Patent ID: 7411456

Claim:
An AGC circuit comprising: a variable gain amplifier circuit having a gain controlled with a gain control signal; a rectifier circuit for rectifying an output signal of the variable gain amplifier circuit; a voltage comparator for comparing a rectified signal from the rectifier circuit with a threshold voltage; an up/down counter that switches between up-counting and down-counting according to an output voltage of the voltage comparator; and a D/A converter circuit for outputting a voltage corresponding to a count value of the up/down counter, 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-counting is performed the up/down counter increments the count value in accordance with the first clock signal and when the down-counting is performed the up/down counter decrements the count value in accordance with the second clock signal, and the gain control signal and the threshold voltage correspond to the voltage output from the D/A converter circuit.