CLAMP CIRCUIT OF VIDEO DECODER AND METHOD FOR CONTROLLING CLAMP LEVEL THEREOF

摘要

PURPOSE: A clamp circuit of a video decoder and method for controlling clamp level thereof are provided to compensate the level shift of the reference level of the clamp level circuit. CONSTITUTION: A clamp circuit of a video decoder includes an alternative wave coupling capacitor(Cc), a clamp level controller(20), an amplifier(40), an analog/digital converter(50) and a control signal generator(60). The alternative wave coupling capacitor(Cc) couples an analog image signal. The clamp level controller(20) controls the horizontally synchronous signal generated at one end of the alternative wave coupling capacitor(Cc) with a reference clamp level. The amplifier(40) amplifies the output image signal from the clamp level controller. The analog/digital converter(50) converts the image signal amplified at the amplifier to a digital signal. The control signal generator(60) generates a control signal according to the compared result of the reference value to a digital image signal.