Improved Methods for Worst-Case Analysis and Optimization Incorporating Operating Tolerances

Worst-case analysis is commonly used in integrated circuit design to verify a satisfactory circuit performance with regard to changes in the manufacturing conditions. However, worst-case analysis is often carried out using approximate worst-case parameter sets, that do not consider fluctuations in the operating conditions. This paper presents a new approach to the worst-case design of integrated circuits that takes account of fluctuations in the operating conditions. It provides unique and realistic worst-case manufacturing conditions and worst-case operating conditions for given circuit specifications. These specifications may be either, minimum yield requirements or, lower and upper performance bounds. A software package for worst-case analysis and optimization is presented and illustrated by two examples.