Phase-locked loop

摘要

In a phase-locked loop, the output of a digital phase comparator is connected to the control input of a change-over switch, the input of which is connected to a pulse generator. One output of the change-over switch is connected to the up-counting and the other output is connected to the down-counting input of a counter. The N outputs of the counter are connected to the N inputs of a switching matrix, the output of which is connected to the input of a voltage-controlled oscillator. The output of the voltage-controlled oscillator is connected to one input of the phase comparator whilst a signal with a reference frequency is present at its other input.