pll and adaptive compensation method in pll

Abstract

In a method for mitigating vibration-induced phase noise in a phase-locked loop with an acceleration-sensitive voltage-controlled oscillator, active compensation is added to the oscillator control signal by adding a correction signal to the The acceleration signal provided by the acceleration sensor on the VCO is generated by applying gain and equalization. The adaptive compensation unit dynamically adjusts the gain, the frequency response of the balance and the sensing direction of the acceleration sensor while the phase-locked loop is working, so that the active compensation automatically adapts to the parameters of the VCO. The acceleration signal and the filtered phase difference signal generated by a filter following the phase frequency detector of the phase locked loop are provided at the input of the adaptive compensation unit. In the adaptive compensation unit, the cross-correlation unit calculates the correlation coefficient and delay between the acceleration signal and the filtered phase difference signal, the gain generation unit incrementally calculates the gain and the sensing direction of the acceleration sensor according to the correlation coefficient, and the equalization coefficient estimator Filter coefficients of a filter performing equalization are incrementally calculated based on the acceleration signal, the filtered phase difference signal and the calculated delay.

Description

technical field [0001] The present disclosure relates to the field of electronic circuits, and in particular to phase-locked loops (PLLs), devices including PLLs, and methods of adaptive compensation in PLLs. Background technique [0002] Crystals (such as quartz crystal oscillators) are widely used in frequency resources of electronic circuits, such as jitter cancellers and frequency synthesizers. However, it is also known that the natural resonance frequency of such crystals changes when the crystal is subjected to acceleration (cf. Ref. [1]). Due to the acceleration sensitivity of a crystal oscillator, mechanical vibrations can introduce additional phase noise to its output clock, which can detrimentally lead to performance degradation or even failure for various applications. [0003] Vibration effects are evident in three real-world scenarios: 1) wireless base stations on iron towers shaken by wind, passing trucks, or earthquakes; Wireless communication terminals, rad...

AI Technical Summary

Problems solved by technology

It only works with all-digital PLLs and is not designed to suppress phase noise introduced by vibration

[0012] Existing passive and active approaches suffer from certain disadvantages which either limit its performance or result in high product cost

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