| 摘要 |
PROBLEM TO BE SOLVED: To provide a muting circuit with little scatter of circuit characteristics by making a consumption current small. SOLUTION: In this muting circuit 10 for controlling an output level in accordance with the magnitude of voltage of a received signal, an operational amplifier 35 amplifies the received signal. A plurality of resistors 34 are serially connected, wherein one end is connected to a negative input port of the operational amplifier 35 and the other end is connected to an output port of the operational amplifier 35. An A/D converter 31 converts a signal representing received signal intensity from an analog signal to a digital signal. A digital control part 32 compares the magnitude of the signal converted into the digital signal by the A/D converter 31 with a prescribed set point to thereby set the number of resistors relating to the gain of the operational amplifier 35 in the plurality of resistors 34. COPYRIGHT: (C)2005,JPO&NCIPI
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