JP2006211265A - Semiconductor switching circuit and receiving system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor switching circuit capable of obtaining a damping characteristic of little distortion with respect to a large-amplitude received signal even if a control signal is in a transition region, and a receiving system using a semiconductor switch like this. <P>SOLUTION: This semiconductor switching circuit is a circuit wherein a voltage Vgs between a gate and a source of its field effect element becomes constant irrespective of the magnitude of the amplitude of a received signal inputted to an input terminal. Namely, the voltage of the gate terminal of the field effect element is made to follow a variation in the received signal so as to prevent the voltage Vgs between the gate and the source of the field effect element from being dependent on the magnitude of the amplitude of the received signal. Moreover, the receiving system is a system equipped with a semiconductor switching circuit like this. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a semiconductor switch circuit for temporarily attenuating a signal from a receiving circuit and a receiving apparatus using the semiconductor switch circuit.

  In order to measure the distance to the object, a pulse that transmits a pulse-modulated transmission pulse wave, receives a reception signal reflected from the object, and calculates the distance to the object from the round-trip time to the object Radar equipment is used. In the pulse radar device, the round trip distance to the object is obtained by integrating the speed of light in the time from when the transmission signal is transmitted until the reflected wave from the object is received. The time until the reflected wave from the object is received is measured, and the distance to the object is calculated.

  On the other hand, in the pulse radar device, if the transmission signal from the pulse generation circuit leaks to the reception circuit, the reception signal generated by the leak will be detected as the reception signal from the object, so if there is an object by mistake I will judge.

  In order to reduce such a leak, a technique has been proposed in which the reception signal from the receiving circuit is temporarily attenuated to remove the influence of the leak pulse (see, for example, Patent Document 1).

  In the mobile communication field, a semiconductor switch circuit is required for switching between transmission and reception of an antenna of a mobile phone. As such a semiconductor switch circuit, for example, a semiconductor switch circuit as described in Patent Document 2 has been proposed.

  An example of a semiconductor switch circuit that outputs an attenuated signal obtained by temporarily attenuating such a received signal is shown in FIG. In FIG. 1, 81 is an input terminal, 82 is a control terminal, 83 is an output terminal, 91 is a field effect element, S is a source of the field effect element, D is a drain of the field effect element, and G is a gate of the field effect element. .

  A received signal is input to the input terminal 81 and output from the output terminal 83. When the received signal from the input terminal 81 to the output terminal 83 is temporarily attenuated, a control signal for temporarily attenuating the received signal is input to the control terminal 82. The received signal is temporarily attenuated by the control signal from the control terminal, and is output from the output terminal as an attenuated signal.

Japanese Utility Model Laid-Open No. 5-11080. JP-A-7-86899.

  Examples of input signals, control signals, and attenuation signals are shown in FIG. FIG. 2A is an example of a received signal from a receiving circuit of a pulse radar device, for example. Depending on the phase state at the time of mixing, a signal appears on the plus side or the minus side. The reception signal corresponding to the first pulse is generated when the transmission signal from the pulse generation circuit leaks to the reception circuit, and the reception signal corresponding to the subsequent pulse is generated by reflection from the object.

  It is necessary to attenuate the received signal generated by the leak so as not to be detected as a received signal from the object. The received signal in FIG. 2 (1) is input to the input terminal 81 in FIG. 1, and the received signal generated by the leak is attenuated by the control signal as shown in FIG. 2 (2). Here, if the control signal is a square wave, the harmonic component of the square wave is added to the received signal, which causes erroneous detection. Therefore, a control signal as shown in FIG. 2 (2) with less harmonic components is used.

  The inventor inputs the reception signal shown in FIG. 2 (1) to the input terminal 81 of the semiconductor switch circuit shown in FIG. 1, and the control signal shown in FIG. 2 (2) to the control terminal 82 of the semiconductor switch circuit shown in FIG. 1 is input, the attenuation signal output to the output terminal 83 of the semiconductor switch circuit shown in FIG. 1 has a waveform as shown in FIG. When the control signal rises or falls, the attenuation rate is worse on the minus side than the plus side of the received signal, and it is erroneously detected as reflection from the object. Depending on the phase state at the time of mixing, the positive side or the negative side is not determined, and uncertainty remains in the detection result.

