Abstract: Phase locked loop (PLL) is performed as the source of the wireless communication system to complete modulation, demodulation, spectrum transform and so on. As a typical negative feedback system, the system level design and parameter selection directly determine the quality of PLL. In this paper, a behavioral model of phase locked loop based on Matlab/Simulink is proposed. Through the dynamic simulation, beginners can quickly master the working principle of the PLL, understand the tradeoff between loop bandwidth, phase margin and the setting time, provide guidance for circuit design.

Key words: Simulink, Matlab, frequency synthesizer, behavioral modeling