General method for phase-locked loop filter analysis and design

The analysis and design of high-order phase-locked loops (PLLs) is difficult. A novel approach is presented which allows high-order loops to be viewed as a natural extension of lower- order ones. Type I low-order PLLs are considered a starting point for the design of higher type, higher-order PLLs. Starting with lower-order PLLs not only permits a comprehensive classification of all practical kinds of PLLs but also facilitates their design from a more intuitive perspective. The model presented, based on the loop filter composed of several nested first-order feedback loops, has been implemented and tested in Simulink^reg, confirming the ideas presented.