Phase-locked loop for frequency synthesis e.g. in mobile radio, controls oscillator with time-averaged fraction rational value of digital controls signal related to quantization step

摘要

The phase-locked loop includes a sigma-delta modulator (8) for controlling an oscillator (1), with a time-averaged fractional rational value of a digital control signal related to the quantization step size of the digitally controlled oscillator. The sigma-delta modulator couples the output of a phase detector (5) to the control input (2) of the oscillator.