Jitter-induced power/ground noise in CMOS PLLs: a design perspective

CMOS phase-locked loops (PLL) are ubiquitous in RF and mixed-signal integrated circuits. PLLs are very sensitive to noise fluctuations on the power and ground rails. In this paper, a general comprehensive stochastic model of the power/ground (P/G) noise in VLSI circuits is presented. This is followed by calculation of the phase noise of the voltage-controlled oscillator (VCO) in terms of the statistical properties of supply noise. The PLL timing jitter is predicted in response to the VCO phase noise. Next, the design of a low power, 2.5 V, 0.25 μ CMOS PLL clock generator with a lock range of 100 MHz-400 MHz is described. Our mathematical method is utilized to study the jitter-induced P/G noise in this PLL. A comparison between the results obtained by our mathematical model and those obtained by HSPICE simulation prove the accuracy of the predicted model