Abstract: A computer executable processing component analyzes unknown (X) propagation from uninitialized latches in gate-level simulation and determines if the Xs cause false Xs to be generated due to X-pessimism. For Xs generated due to X-pessimism, simulation results are corrected and fixes are generated. Corrected simulation results match real hardware behavior and greatly reduces engineers' analysis effort on debugging X issues. A computer executable processing component analyzes unknown (X) propagation from sequential cells in gate-level logic simulation and determines if the Xs cause false Xs to be generated due to X-pessimism. For Xs generated due to X-pessimism, simulation results are corrected and fixes are generated. Corrected simulation results match real hardware behavior and greatly reduces engineers' analysis effort on debugging X issues.

Abstract: A computer executable tool analyzes unknowns (Xs) in gate-level simulation and traces their sources to determine if the Xs are generated due to X-pessimism. For Xs generated due to X-pessimism, fixes are generated to correct simulation results. Corrected simulation results match real hardware behavior and greatly reduce the analysis effort of engineers.

Abstract: A retention synthesis application provides a means of analyzing a circuit design, functional test sequences, and the associated power specification to identify registers that do not need retention when a block is powered down. Reducing the number of retention registers reduces power consumption and chip area. The retention synthesis application is based, at least in part, upon symbolic simulation. In symbolic simulation, a symbol is used to represent a value that can be either 0 or 1 and the propagation of symbols is traced through the simulation.

Abstract: A digital circuit simulation method and apparatus provide for critical path timing analysis of digital circuitry using a hybrid path tracing method. The hybrid path tracing performs path tracing when, for example, simulation values change at designated inputs. The path tracing can employ the simulation values for eliminating blocked paths. During tracing, the method and apparatus determine the shortest and longest paths from each input or beginning point to each end point. The end points are typically storage elements such as latches, flip-flops or systems outputs at a high functional level. The critical path tracing analysis finds the shortest and longest paths from the beginning point to the end point and records and saves the violation history, if any, associated with those paths. A timing template allows the user to develop the necessary input stimuli, in a logical ordered format to test the timing behavior of the digital circuit to be designed.