Introduction to phase-locked loop system modeling

tingwu7

By Wen Li, Senior System Engineer, Advanced Analog Product Group
and Jason Meiners, Design Manager, Mixed-Signal Product Group

Introduction
Phase-locked loops (PLLs) are one of the basic building blocks in
modern electronic systems. They have been widely used in
communications, multimedia and many other applications. The
theory and mathematical models used to describe PLLs are of two
types: linear and nonlinear. Nonlinear theory is often complicated
and difficult to deal with in real-world designs. Analog PLLs have
been well modeled by linear control theory. Starting from a
well-defined model in the continuous-time domain, this article
introduces a modeling and design method for a digital PLL based
on linear control theory. It has been proved that a linear model is
accurate enough for most electronic applications as long as certain
conditions are met. Figure 1 shows a block diagram of the Texas
Instruments THS8083 device that targets LCD monitor and digital
TV applications. The task of the PLLs in these devices is to recover
the pixel clock based on input reference HS (horizontal sync). This
PLL has been accurately modeled by the method introduced in this
article.

violetzhao

谢谢分享

xlteam2

very useful

fwutsairlin

thanks!