Phase locked loop for phase/frequency modulation, has low pass filter controlling oscillator using voltage at capacitor terminal, and switch, between filter and terminal, controlled to insulate filter from capacitor during pulse generation

摘要

The loop has a phase comparator generating a measurement signal with pulses, based on phase difference between divided frequency and reference signals. A low pass filter (34) controls a voltage controlled oscillator using voltage at a terminal of a capacitor (50) receiving load current from a load pump (33). A switch (51) placed between filter and terminal is controlled to insulate the filter from the capacitor during pulse generation.