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在分析电荷泵锁相环基本原理的基础上,给出了三级电荷泵锁相环的线性相位模型以及三级电荷泵锁相环的开环和闭环传输函数,结合具体的设计实例利用三级电荷泵锁相环的环路传输函数在MATLAB中对该锁相环进行了系统级设计,最后在SIMULINK中建立了该三级电荷泵锁相环的行为模型,分析系统的建立时间和频率响应等特性。该模型不但可以快速评估环路参数变化对CPPLL瞬态特性的影响,而且可以在模型中引入适当的噪声源,并分析其对输出相位噪声的影响。仿真结果符合设计要求,这种方法同样适合高阶电荷泵锁相环的设计和分析。
Based on the analysis of the fundamental principle of the charge pump PLL, the linear phase model of the three-phase charge pump PLL and the open-loop and closed-loop transfer functions of the three-phase charge pump PLL are given. Combining with the design example, Level charge pump phase-locked loop loop transfer function of the phase-locked loop in MATLAB system-level design, and finally established in the SIMULINK the three-stage charge pump phase-locked loop behavior model, analysis of system setup time and frequency Response and other features. The model can not only quickly assess the influence of loop parameters on the transient characteristics of CPPLL, but also introduce appropriate noise sources into the model and analyze its influence on output phase noise. Simulation results meet the design requirements, this method is also suitable for high-end charge pump phase-locked loop design and analysis.