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AR# 34925: XPA - Why would my simulation nets not match 100%?
XPA - Why would my simulation nets not match 100%?
Why would my simulation nets not match 100%?
There can be multiple reasons why the simulation data does not match.
The simulation file is incomplete; it does not contain activity information for all the nets.
The net names in the simulation file does not match the actual physical net names after routing. For example, if simulation was done on RTL netlist, then the net names in simulation file can be different from those after routing.
Simulation was performed on a subset of the design. The simulation might have been run on a sub module of a design. Therefore, activity for the top level and other portion of the design is not defined in the simulation file. Providing activity for a subset of the entire design is better than not providing any simulation input. (Assuming the simulation data represent realistic typical or worst case design activity.)
The behavioral simulation results were provided. Pre-implementation behavioral (RTL) simulation results are more often available than post-implementation (timing) simulation results in part because such simulation run faster. Since the design file contains post-implementation information, there most likely were transformation in the design during implementation which changed net name and signal connectivity; hence, preventing the matching. Providing activity from a behavioral activity file is better than not providing any simulation input. (Assuming the simulation data represent realistic typical or worst case design activity.)
Hierarchy separator mismatch. Ensure hierarchy separator match between your synthesis tool, post implementation simulation netlist, and the simulation tool. For instance, some tools might use _ while others /.