Crosstalk bounded uncorrelated jitter (BUJ) for high-speed interconnects

Bounded uncorrelated jitter (BUJ), a subcomponent of total jitter, is commonly caused by crosstalk coupling from adjacent interconnects on printed circuit boards (PCB). However, the characteristics of BUJ are still not well understood. Neither a mathematical model of jitter, nor an algorithm to generate histograms for BUJ has been developed to this date. Such a model and algorithm would empower designers to predict BUJ to achieve total jitter budget without lengthy simulations and measurements. In this paper, we first review the characteristics of a crosstalk pulse induced by an aggressor signal on a quiet trace. Then, by applying the superposition principle, a jitter model to calculate the time difference between the distortion-free and the distorted edge crossings of the victim signal was developed. This model is also extended to calculate the worst case timing difference, BUJ/sub p-p/. In addition, an algorithm to generate the histogram distribution of BUJ is also developed. The developed algorithm has fast execution times of 10-20 s, compared to simulation and measurement times of 10-30 min.

I. Introduction

THE RECENT deployment of high-speed I/O interconnects raises considerable signal integrity issues. Such signal integrity issues include ringing, reflections, electromagnetic interference (EMI), ground bounce, switching power supply noise, and crosstalk [1]. In addition, as bus speeds increase over the years, the timing budget of I/O interconnects decreases exponentially [2]. This places a stringent requirement on the total jitter budget. Fig. 1. Subcomponents of total jitter.