Because of PLL output signal frequency can be achieved on the input signal frequency automatic tracking, Therefore, normally used for closed-loop tracking phase-locked loop circuit. Phase-locked loop in the course of work, when the output signal frequency and the same input signal frequency, the output voltage and input voltage to maintain a fixed phase difference value, that is, the output voltage and input voltage of the phase was locked, which is phase-locked Central origin of the name.
This paper mainly introduces the basic principles of phase-locked loop, application, performance, features, concepts. Introduced the PLL is currently common to analyze the working principle of the phase-locked loop, focusing on the design and implementation of phase-locked loop.
Key words: phase-locked loop, automatic tracking, a fixed phase difference
