Frequency band switching method and frequency band switching system for phase-locked loop

Abstract

The invention discloses a frequency band switching method and a frequency band switching system for a phase-locked loop, and the frequency band switching method and the frequency band switching system belong to the technical field of electronics. The frequency band switching method comprises the steps of judging a size relationship between a count value of a current output frequency of a voltage-controller oscillator and a count value of an expected frequency and adjusting the current output frequency band according to the size relationship so as to determine an upper frequency band and a lower frequency band, frequencies of which have the minimal difference value with the expected frequency; and comparing the size of difference values between the count value of the expected frequency andcount values of the frequencies of the upper frequency band and the lower frequency band under a fixed voltage so as to determine the frequency band, the frequency of which has the minimal differencevalue with the expected frequency, as the switching frequency band, and switching the current output frequency band to the switching frequency band. The system comprises a rated time pulse generator,a counter and a logic controller. The frequency band of the voltage-controller oscillator is adjusted in place by one step by utilizing the difference between the count value of the expected frequency and the count value of the oscillation frequency of the central frequency band of the voltage-controller oscillator under the fixed control voltage, thereby saving the frequency band switching time and increasing the switching speed of the frequency band.

Description

technical field [0001] The invention relates to the field of electronic technology, in particular to a frequency band switching method and system for a phase-locked loop. Background technique [0002] In the field of wireless communication, many systems are required to cover a wide frequency range, and the broadband phase-locked loop that can realize this requirement has become a key module of each communication system. In this wide-band application, if the phase-locked loop has no frequency band division, and the frequency switching is directly controlled by the control voltage, it will inevitably lead to a sharp increase in the gain of the voltage-controlled oscillator, which means that a small change in the control voltage will cause the oscillator The severe frequency jitter affects the stability and noise performance of the entire phase-locked loop. Therefore, the frequency range of the oscillator is generally divided into several sub-frequency bands that overlap each ...

AI Technical Summary

Problems solved by technology

[0005] In order to solve the problems such as the long frequency band adjustment time of the existing phase-locked loop and the slow frequency band switching speed, the present invention provides a frequency band switching method for the phase-locked loop, the method comprising:

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