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Silicon Valley SNUG: Sub-cycle Functional Timing Verification Using SystemVerilog Assertions

Verilab’s Anders Nordstrom will be presenting his paper “Sub-cycle Functional Timing Verification using SystemVerilog Assertions” at the Tuesday March 26th session at 10:30 am of SNUG Silicon Valley 2013.

This presentation shows a novel, more complete approach to functional verification of sub-cycle timing using SystemVerilog assertions in an OVM verification environment. This approach found many bugs which otherwise were missed in OVM-only simulations that didn’t include assertions.

This functional sub-cycle timing behaviour includes maintaining fixed delays and phase relationships between inputs and outputs and ensuring there are no glitches on clocks or delayed signals.

SystemVerilog assertions are evaluated on successive occurrences of an event or timing expression. This presents a challenge for sub-cycle timing verification, where there is no obvious reference clock suitable for triggering the assertions. Assertions sample their expressions in the preponed region of the simulation timestep, but the requirements called for sampling both before and after each triggering point. Examples of assertions showing how to overcome this and many other issues will be shown along with recommendations on how to write assertions for functional timing verification.

This paper is complementary to the paper presented by Paul Marriott at DVCon 2013 entitled Run-time Configuration of a Verification Environment - A Novel Use of the OVM/UVM Analysis Pattern. The sub-cycle timing relationships were dynamically varied during simulation and the assertions used were required to check for correctness as the actual relationships varied during the simulation.

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