Phase locked loop circuit arrangement for frequency multiplication in video or television applications

摘要

The circuit includes a digital filter which provides the input signal and a reference signal from the oscillator output, and provides the pilot signal pulses. A digital filter (6) receives an input pilot signal, to provide an output signal (200) and a reference signal (201). These are both rectangular shaped signals and are supplied to phase detector (4). There is a voltage-controlled oscillator (5) adjustable in a predetermined target range, from whose output signal (501) the reference signal is derived through a logic circuit (2). The logic circuit includes the digital filter (6) which provides the input signal and the reference signal for the phase detector from the output signal of the oscillator and a pulse-shaped pilot signal (100). The filter is formed such that if the pilot signal has a to high pulse sequence, which leads to an overstepping of the upper boundary of the target range of the oscillator, the input signal is generated from the pilot signal through periodical suppression of the pilot signal.