| 摘要 |
PURPOSE:To reduce the stray-in of a signal and deterioration of characteristics, by equipping a receiving circuit with a switch part which has the function of intercepting or passing the output signal of a variable gain amplification part, and a means for controlling a gain in response to the output of said switch part. CONSTITUTION:A receiving filter consists of the network composed of a resistor and accumulators 46-48, and an operational amplifier 43. When the control signal on a control signal line C is at a high level, an analog switch 42 is turned on and no signal appears at the output of the operational amplifier 43; when the control signal is at a low level, the analog switch 42 is turned off and a receiving filter output signal is sent out from the output of the operational amplifier 43. This output signal is supplied to a variable gain amplifier 44 through a variable gain amplifier control circuit 45. |
