如下：
1、A phrase loop contain three components:a phrase detector,a loop filter and a voltage-controlled oscillator(VCO)whose frequency is controlled by an external voltage.The phase detector(PD)compares the phase of a periodic input signal against the phase of the VCO.Output of PD is a measure of the phase difference between its two inputs.The difference voltage is then fiftered by the loop filter and applied to the VCO.
2、For each cycle of input there is one,and only one,cycle of oscillator output.One obvious application of phaselock is in automatic frequency control(AFC).Perfect frequency control can be achieved by this method,whereas conventional AFC techniques necessarily entail some frequency error.手机打的,累死我了
