PLL circuit and phase lock detector

摘要

The circuit has a low pass filter (30) connected between two charge pump circuits and a voltage controlled oscillator (107) to smooth output of the pump circuits. A lock detector detects if an oscillation clock maintains a constant phase difference relative to a reference clocks phase. A selecting circuit operates the respective pump circuits when the oscillation clock maintains/does not maintain constant phase difference. An independent claim is also included for an image signal processing apparatus for producing chrominance information and luminance information.