method for optimizing the phasenregelkreis transfer function and the corresponding phasenregelkreis

摘要

The invention relates to a phase-locked loop circuitry structure, especially for use in a clock and data recovery device, the circuitry structure at least comprising concatenated in series phase detector means, low-pass filter means and voltage controlled oscillator means, the phase detector means providing an output signal depending on the phase difference of a reference input signal and a feedback signal and further comprising feedback means for feeding back the output signal of said voltage controlled oscillator means to said phase detector means in order to minimize the phase difference of said reference input signal and said feedback signal or to keep said phase difference to an essentially constant value. According to the invention, the phase detector means, low-pass filter means and voltage controlled oscillator means have such individual transfer functions that the closed-loop transfer function H(s) of the phase-locked loop circuitry is an all-pole function of the order n of the form H(s)=K/(s+a)n, where K and a are design parameters determined at least by the low-pass filter means, where s is the complex frequency and where n is an integer number equal to or greater than 2, resulting in a critically damped closed-loop transfer function. Moreover, the invention relates to a method for optimizing the transfer function of a phase-locked loop circuitry structure.