Copyright © 2008 Tzung-Je Lee and Chua-Chin Wang. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

A phase-locked loop (PLL) using separate regulators to reject the supply noise is proposed in this paper. Two regulators, REG1 and REG2, are used to prevent the supply noise from the charge pump (CP) and the voltage-controlled oscillator (VCO), respectively. By using separate regulators, the area and the power consumption of the regulator can be reduced. Moreover, the jitter of the proposed PLL is proven on silicon to be less sensitive to the supply noise. The proposed PLL is fabricated using a typical 0.35 μm 2P4M CMOS process. The peak-to-peak jitter (P2P jitter) of the proposed PLL is measured to be 81.8 ps at 80 MHz when a 250 mVrms supply noise is added. By contrast, the P2P jitter is measured to be 118.2 ps without the two regulators when the same supply noise is coupled.