A phase-locked loop frequency tuning device and method

Abstract

The invention is applicable to the field of phase-locked loops, and provides a device and a method for tuning the frequency of a phase-locked loop. The device for tuning the frequency of the phase-locked loop comprises a phase-locked loop circuit and a frequency automatic tuning circuit, wherein the phase-locked loop circuit comprises a phase frequency detector, a charge pump, a loop filter, a voltage-controlled oscillator and a frequency divider which are sequentially connected. The frequency automatic tuning circuit comprises a comparison circuit and a search and decision circuit, wherein an output end of the search and decision circuit is connected to a control end of the voltage-controlled oscillator; the comparison circuit detects charging voltage of the charge pump for the loop filter; when the charging voltage is greater than first reference voltage, the resonant capacitance of the voltage-controlled oscillator is regulated and the resonant frequency of the voltage-controlled oscillator is improved; and when the charging voltage is smaller than second reference voltage, the resonant capacitance of the voltage-controlled oscillator is regulated and the resonant frequency of the voltage-controlled oscillator is reduced. According to the embodiment of the invention, rapid frequency tuning of the phase-locked loop is realized by adopting an analog circuit based decision mode, the locking time of the phase-locked loop is shortened, and the power consumption is small.

Description

technical field [0001] The invention belongs to the field of phase-locked loops, and in particular relates to a frequency tuning device and method for a phase-locked loop. Background technique [0002] figure 1 The structural principle of the phase-locked loop frequency tuning device provided by the prior art is shown, the phase-locked loop frequency tuning device includes a frequency automatic tuning circuit 1 and a phase-locked loop circuit 2, wherein the frequency automatic tuning circuit 1 includes counters 11 connected in sequence , comparator 12 and search and decision circuit 13; Phase-locked loop circuit 2 comprises frequency discrimination phase detector 21, charge pump 22, loop filter 23, voltage-controlled oscillator 24 and frequency divider 25 that are connected in sequence; Counter 11 The input end of the search and decision circuit 13 is connected to the control end of the voltage-controlled oscillator 24 . The frequency tuning of the phase-locked loop is bas...

AI Technical Summary

Problems solved by technology

[0004] The purpose of the embodiments of the present invention is to provide a phase-locked loop frequency tuning device, which aims to solve the problem that the existing phase-locked loop frequency tuning device needs a long time to get the correct result, which leads to time-consuming, complicated circuit and locking time of the phase-locked loop. long question

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