  The inventor examined this cause and found out that the difference in the voltage between the gate and the source of the field effect element was increased due to the difference in the polarity of the received signal. That is, the difference in the gate-source voltage of the field effect element increases depending on the amplitude of the received signal, which affects the transfer characteristics of the field effect element. 3 and 4 are diagrams for explaining the voltage relationship between the terminals of the field effect element. The same reference numerals as those in FIG. 1 represent the same meaning. As shown in FIG. 3, for example, when Vin = −0.2V is input to the input terminal 81 and Vctl = −0.5V is input to the control terminal 82, the gate-source voltage is Vgs = −0.3V. Become. However, as shown in FIG. 4, for example, when Vin = + 0.2V is input to the input terminal 81 and Vctl = −0.5V is input to the control terminal 82, the gate-source voltage is Vgs = −0.7V. It becomes. In this way, when a signal with a large amplitude is input to the input terminal, the gate-source voltage Vgs of the field effect element 91 is greatly different, and this difference causes a difference in the attenuation rate between the plus side and the minus side of the received signal. It was clarified that.

  This characteristic is expressed as input / output characteristics as shown in FIG. FIG. 5 shows the reception signal Vin input to the source terminal of the field effect element on the horizontal axis and the attenuation signal Vout output from the drain of the field effect element on the vertical axis using the control signal as a parameter. In FIG. 5, when the control signal is in a passing state, the received signal Vin and the attenuated signal Vout are substantially equal, and when the control signal is in an attenuated state, the signal is attenuated regardless of the magnitude of the received signal Vin. The signal Vout becomes almost zero. However, when the control signal is in the transition region, the received signal Vin on the plus side is substantially attenuated, whereas the received signal Vin on the minus side is not attenuated and the attenuated signal Vout is substantially equal to the received signal Vin. Become. With such input / output characteristics, when the control signal is in the transition region, the attenuation signal is greatly distorted.

  In addition, the control signal shown in FIG. 2 (2) is extended to the time position near the head of the pulse corresponding to the reflected wave from the object, and the reflected wave signal from the object at a close distance is also obtained. In the case of attenuation, when the control signal is in a transition state, the signal level varies depending on the polarity of the received signal as in the case described above. In order to correctly identify the received signal regardless of the polarity, the threshold value for identifying the pulse of the received signal must be set separately depending on the polarity, which causes a problem that the setting becomes complicated.

  In order to solve such problems, it is an object of the present invention to provide a semiconductor switch circuit that can obtain an attenuation characteristic with little distortion with respect to a large amplitude received signal even when the control signal is in a transition region. And Another object of the present invention is to provide a receiving apparatus using such a semiconductor switch.

  In order to achieve the above object, the inventor has created a semiconductor switch circuit in which the gate-source voltage Vgs of the field effect element is constant regardless of the amplitude of the received signal input to the input terminal. That is, the voltage of the gate terminal of the field effect element is made to follow the fluctuation of the received signal so that the gate-source voltage Vgs of the field effect element does not depend on the amplitude of the received signal.

  The principle diagram is shown in FIGS. 6 or 7, 11 is an input terminal, 12 is a control terminal, 13 is an output terminal, 21 is a field effect element, 36 is a resistor, S is a source of the field effect element, D is a drain of the field effect element, G is Represents the gate of a field effect element.

  In FIG. 6, the reception signal Vin = −0.2 V is input to the input terminal 11, and the control signal Vctl = −0.5 V is input to the control terminal 12. When the circuit configuration is such that Vin is applied from the source to the gate of the field effect element, the gate voltage becomes Vg = −0.7V, and the gate-source voltage of the field effect element at this time is Vgs = −0.7V + 0.2V. = −0.5V.

  In FIG. 7, the reception signal Vin = + 0.2 V is input to the input terminal 11, and the control signal Vctl = −0.5 V is input to the control terminal 12. When the circuit configuration is such that Vin is applied from the source to the gate of the field effect element, the gate voltage becomes Vg = −0.3 V, and the gate-source voltage of the field effect element at this time is Vgs = −0.3 V−0. .2V = -0.5V.

  From this result, it can be seen that Vgs of the field effect element can be constant regardless of the polarity of the reception signal input to the input terminal 11. That is, even if the received signal input to the input terminal 11 has a large amplitude, an attenuated signal with little distortion can be obtained. However, when a control signal input from the control terminal 12 is applied to the source, the control signal is output to the output terminal 83 via the source-drain of the field effect element, and as a result, the switch circuit does not operate. Signal transmission from the gate to the source must be blocked.

