Analysis of a Phase-Locked Loop and a General Feedback System with a Limiter

摘要

A phase-locked loop (PLL) with a hard limiter and wide-band noise input is analyzed. A powerful method introduced in Kushner's 'Diffusion approximations to output processes of nonlinear systems with wide band inputs, and applications' for obtaining a close diffusion approximation to a system with the limiter greatly improves the tracking and acquisition properties over the classical PLL. This is demonstrated theoretically and supported by simulation results. Similar results hold for a standard feedback control problem with a limiter at the beginning of the forward loop. The results are a clear demonstration of the value of the new techniques of analysis which are employed. The techniques are applicable to other communications systems with nonlinearities and wide-band inputs. (Author)