Loop bandwidth test algorithm module for phase-locked loop

Abstract

The invention brings forward a loop bandwidth test algorithm module for a phase-locked loop, and aims at providing the loop bandwidth test algorithm module, which is simple in test process and high in measuring accuracy, for the phase-locked loop. The invention is realized by the following technical scheme: an output end of a control module is respectively connected with a digital direct signal synthesizer and a phase monitoring and bandwidth calculating module so that a loop bandwidth test algorithm circuit for the phase-locked loop is formed. In testing, the tested phase-locked loop is connected in series between the digital direct signal synthesizer and the phase monitoring and bandwidth calculating module. The error phase output of the tested phase-locked loop is monitored by the phase monitoring and bandwidth calculating module. The digital direct signal synthesizing module generates a single frequency sinusoidal signal with a phase step, and the single frequency sinusoidal signal is inputted to the tested phase-locked loop. A time difference starting from the phase step to a second zero crossing moment is measured, and the loop bandwidth is measured according to the time difference. The loop bandwidth is measured by monitoring the error phase so that a problem of measurement of narrow band loop bandwidth is solved.

Description

technical field [0001] The invention relates to an algorithm module for testing the loop bandwidth of a phase-locked loop based on a digital circuit. Background technique [0002] At present, the loop bandwidth test of the phase-locked loop design based on digital circuits mainly adopts the method of frequency domain measurement, and the purpose of loop bandwidth measurement is achieved by analyzing and comparing the frequency spectrum of the phase-locked loop input and output. [0003] In engineering applications, the phase-locked loop bandwidth is tested from the frequency domain through the test methods of phase modulation and frequency modulation. The basic principle is to generate modulated harmonics through frequency modulation or phase modulation, and input the modulated signal into the phase-locked loop. Filtering, the amplitude measurement of the residual harmonics after filtering is used to test the loop bandwidth. The disadvantages of this frequency-domain-based ...

AI Technical Summary

Problems solved by technology

The disadvantages of this frequency-domain-based test method are: the test process is complicated, and spectrum analysis needs to be repeated; the test time is long; the test accuracy is low, and it is difficult to apply to narrow-band phase-locked loops

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