so that the required attenuation can be obtained in total by attenuating with the variable attenuator that can be used, the deterioration of the distortion characteristics is minimized, and the attenuation characteristics are set to the control voltage within the required variable attenuation range. On the other hand, a variable attenuator that can have a substantially linear characteristic can be realized at low cost.

It is a gain control circuit diagram of a receiver showing an embodiment of the present invention. It is a graph which shows the attenuation | damping characteristic with respect to the control voltage in this embodiment, and a distortion characteristic. It is a graph for demonstrating the operating characteristic in this embodiment. It is a graph for demonstrating the operating characteristic in this embodiment. It is a graph for demonstrating the operating characteristic in this embodiment. It is a graph for demonstrating the operating characteristic in this embodiment. It is a graph for demonstrating the operating characteristic in this embodiment. It is a circuit diagram which shows the prior art example of a PIN diode variable attenuator. It is a circuit diagram which shows the prior art example of a PIN diode variable attenuator. It is a circuit diagram which shows the prior art example of a PIN diode variable attenuator. 11 is a graph showing the control voltage versus attenuation characteristics of the conventional example shown in FIGS. 8 and 10 in comparison. It is a graph which compares and shows the control voltage with respect to the attenuation | damping characteristic and distortion characteristic of a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 High frequency attenuation circuit 2 Down converter 3 Intermediate frequency attenuation circuit 4 Control part D1-D7 PIN diode R1-R5, r1, r2 Resistor C1-C4 Capacitor L1-L3 Choke coil A1, A2 Operational amplifier RFin High-frequency signal input terminal IFout Intermediate Frequency signal output terminal V0 constant voltage V _cont1 , V _cont2 control voltage

Claims (6)

A high-frequency band PIN diode variable attenuator configured by a single PIN diode and performing level control on the received input signal by changing the impedance of the PIN diode and controlling the attenuation amount;
A level having a relatively linear attenuation characteristic with respect to the down-converted intermediate frequency signal, which is configured by a plurality of PIN diodes and controlling the attenuation amount by changing the impedance of each of the plurality of PIN diodes. An intermediate frequency band PIN diode variable attenuator for controlling;
In a range where the receiver input power is below a predetermined level, a control signal for attenuating the received input signal is supplied only to the high frequency band PIN diode variable attenuator, and the receiver input power is greater than the predetermined level. In the range, a control signal for attenuating the received input signal is supplied to the high frequency band PIN diode variable attenuator, and a required attenuation amount is compensated for an insufficient amount of attenuation by the high frequency band PIN diode variable attenuator. A control unit for supplying a control signal for attenuating the intermediate frequency signal to the intermediate frequency band PIN diode variable attenuator so that
A gain control circuit comprising:   The high frequency band PIN diode variable attenuator is constituted by the single PIN diode connected in series or in parallel with a high-frequency signal transmission line, and a control signal for the single PIN diode is transmitted from the control unit. The gain control circuit according to claim 1, wherein the gain control circuit is supplied via a high-frequency signal transmission line to which the pin diode is connected via a choke coil.   The intermediate frequency band PIN diode variable attenuator includes first and second PIN diodes connected in series in opposite directions to the intermediate frequency transmission line, and both ends of the first and second PIN diodes connected in series. The third and fourth PIN diodes connected in parallel to the intermediate frequency transmission line, respectively, and a connection point for supplying a constant voltage to the connection point of the first PIN diode and the second PIN diode. Control signals from the control unit are respectively connected to a connection point between the first choke coil, the first PIN diode and the third PIN diode, and a connection point between the second PIN diode and the fourth PIN diode. And a second choke coil connected to supply the first and second PIN diodes according to the control signal. The gain control circuit according to claim 1 or 2, characterized in that the impedance change direction of impedance changes direction and the third and fourth PIN diodes are controlled to be opposite to each other.   In the high frequency band PIN diode variable attenuator, the control voltage varies linearly from the control start voltage according to the receiver input power level in the range where the receiver input power is below a predetermined level, and the receiver input power is In the range larger than the predetermined level, the control voltage is fixed to the control voltage at the predetermined level. In the range where the receiver input power is lower than the predetermined level, the control voltage is the control start voltage. In the range in which the receiver input power is larger than the predetermined level, the control unit supplies a second control voltage that linearly changes from the control start voltage according to the receiver input power level. The control signal generated by the addition is supplied, and the intermediate frequency band PIN diode variable attenuator is supplied to the second control power by the control unit. The gain control circuit according to claim 1, wherein the control signal generated from only is characterized in that it is supplied.   The control unit has a series circuit of a fifth PIN diode having the same characteristics as the PIN diode used in each variable attenuator and a first resistor as a feedback circuit, and the second resistor The control for supplying the high frequency band PIN diode variable attenuator by adding the first control voltage input through the second resistor and the second control voltage input through the third resistor. A series circuit of a first operational amplifier that generates and outputs a signal and a sixth PIN diode having the same characteristics as the PIN diode used in each of the variable attenuators and a fourth resistor is used as a feedback circuit. And a second operational amplifier that generates and outputs the control signal to be supplied to the intermediate frequency band PIN diode variable attenuator from the second control voltage input via the fifth resistor The gain control circuit according to claim 4, characterized in that it comprises.   A high-frequency signal receiver comprising the gain control circuit according to claim 1.

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