RMS frequency error performance and spurious signals in two-point modulators due to path imbalances

Authors : Gökhun SELÇUK, Kaan ÜÇEL

Pages : 432-442

Doi:10.3906/elk-1804-141

View : 22 | Download : 9

Publication Date : 0000-00-00

Article Type : Research Paper

Abstract :In this study the authors introduce an analysis of rms frequency error performance and spurious signals generated by two-point modulators. The analysis is not limited to a constant delay and magnitude imbalance between modulation paths but allows frequency-dependent group delay and amplitude variations as well. Moreover, a discrete time phase frequency detector model is incorporated in Laplace domain analysis that takes into account the sampling nature of a phase-locked loop PLL . Using the spectrum of pulse width modulated charge pump pulses, the spurious signals at the output of the PLL are evaluated. The proposed formulae are tested on a practical setup and quite accurate results are obtained.
Keywords : Frequency error, phase locked loop, pulse width modulation, two point modulator