说明：  鉴相器（phasedetector）指的是能够鉴别出输入信号的相位差的器件，是使输出电压与两个输入信号之间的相位差有确定关系的电路。它是PLL，即锁相环的重要组成部分。
(Phase discriminator is a device that can identify the phase difference of input signal. It is a circuit that makes the phase difference between output voltage and two input signals have a definite relationship. It is an important part of PLL.)