  Therefore, in the first invention of the present application, the received signal is transmitted from the source of the field effect element to the gate, and the control signal is not transmitted from the gate of the field effect element to the source. Are connected with an isolator.

  Specifically, the first invention of the present application includes a first field effect element having a source connected to an input terminal, a gate connected to a control terminal, and a drain connected to an output terminal, and the source of the first field effect element. Is connected between the gate and the gate of the first field effect element, a signal is transmitted from the source to the gate, and a signal is not transmitted from the gate to the source of the first field effect element. And a semiconductor switch circuit.

  According to the first invention of the present application, since the reception signal input to the input terminal is applied to the source and gate of the first field effect element, even when the control signal is in the transition region, It is possible to provide a semiconductor switch circuit capable of obtaining an attenuation characteristic with little distortion.

  The second invention of the present application provides the first field effect element so that the reception signal is transmitted from the source to the gate of the first field effect element and the control signal is not transmitted from the gate to the source of the first field effect element. The source and the gate of each are connected by a second field effect element.

  Specifically, the second invention of the present application includes a first field effect element in which a source is connected to an input terminal, a gate is connected to a control terminal, and a drain is connected to an output terminal, and the source is the first field effect element. A semiconductor switch circuit comprising: a second field effect element having a gate connected to the source of the first field effect element.

  According to the second invention of the present application, since the reception signal input to the input terminal is applied to the source and gate of the first field effect element, even when the control signal is in the transition region, It is possible to provide a semiconductor switch circuit capable of obtaining an attenuation characteristic with little distortion.

  In the third invention of the present application, similarly to the second invention of the present application, the received signal is transmitted from the source to the gate of the third field effect element, and the control signal is not transmitted from the gate to the source of the third field effect element. The fourth field effect element is connected between the source and gate of the third field effect element.

  Specifically, the third invention of the present application includes a third field effect element having a source connected to the input terminal and a drain connected to the output terminal, a source connected to the gate of the third field effect element, and a gate connected to the gate. And a fourth field effect element having a drain connected to a control terminal at the source of the third field effect element.

  According to the third invention of the present application, since the reception signal input to the input terminal is applied to the source and gate of the third field effect element, even when the control signal is in the transition region, It is possible to provide a semiconductor switch circuit capable of obtaining an attenuation characteristic with little distortion.

  In the fourth invention of the present application, a receiving device that can temporarily attenuate the received signal from the receiving circuit is configured using any of the semiconductor switch circuits from the first invention of the present application to the third invention of the present application. .

  Specifically, the fourth invention of the present application relates to a receiving circuit that outputs a received signal, a control circuit that generates a control signal that temporarily attenuates the received signal from the receiving circuit, and a received signal from the receiving circuit. A switch circuit that outputs an attenuated signal temporarily attenuated by a control signal from the control circuit, wherein the switch circuit is any one of the semiconductor switch circuits according to claim 1, A reception signal is input to the input terminal of the semiconductor switch circuit, the control signal is input to the control terminal of the semiconductor switch circuit, and the attenuation signal is output from the output terminal of the semiconductor switch circuit. It is a receiver.

  According to the fourth aspect of the present invention, even if the amplitude of the received signal from the receiving circuit is large, the received signal can be temporarily attenuated by the control signal from the control circuit, and an attenuated signal with less distortion can be output.

  According to the present invention, it is possible to realize a semiconductor switch circuit that can obtain an attenuation characteristic with less distortion with respect to a large amplitude received signal even when the control signal is in the transition region. Furthermore, a receiving apparatus using such a semiconductor switch circuit can also be realized.

  Embodiments of the present invention will be described below with reference to the drawings. However, the present invention is not limited to the following embodiments.

FIG. 8 is a block diagram illustrating an embodiment of a semiconductor switch circuit according to the present invention.
In FIG. 8, 10 is a semiconductor switch circuit, 11 is an input terminal, 12 is a control terminal, 13 is an output terminal, 21 is a first field effect element, 25 is an isolator, 36 is a resistor, and S is a first field effect element. , D represents the drain of the first field effect element, and G represents the gate of the first field effect element.

