二阶PLL特性参量的一种新测试方法

A NEW METHOD OF CHARACTERISTIC PARAMETERS OF SECOND ORDER PLL

通常测量二阶锁相环(PLL) 的自然角频ωn 和阻尼系数ζ时,需要分别测量环路直流总增益和滤波器的时间常数等有关参量,此方法繁琐且误差较大.本文讨论一种通过输入小频偏的调频信号,可以方便、且较准确地测出理想二阶PLL的ωn 和ζ的实际值.该方法同样适用于非理想二阶环,以及由相位超前无源比例积分器构成的二阶环.

Generally,evaluating Nature angle-frequency ω n and damping coefficient ζ of second order PLL needs to measure it′s total gain and time constants of the filter in the PLL respectively.But in fact,there are more errors when these parameters are measured and it will take long time for us to do it,too.Using modulating frequency with small frequency deviation as inputing signal of the PLL,a short-cut method to measure ω n and ζ is discussed.By analysis,we see that the method also fits nonideal second order PLL and another PLL which consists of inactive proportion-integrator with phase lead.