US Patent 7181713 Static timing and risk analysis tool

A system and method for evaluating multiple corner case static timing analyses. For each node within the analysis, the variability and margin of the node is used to create a risk factor that is used to identify nodes for further analysis. In some cases, a subset of nodes may be selected for static timing analysis with several additional corner cases. The variability of the node may be determined by the difference between the maximum and minimum value of the node between corner case analyses. The margin may be determined by the difference between the actual timing and the required timing. Various ratios using variability and margin may be used to identify those nodes on which to perform further analysis.