An Analysis of Phase-Locked Loops.
NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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An investigation was conducted of a third order type two phase-locked loop with a sawtooth phase comparator using both analog and digital simulation techniques and employing an exact system simulation. The results are presented in terms of normalized system parameters and give the system performance as a function of the initial phase between the input and the VCO waveforms, the variation of the input from the VCO frequency, and the system gain and filter characteristics. Some of the data presented includes the time required for the system to meet different types of lock criterion together with the range of frequencies over which the system will lock and the range over which it will lock without cycle skipping. Investigations were conducted of the system performance for eight different types of phase comparators, of which two of the basic forms had been used previously and the rest were new with this work. It was found that two of the new forms, the R-S nonlinear and the additive with ramp nonlinearity exhibited significantly superior performance in that they possessed increased lock ranges, reduced lock times, and greater values of seize frequency than did the basic systems from which they were derived. It was found that three of the phase comparators yielded an unlimited lock range, even though the lock time became quite long for very large frequency variations. Author
- Electricity and Magnetism