Explicit and implicit X sources (X assignments in RTL and non-resettable flops, respectively) in the designs can lead to many challenging issues for design verification, such as masking real design errors and causing RTL-to-netlist simulation mismatches. Depending on coding styles, simulation results can be X-pessimistic which lead to unnecessary unknown values; or X-optimistic which results in known values when they should have been unknown. Design and verification teams write properties to trap Xs or instrument 2-value simulation with random initialization to avoid X ambiguity in order to detect design errors. However, these approaches take considerable amount of manual and computational resources without offering the complete confidence of X robustness.
Ascent PBV offers a multi-faceted solution that addresses the problem through structural and formal analysis, as well as by augmenting simulation using Ascent SimPortal. Explicit and implicit X sources are automatically detected. Innovative formal techniques are used to prove X-optimism safe designs. Ascent SimPortal can augment simulation to detect X-excitation, control X-pessimism, as well as eliminate X-optimism without loss of efficiency. It is the first automatic and comprehensive solution to detect and debug design errors and RTL/netlist simulation mismatches.
“Real Intent, as the leader in providing automatic functional verification solution for ASIC and FPGA designs, has been approached by many customers with issues related to X-handling in their designs,” commented Prakash Narain, President and CEO at Real Intent. “Ascent PBV meets the needs and rises to the challenges by using multiple innovative technologies to ensure X-robust designs. We deliver verification confidence to our customers by turning their verification unknowns into the known.”