Automatic gain control circuit of a video processing system and method therefor

Abstract

An automatic gain control circuit for controlling gain according to a sound gain controller so as to output a stable video intermediate frequency signal includes a first gain control amplifier receiving a video intermediate frequency signal, for amplifying the signal by a sound gain control voltage and for then producing an amplified video intermediate frequency signal, a second gain control amplifier receiving a carrier signal having a sound intermediate frequency signal and a video intermediate frequency signal, for amplifying the carrier signal by the sound gain control voltage and for then providing the amplified carrier signal, and a sound gain control voltage detecting circuit for receiving the amplified signal from the second gain control amplifier, for detecting the sound gain control voltage and for then providing the detected sound gain control voltage to thereby automatically control the gain of said first gain control amplifier. A method for operating an automatic gain control amplifier is also described.

Dependencies are inferred from the claim text.