  The semiconductor switch circuit of this embodiment includes a first field effect element having a source connected to an input terminal, a gate connected to a control terminal via a resistor, and a drain connected to an output terminal, and the source of the first field effect element And an isolator in which a signal is transmitted from the source to the gate of the first field effect element and no signal is transmitted from the gate to the source of the first field effect element. is there.

  In FIG. 8, the isolator 25 transmits a signal from the source to the gate of the first field effect element 21, and does not transmit a signal from the gate to the source of the first field effect element 21. In the semiconductor switch circuit 10 configured as described above, the reception signal input to the input terminal 11 is applied to the source of the first field effect element 21. At the same time, the voltage is also applied to the gate of the first field effect element 21 through the isolator 25. The control signal input to the control terminal 12 is applied to the gate of the first field effect element 21 but is not transmitted to the source.

  Although the reception signal is applied to the source of the first field effect element 21, the reception signal and the control signal are added and applied to the gate of the first field effect element 21. Even if it is large, the gate-source voltage of the field effect element is constant, and it is possible to realize a semiconductor switch circuit that can obtain an attenuation characteristic with little distortion for a large amplitude received signal.

  FIG. 9 is a block diagram illustrating an embodiment of a semiconductor switch circuit according to the present invention. In FIG. 9, 10 is a semiconductor switch circuit, 11 is an input terminal, 12 is a control terminal, 13 is an output terminal, 21 is a first field effect element, 22 is a second field effect element, 31 is a coupling capacitor, 32 Is a DC voltage source for applying a bias voltage to the gate of the second field effect element 22, 33 and 34 are resistors for dividing the voltage of the DC voltage source 32, and 35 is a drain side of the second field effect element 22. A load resistance, 36 is a load resistance on the source side of the second field effect element 22, S is a source of the field effect element, D is a drain of the field effect element, and G is a gate of the field effect element.

  The semiconductor switch circuit of the present embodiment includes a first field effect element having a source connected to an input terminal, a gate connected to a control terminal via a resistor, and a drain connected to an output terminal, and a source connected to the first field effect element And a second field effect element having a gate connected to the source of the first field effect element.

  A zero potential control signal is applied to the control terminal 12 when the received signal is not attenuated, and a negative voltage control signal is applied when the received signal is attenuated. When a negative voltage is applied to the source or drain of the second field effect element 22, the gate potential of the second field effect element 22 fluctuates to the positive side, and if the value is large, a forward diode current flows. In order to prevent the forward diode current from flowing, the gate of the second field effect element 22 is DC-blocked by the coupling capacitor 31 and then the second electric field is generated by the DC voltage source 32, the resistor 33 and the resistor 34. The gate of the effect element 22 is set to a negative potential. Further, since the signal from the input terminal 11 is also applied to the gate of the first field effect element 21, the second field effect element 22 takes out the output by the source follower.

  In FIG. 9, the fluctuation of the gate potential of the second field effect element 22 changes the drain current of the second field effect element 22, but the fluctuation of the drain or source potential does not change the gate potential. A signal is transmitted from the source of the field effect element 21 to the gate, and no signal is transmitted from the gate of the first field effect element 21 to the source. In the semiconductor switch circuit 10 configured as described above, the reception signal input to the input terminal 11 is applied to the source of the first field effect element 21. At the same time, it is applied to the gate of the first field effect element 21 through the second field effect element 22. The control signal input to the control terminal 12 is applied to the gate of the first field effect element 21, but is not transmitted to the source of the first field effect element 21.

  Although the reception signal is applied to the source of the first field effect element 21, the reception signal and the control signal are added and applied to the gate of the first field effect element 21. Even if it is large, the gate-source voltage of the first field effect element 21 is constant, and it is possible to realize a semiconductor switch circuit that can obtain an attenuation characteristic with less distortion with respect to a large amplitude received signal.

  In FIG. 9, the gate of the field effect element 22 is set to a negative potential by the DC voltage source 32, the resistor 33, and the resistor 34. However, the gate is set to a positive potential according to the operating characteristics of the field effect element to be used. Also good.

