The Analysis of Phase-jitter Variance in the Third-order CPPLL Frequency Synthesizer

In this paper, we derive the upper bound of the phase-jitter variance of third-order charge-pump phase-locked loops. We employ the simple linear model in the beginning and integrate the power spectral density functions from different noise sources to determine the closed form for an upper bound of the phase-jitter variance. The noise sources we have considered in this paper are the phase noise from the VCO, the noise from the charge pump, the noise from the loop filter, and the noise in the reference clock. Some experiments are performed to verify the proposed theory. The curves of the theoretical upper bounds possess similar shapes with the experimental results