All-digital phase locked loop and fast phase locking method thereof

Abstract

The invention discloses an all-digital phase locked loop and a fast phase locking method thereof, wherein the fast phase locking method comprises the following steps: detecting whether a falling edgeof a currently input reference signal arrives, when the falling edge of the reference signal arrives, outputting a reconstructed signal by a digital-controlled oscillator; performing frequency division for the reconstructed signal and then comparing the reconstructed signal with the frequency of the reference signal, and outputting a corresponding level signal according to a comparison result; according to the level signal, coarsely regulating a value of a frequency control word according to a preset rule to adjust output frequency of the reconstructed signal; when times of coarse regulation reaches preset times, finely regulating the value of the frequency control word according to a phase relation of the reconstructed signal and the reference signal, thereby enabling the frequency of thereconstructed signal subjected to frequency division to be equal to the frequency of the reference signal, and enabling the all-digital phase locked loop to enter into a locked state. By the method,locking time of the phase locked loop is only related to frequency range and precision of output, moreover, times of search is reduced effectively through coarse regulation and fine regulation with different step sizes, the locking time is reduced and fast phase locking is realized.

Description

technical field [0001] The invention relates to the technical field of phase-locked loops, in particular to an all-digital phase-locked loop and a fast phase-locked method thereof. Background technique [0002] A Phase-Locked Loop (PLL) is a negative feedback control circuit that can automatically track an input signal. The so-called phase locking, as the name implies, is to use the phase difference between the input and output signals to automatically adjust the phase, so that the frequency of the output signal automatically tracks the frequency of the input signal, and finally completes the phase synchronization and automatic frequency tracking between the two signals. function. Phase-locking technology is an important automatic feedback control technology, which has been widely used in many fields, such as instrumentation, communication and digital signal processing. [0003] The current fully integrated transceiver SOC is rapidly developing in the direction of multi-mo...

AI Technical Summary

Problems solved by technology

[0004] At present, there are many technologies applied to fast locking, such as increasing the reference clock frequency, loop bandwidth adaptive technology, feed-forward compensation technology and frequency control word preset technology, etc., these existing traditional full digital phase-locked loops The locking time of (ADPLL) is related to the output frequency range, filter bandwidth, target frequency and frequency accuracy. The larger the output frequency range, the smaller the filter bandwidth, the farther the target frequency is from the starting frequency, and the higher the frequency accuracy is. The longer the locking time, thus limiting the development of fast phase-locking technology

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