Method for improving switching performance of phase-lockes loop's reference signal

Abstract

The invention discloses a method for improving switching performance of a reference signal of phase locked loop. Virtual refernece module processes the signal received. The virtual reference module is composed of a selector, a phase compensator and a phase discriminator. The selector receives a reference signal and outputs a reference signal, based on the value of the reference selection control signal. The phase discriminator also receives a signal and calculates a difference value of phase between reference signals. The phase compensator receives the value of the reference selection control signal and the reference signal output by the selector, and outputs the reference signal with the phase being compensated. Even through the reference signal is switched frequency the frequency and phase of the signal inputted to the phase locked loop are kept stabilization all the time.

Description

technical field

[0001] The invention relates to the field of signal processing in digital communications. Background technique

[0002] When the phase-locked loop is applied to digital communication equipment, there are often two external reference signals. These two external reference signals are sent to the external standard selector of the phase-locked loop, and the selector selects one of them and sends it to the phase detector of the phase-locked loop. Can improve the reliability of the system. But it also brings another problem, because the two external reference signals generally have the same frequency but the phase difference is random. In this way, when the external reference signal is switched, for the PLL phase detector, the phase of the input signal has a large jump, and when the external reference signal switches frequently, it may even cause the phase-locked loop to lose lock. This problem is a more serious problem in the communicatio...

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