Worst-case noise prediction using power network impedance profile

Abstract

We propose a novel method to predict the worst-case noise using power distribution network impedance profile. Traditional target impedance method lacks of accuracy to estimate the worst-case noise. The convolution of impulse responses method can provide accurate noise prediction but cannot provide intuitive guidelines for the optimization. In this paper, we first analyze the ratio of the time-domain maximum output voltage noise to the multiplication of target impedance when time-domain maximum input current is confined to one. Particularly, for a typical PDN with two-stage or three-stage RLC tanks, the maximum ratio can be 2.09 and 2.72 respectively. We then propose our prediction in a standard RLC tank. We further extend it to analyze real PDN structures with multistage RLC tanks. Our results show that the proposed method can intuitively and accurately estimate the worst-case noise and provide straightforward design guidelines to improve PDN performance. For a typical lumped PDN with two-stage RLC tanks, the estimation error is within ±6%.