Phase-locked loop

What is it about?

Phase locked loop is a negative feedback control system that uses voltage generated by phase synchronization to tune a voltage controlled oscillator to generate a target frequency. According to the principle of automatic control, this is a typical feedback control circuit that uses an external input reference signal to control the frequency and phase of the internal oscillation signal in the loop, achieving automatic tracking of the output signal frequency to the input signal frequency. It is generally used in closed-loop tracking circuits.