Measuring constraint parameters at different combinations of circuit parameters

摘要

The value of a constraint parameter for a given combination of circuit parameters is estimated based on any prior computed values for other combinations of circuit parameters. As the estimate may be close to the actual value of the constraint parameter, a search may be performed (e.g., using simulation) in a narrow search range around the estimated value. As a result, the constraint parameters at different combinations of circuit parameters may be measured quickly. According to another aspect of the present invention, a curve is generated based on the results of multiple search points (with at least one point generating a pass result and another one point generating a fail result), and searches may be conducted between the pass and fail points by first checking whether the delay corresponding to intermediate points on the curve is lower than a desired threshold value.