高阶有源锁相环路滤波器的设计与仿真

基于频率响应的设计方法,本文对四阶电荷泵锁相环滤波器进行了设计和仿真,利用时间常数与滤波器组件的关系,推导和分析了环路滤波器的传递函数,并在Matlab环境下仿真得到了理想的相位裕度和环路带宽.实验表明,该高阶有源锁相环路滤波器可以在保证相同的鉴相杂散抑制的同时,可允许更宽的环路带宽和更高的鉴相频率,从而改善了锁相环的带内相位噪声性能.

Design and Simulation of High Order Active PLL Filter

A design of fourth order charge pump PLL is designed with the method of frequency response.And the loop filter transfer function is deduced.According to relationship between the time constant and the filter component,the loop filter is calculated by the use of Matlab.The result shows that both the desired phased margin and loop bandwidth are acquired and wider loop bandwidth and higher detector frequency are achieved,which in turn improves the in-band phase noise of the PLL.