AGC CIRCUIT

摘要

Provided is an AGC circuit, which does not use an external capacity in the least so that it has a very low offset voltage and can be easily integrated. The AGC circuit comprises a variable gain amplifier circuit (GCA1) having a gain controlled by a gain control signal and having an output DC offset controlled by an offset compensation signal, an A/D conversion circuit (AD1) for A/D-converting the output signal of the variable gain amplifier circuit (GCA1), a level detecting circuit (Det1) for detecting the peak of the output signal of the A/D conversion circuit (AD1) thereby to detect the amplification level, a gain control circuit (Gctrl1) for outputting a gain control signal responding to the output signal of the level detecting circuit (Det1), an offset detecting circuit (Det2) having a low-pass filter for extracting a DC component from the output signal of the A/D conversion circuit (AD1), and a D/A conversion circuit (DA1) for D/A-converting the output signal of the offset detecting circuit (Det2) thereby to output the offset compensation signal.