CHROMA SIGNAL GAIN CONTROL CIRCUIT

摘要

: A chroma signal gain control circuit is constructed to include a first band pass amplifier, a second band pass amplifier, a burst gate circuit, a switch circuit and an ACC detecting circuit. The output signal of the first band pass amplifier is fed to the input of the second band pass amplifier, the output signal of which is fed to the input of the burst gate circuit. The switch circuit selectively transmits either the output of the burst gate circuitry or the output of the second band pass amplifier to the ACC detecting circuit. The gain of the first band pass amplifier is controlled by feeding the detected output of the ACC detecting circuit to the first band pass amplifier. In order to prevent saturation when the level ratio (C/B) between the color burst signal and the chroma signal exceeds a predetermined value, the switch circuit transmits the output of the second band pass amplifier to the ACC detecting circuit.