Test method for step response performance of phase-locked loop system

Abstract

The invention discloses a testing method for the step response performance of a phase-locked loop system, aiming at improving the testing precision of the step response performance. The testing method comprises the steps as follows: during the process that the phase-locked loop system steps from one stable oscillating frequency to another oscillating frequency, the waveform of an output voltage signal is recorded; the frequency information of the output voltage signal during the stepping process is obtained according to the waveform; and parameters of the step response performance are obtained according to the frequency information. The invention avoids leading testing parameters from a feedback loop, can not lead noise to an original system and improves the measuring precision.

Description

technical field [0001] The invention relates to a phase-locked loop system, in particular to a method for testing the step response performance of the phase-locked loop system. Background technique [0002] Phase-locked loops are a very useful synchronization technique in applications such as data acquisition. The phase-locked loop is actually a feedback circuit, which is characterized by using an externally input reference signal to control the frequency and phase of the internal oscillation signal of the loop, so that the phase of the internal clock of the loop and the reference signal clock are synchronized. During the working process of the phase-locked loop, when the frequency of the output voltage signal is equal to the frequency of the reference signal, the output voltage and the input voltage maintain a fixed phase difference, that is, the phase of the output voltage and the input voltage is locked, which is the lock The origin of the phase ring name. [0003] fig...

AI Technical Summary

Problems solved by technology

Due to the control voltage S of the VCO 30 d As a node in the entire loop of the phase-locked loop, it is not convenient to lead from between the loop filter 20 and the voltage-controlled oscillator 30, which increases the difficulty of direct testing

Moreover, even if the control voltage of the voltage-controlled oscillator 30 is taken out from between the loop filter 20 and the voltage-controlled oscillator 30, the control voltage S d It is also easily affected by external noise, which brings measurement errors and cannot obtain accurate measurement values

Images