  FIG. 10 is a block diagram illustrating an embodiment of a semiconductor switch circuit according to the present invention. In FIG. 10, 10 is a semiconductor switch circuit, 11 is an input terminal, 12 is a control terminal, 13 is an output terminal, 23 is a third field effect element, 24 is a fourth field effect element, 31 is a coupling capacitor, 37 Is a DC voltage source for applying a bias voltage to the gate of the fourth field effect element 24, 33 and 34 are resistors for dividing the voltage of the DC voltage source 37, and 35 is a source side of the fourth field effect element 24. The load resistance, 36 is the load resistance on the drain side of the fourth field effect element 24, S is the source of the field effect element, D is the drain of the field effect element, and G is the gate of the field effect element.

  In the semiconductor switch circuit of the present embodiment, the source is connected to the input terminal, the drain is connected to the output terminal, the source is connected to the gate of the third field effect element, and the gate is the third electric field. And a fourth field effect element having a drain connected to a control terminal at a source of the effect element.

  When the received signal is not attenuated, a positive potential control signal is applied to the control terminal 12, and when the received signal is attenuated, a zero voltage control signal is applied. In order to prevent a forward diode current from flowing to the gate of the fourth field effect element 24, the gate of the fourth field effect element 24 is DC-blocked by the coupling capacitor 31 and then the DC voltage source 37. The gate of the fourth field effect element 24 is set to a positive potential by the resistor 33 and the resistor 34. In addition, in order to apply the signal from the input terminal 11 to the gate of the third field effect element 23, the fourth field effect element 24 takes out the output by the source follower.

  In FIG. 10, the potential fluctuation of the gate of the fourth field effect element 24 changes the drain current of the fourth field effect element 24, but the fluctuation of the drain and source potentials of the fourth field effect element 24 is the fourth. Therefore, no signal is transmitted from the source of the third field effect element 23 to the gate, and no signal is transmitted from the gate of the third field effect element 23 to the source. In the semiconductor switch circuit 10 configured as described above, the reception signal input to the input terminal 11 is applied to the source of the third field effect element 23. At the same time, it is also applied to the gate of the third field effect element 23 through the fourth field effect element 24. The control signal input to the control terminal 12 is applied to the gate of the third field effect element 23, but is not transmitted to the source of the third field effect element 23.

  Although the reception signal is applied to the source of the third field effect element 23, the reception signal and the control signal are added and applied to the gate of the third field effect element 23. Even if it is large, the gate-source voltage of the third field effect element 23 is constant, and it is possible to realize a semiconductor switch circuit that can obtain an attenuation characteristic with little distortion with respect to a large amplitude received signal.

  In FIG. 10, the gate of the field effect element 24 is set to a positive potential by the DC voltage source 37, the resistor 33, and the resistor 34. However, the gate is set to a negative potential according to the operating characteristics of the field effect element used. Also good.

  FIG. 11 shows the simulation result of the input / output characteristics in the semiconductor switch circuit shown in FIG. FIG. 11 shows the received signal Vin input to the source terminal of the first field effect element on the horizontal axis and the attenuation signal Vout output from the drain of the first field effect element on the vertical axis using the control signal as a parameter. It is a representation. In FIG. 11, when the control signal is in a passing state, the received signal Vin and the attenuated signal Vout are substantially equal, and when the control signal is in an attenuated state, the signal is attenuated regardless of the magnitude of the received signal Vin. The signal Vout becomes almost zero. In addition, it can be seen that even when the control signal is in the transition region, the attenuation characteristics are substantially equal to both the plus-side received signal Vin and the minus-side received signal Vin. The simulation result of the input / output characteristics in the semiconductor switch circuit shown in FIG.

  Therefore, even when the control signal is in the transition region, it is possible to realize a semiconductor switch circuit that can obtain an attenuation characteristic with little distortion even for a large amplitude received signal.

  FIG. 12 shows an embodiment of a receiving device including the semiconductor switch circuit described above. FIG. 12 is an example including the semiconductor switch circuit 10 described in FIG. 12, the same reference numerals as those in FIG. 9 represent the same meaning. Reference numeral 40 denotes a receiving circuit that receives a signal via a wireless antenna, a metallic wire, an optical fiber, or the like. Reference numeral 50 denotes a control circuit that generates a control signal that temporarily attenuates the received signal from the receiving circuit 40.

  The receiving apparatus of this embodiment includes a receiving circuit that outputs a received signal, a control circuit that generates a control signal that temporarily attenuates the received signal from the receiving circuit, and a control circuit that controls the received signal from the receiving circuit. A switch circuit that outputs an attenuated signal temporarily attenuated by the signal, the switch circuit being any one of the semiconductor switch circuits described in FIGS. 8 to 10, wherein the received signal is an input terminal of the semiconductor switch circuit The control signal is input to the control terminal of the semiconductor switch circuit, and the attenuation signal is output from the output terminal of the semiconductor switch circuit.

