| 摘要 |
PROBLEM TO BE SOLVED: To set a time constant of a smoothing circuit which carries out smoothing of control voltage of a gain control circuit to a value according to a frequency of a receiving signal. SOLUTION: The circuit switches on a desired switch out of switches SW1 to SW4 based on a frequency of received signals. For example, if the frequency is high, a number of switches to be turned on is made small, parallel capacitance becomes small, and the time constant becomes small. If the frequency of the receiving signal is low, a number of switches to be turned on is made large, the parallel capacitance becomes large, and the time constant becomes large. COPYRIGHT: (C)2008,JPO&INPIT
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