Hierarchical analysis of process variation for mixed-signal systems

Increasing process variability necessitates reliable analysis of its effects on circuit performance not only at the top level but also at intermediate levels. Mixed-signal circuits with multiple hierarchical layers, multiple parameters, and complex functional relations are especially susceptible to such variations. In this paper, we present a hierarchical method for process variation analysis. The ability to compute the variance of parameters at each hierarchical layer makes the method particularly suited for helping designers through design iterations. Experimental results indicate that the proposed method achieves high computational efficiency with up to 2% compromise in accuracy even for highly nonlinear functional relations.