Abstract

This paper represents a simple and easy to learn method for analysis and design of third-order charge pump phase-locked loop (PLL) and provides analytical equations for calculating the desired specifications such as phase margin (PM), damping ratio and small signal settling time. The proposed method is based on dominant pole approximation. In other words, this method is based on the approximation of the transfer function of the third-order PLL through transfer function as a second order system. The validity of the obtained analytical equations has been verified in two examples. Simulation results of the introduced method demonstrate precision in designed parameters.

Key words: Charge pumps phase-locked loop (PLL), phase detector, phase margin (PM), settling time, damping ratio, natural frequency.

Abbreviation

PLL, Phase-locked loop; PVT, process, voltage, and temperature; PFD, phase frequency detector; VCO, voltage controlled oscillator; PM, phase margin.