Worst case tolerance analysis of linear analog circuits using sensitivity bands

The major difficulty of accurate worst case tolerance analysis is to identify the worst case parameter sets. Traditional vertex analysis presumes the monotonicity between circuit response and circuit parameters, and uses nominal sensitivity information to select the vertices of parameter space as the worst case parameter sets. However, under parameter variations, the sensitivity itself is uncertain within an interval range, furthermore, the worst case parameter sets may not be the vertices of parameter space. In this paper, the relationship among monotonicity, sensitivity, and worst case parameter sets is investigated in the context of parameter variations. An efficient yet accurate approach for linear circuit worst case tolerance analysis is proposed. The underlying idea is that if the circuit response is monotonic with respect to the changes in a specific circuit parameter over the parameter space, then the worst case parameter sets are located at the corners of that parameter. The monotonicity is identified by the sensitivity band computation, and is used to generate uncertainty-reduced simulation problems. Experimental results strongly meet the expectation for accuracy and efficiency.