SOG signal detection circuit

摘要

A Sync On Green signal detection circuit includes a clamping circuit for clamping a voltage of a video graphics signal within a default range and then outputting a clamped input signal; a first PGA (programmable gain amplifier) for receiving and amplifying the clamped input signal by a first gain to generate a first gain signal; a first low-pass filter for receiving the first gain signal and then generating a first filtered signal; a second PGA for receiving and amplifying the clamped input signal by a second gain to generate a second gain signal, wherein the second gain is different from the first gain; a second low-pass filter for receiving the second gain signal and then generating a second filtered signal; a programmable voltage shifter for receiving and adjusting the first filtered signal and then outputting a level shifted signal; and a comparator for receiving the level shifted signal and the second filtered signal and then generating a comparison signal as a SOG signal.