PLL CIRCUIT FOR REINFORCING FREQUENCY BAND WIDTH

摘要

The band enhanced PLL circuit is for filtering audio carrier signal of satellite broadcasting system by adopting variable frequency oscillator having frequency band of 5.0MHz to 8.5MHz. The circuit includes a microprocessor(10) for generating data signal and control signal, a phase filter(20) for generating an error pulse by comparing selected values corresponding to a selected carrier signal and a former carrier signal, a lowpass filter(LPF) for converting output signal of the phase filter into a DC level, and an oscillator(30) for generating frequency signal having frequency varying according to output signal of the LPF.