Patent ID: 6977550

Claim:
An AGC circuit comprising: a variable gain amplifier circuit that gain controls, in accordance with a gain control signal, an input signal to produce a gain controlled output signal; a rectification circuit that rectifies the gain controlled output signal to produce a rectified signal; a voltage comparator that compares the rectified signal with a preset voltage to produce a comparator output voltage; an up/down counter that switches, in accordance with the comparator output voltage, between an up-count operation and a down-count operation to produce a count value; and a D/A conversion circuit that outputs an analog voltage corresponding to the count value, wherein: the count value is produced in accordance with first and second clock signals, provided respectively to first and second input terminals of the up/down counter, such that: when the up-count operation is performed, the up/down counter increments the count value in accordance with the first clock signal; and when the down-count operation is performed, the up/down counter decrements the count value in accordance with the second clock signal, and the gain control signal provided to the variable gain amplifier circuit corresponds to the analog voltage output from the D/A conversion circuit.