| 摘要 |
In an automatic gain control (AGC) circuit based on a peak detection system having two filters, a voltage comparator selects one of two voltages and compares the selected voltage with a detection signal output from a wave detector. A second AGC filter selects a cut-off frequency based on the result of comparison of the voltage comparator and supplies a signal resulting from low-pass filtering, based on the selected cut-off frequency, to a voltage-controlled amplifier as a control voltage. When a highly modulated signal is abruptly input, selection of the cut-off frequency of the second AGC filter occurs.
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