RDE-based transistor-level gate simulation for statistical static timing analysis

Abstract

Existing industry-practice statistical static timing analysis (SSTA) engines use black-box gate-level models for standard cells, which have accuracy problems as well as require massive amounts of CPU time in Monte-Carlo (MC) simulation. In this paper we present a new transistor-level non-Monte Carlo statistical analysis method based on solving random differential equations (RDE) computed from modified nodal analysis (MNA). In order to maintain both high accuracy and efficiency, we introduce a simplified statistical transistor model for 45nm technology and below. The model is combined with our new simulation-like engine which can do both implicit non-MC statistical simulation and deterministic simulation fast and accurately. The statistics of delay and slew are calculated by means of the proposed analysis method. Experiments show the proposed method is both run time efficient and very accurate.