中文说明：锁相环（PLL）是一种闭环反馈控制系统，它产生并输出与输入（“参考”）信号的频率和相位有关的信号。锁相环电路对输入信号的频率和相位都作出响应，自动提高或降低受控振荡器的频率，直到它在频率和相位上与基准相匹配。
English Description：
A phase-locked loop (PLL) is a closed-loop feedback control system that generates and outputs a signal in relation to the frequency and phase of an input ("reference") signal. A phase-locked loop circuit responds to both the frequency and the phase of the input signals, automatically raising or lowering the frequency of a controlled oscillator until it is matched to the reference in both frequency and phase. This type of mechanism is widely used in radio, telecommunications, computers and other electronic applications where it is desired to stabilize a generated signal or to detect signals in the presence of noise. Since an integrated circuit can hold a compl