Method and apparatus for achieving fast phase-settling in a phase-locked loop

摘要

A method and an apparatus are provided to achieve fast phase settling when a reference signal for a phase locked loop changes from a first frequency to a second frequency, such as during holdover recovery in a synchronous optical network. The present method acquires the second frequency with a phase locked loop (24). After the frequency is acquired, the integral register (39) of the phase locked loop (24) is loaded with the contents of the output frequency register (34) of the phase locked loop (24). The phase detector (28) of the phase locked loop (24) is then realigned to the reference signal.