IMPROVEMENT OF PHASE-LOCKED LOOPS BY THE INTRODUCTION OF NONLINEARITIES.
Abstract
Reported herein is a technique which improves the large signal performance of phase-locked loops. The method consists of replacing the linear loop filter with a nonlinear filter. The technique allows the phase-locked loop system designer considerably more design freedom with respect to phase error linearity, lock range, lock rate range and synchronization time. This is particularly evident for higher order systems. The nonlinear operators used in constructing the nonlinear loop filter are specified in detail for first and second order phase-locked loops. Typical design criteria are used in specifying the operators; however, the extension to any other design criterion is obvious. The methods apply equally well to higher order phase-locked loops once a specific set of design criteria are established. Unlike other techniques used to improve large signal performance of phase-locked loops, the technique discussed is extremely simple to implement. In addition, the technique applies to all types of phase-locked loops independent of the type of phase comparator. Theoretical results and conclusions for first and second order systems are verified by experimental systems constructed on an analog computer. Certain results, which are difficult to determine using analog methods, were obtained with the aid of a digital computer. The experimental data were found to agree very well with those predicted theoretically. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 1968
- Accession Number
- AD0674934
Entities
People
- B. J. Leon
- L. L. Cleland
Organizations
- Purdue University