VARIABLE GAIN CIRCUIT

摘要

It is possible to realize a low distortion even at a strong input level and maintain a smooth gain change. A variable gain circuit includes a first amplifier (10) of high gain and low noise capable of controlling the gain by a first gain control signal, a second amplifier (20) of low gain and low distortion capable of controlling the gain by a second gain control signal, and a third amplifier (30) connected to outputs of the first and the second amplifier (10, 20). The input terminal of the first amplifier (10) is connected to the input terminal of the second amplifier (20) and the output terminal of the first amplifier (10) is connected to the output terminal of the second amplifier (20). The output of the first amplifier (10) is turned ON or OFF by a mode switching signal. The gain change by ON/OFF of the first amplifier (10) is corrected by the third amplifier (30).