VIDEO SIGNAL PROCESSING CIRCUIT

摘要

PURPOSE:To prevent S/N from being deteriorated even when a 2nd LPF is integrated into an IC as a nonlinear active element by disposing a 1st LPF suppressing a higher frequency triangle noise component than a MUSE signal frequency band behind an FM demodulation circuit. CONSTITUTION:A 2nd intermediate frequency signal being the output of a turning circuit 10 is FM-demodulated with an FM demodulation circuit 11, and an FM detection signal in which a video signal and an audio signal subcarrier are subjected to frequency division multiplexing is obtained. The FM detection signal has a so-called triangle noise signal in which the noise components are increased as the frequency gets higher and a 1st LPF 30 eliminates a high frequency noise component. Thus, the generation of undesired noise in a video signal band due to the saturation of a 2nd LPF 23 whose frequency is 4.5MHz constituted of an active element built in an IC due to out-band noise is avoided by disposing the 1st LPF 30 interrupting the noise power in advance at the out-band of the video signal behind the FM demodulation circuit 11.