  When it is desired to temporarily attenuate the reception signal from the reception circuit 40, the reception signal is attenuated by the control signal from the control circuit 50. When the semiconductor switch circuit 10 described with reference to FIG. 9 is used, an attenuated signal with little distortion can be obtained even for a large amplitude received signal.

  Although the example provided with the semiconductor switch circuit described in FIG. 9 has been described here, the same effect can be obtained even when the semiconductor switch circuit illustrated in FIG. 8 or the semiconductor switch circuit illustrated in FIG. 10 is provided. .

  As described above, according to the present invention, when a leak occurs in the pulse radar device, the received signal is temporarily attenuated or used for switching the transmission / reception of the antenna of the mobile phone. In contrast, a semiconductor switch circuit with less distortion and a receiving apparatus using the switch circuit can be realized.

  The semiconductor switch circuit or the receiving device of the present invention can be applied to a pulse radar device or a mobile phone.

It is a figure explaining the example of the semiconductor switch circuit which outputs the attenuation | damping signal which attenuate | damped the received signal temporarily. It is a figure explaining the example of an input signal, a control signal, and an attenuation signal. It is a figure explaining the voltage relationship of each terminal of the field effect element which is the conventional semiconductor switch. It is a figure explaining the voltage relationship of each terminal of the field effect element which is the conventional semiconductor switch. For a conventional semiconductor switch, the control signal is a parameter, the received signal Vin input to the source terminal of the field effect element is represented on the horizontal axis, and the attenuation signal Vout output from the drain of the field effect element is represented on the vertical axis. is there. It is a figure which shows the principle figure of the semiconductor switch circuit of this invention. It is a figure which shows the principle figure of the semiconductor switch circuit of this invention. It is a block diagram explaining embodiment of the semiconductor switch circuit based on this invention. It is a block diagram explaining embodiment of the semiconductor switch circuit based on this invention. It is a block diagram explaining embodiment of the semiconductor switch circuit based on this invention. It is a figure which shows the simulation result of the input-output characteristic in the semiconductor switch circuit of this invention. It is a figure which shows a receiver provided with the semiconductor switch circuit of this invention.

Explanation of symbols

10: Semiconductor switch circuit, 11: Input terminal, 12: Control terminal, 13: Output terminal, 21: Field effect element, 25: Isolator, 36: Resistance, 21: First field effect element, 22: Second electric field Effect element, 23: third field effect element, 24: fourth field effect element, 31: coupling capacitor, 32, 37: DC voltage source, 33, 34: voltage dividing resistor, 35, 36: load resistance, 40: receiving circuit, 50: control circuit, 81: input terminal, 82: control terminal, 83: output terminal, 91: field effect element

Claims (4)

A first field effect element having a source connected to the input terminal, a gate connected to the control terminal, and a drain connected to the output terminal;
A signal is transmitted from the source of the first field effect element to the gate, and the gate of the first field effect element is connected to the gate of the first field effect element. An isolator from which no signal is transmitted to the source;
A semiconductor switch circuit comprising: A first field effect element having a source connected to the input terminal, a gate connected to the control terminal, and a drain connected to the output terminal;
A second field effect element having a source connected to the gate of the first field effect element and a gate connected to the source of the first field effect element;
A semiconductor switch circuit comprising: A third field effect element having a source connected to the input terminal and a drain connected to the output terminal;
A fourth field effect element having a source connected to the gate of the third field effect element, a gate connected to the source of the third field effect element, and a drain connected to a control terminal;
A semiconductor switch circuit comprising: A receiving circuit for outputting a received signal;
A control circuit for generating a control signal for temporarily attenuating the received signal from the receiving circuit;
A switch circuit that outputs an attenuation signal obtained by temporarily attenuating a reception signal from the reception circuit with a control signal from the control circuit;
4. The semiconductor switch circuit according to claim 1, wherein the received signal is input to the input terminal of the semiconductor switch circuit, and the control signal is the control of the semiconductor switch circuit. 5. A receiving apparatus, wherein the attenuation signal is input to a terminal and output from the output terminal of the semiconductor switch circuit.

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