AUTOMATIC GAIN CONTROL CIRCUIT, IN WHICH IT IS EASILY INTEGRATED INTO INTEGRATED CIRCUIT WITHOUT REQUIRING ANY SIGNAL INTEGRATION CIRCUIT BY USING CAPACITOR

摘要

PURPOSE: An automatic gain control(AGC) circuit is provided to easily incorporate into an integrated circuit without requiring any signal integration circuit by using a capacitor. CONSTITUTION: An automatic gain control(AGC) circuit includes a variable gain amplifier circuit(1), a rectification circuit(2), a first voltage comparator(3), a threshold voltage input terminal(4), a first up/down counter(5), an up/down operation control input terminal(6), an input terminal(7) for inputting an up-count operation clock(V5) and an input terminal(8) for inputting a down-count operation clock(V6). The variable gain amplifier circuit amplifies or attenuates a voltage of input signal(VA) in accordance with a gain controlled by a gain control voltage(V8) to output an output signal(VB). The rectification circuit rectifies the output voltage of the variable gain amplifier circuit. The first voltage comparator compares the rectified signal(V1) rectified by the rectification circuit with a preset arbitrary threshold voltage(V2). The threshold voltage input terminal inputs the threshold voltage to the first voltage comparator. The up/down operation control input terminal inputs the output voltage(V3) of the first voltage comparator as a control signal(V4) to control the up/down operation.