Electronic Design

Instant "Replay" Comes To Timing Simulation

Many designers continue to perform timing simulation for gate-level designs. Through an add-on module for its Siloti Visibility Enhancement software, Novas Software now brings timing-accurate simulation replay capabilities to bear on the gate-level scenario.

Novas' Siloti Replay technology makes the process of detecting, isolating, and fixing the source of timing problems using gate-level simulation much more efficient, the company claims. The Siloti Replay module yields significantly faster simulation times and 10X smaller dump-file sizes when compared to traditional methods, while also providing the accuracy needed to debug timing issues that arise during chip implementation.

Timing simulation at gate level can augment static timing analysis, confirm gate-level engineering change orders (ECOs), and verify functional and structural tests that will be used to validate the actual silicon. The Siloti Replay module significantly reduces the signal data-recording requirements that can slow gate-level simulation to a crawl and eliminates the need to re-run long, costly simulations when errors are detected.

Gate-level timing simulation is notoriously slow, and capturing enough data for effective debugging only exacerbates the problem. Many design teams have adopted painful but necessary approaches in order to work around these issues. In doing so, they may limit timing simulations to only the most critical tests and pay the price of long, slow re-simulations to capture data when problems are detected. The Siloti Replay module addresses these issues by limiting the initial data dump to a relatively small set of essential signals, and by enabling fast, focused simulations to capture full signal data with timing for the time windows in which problems originate.

The Siloti SimVE visibility analysis engine is used to automatically derive the minimal set of "essential signals" required to drive the replay process. This serves to both accelerate the initial simulation and reduce the output dump file size. Users then perform an initial debug step to narrow the source of the problem in space (logic) and time, using the automated tracing capabilities available in the Novas Verdi Automated Debug System and applying the cycle-accurate SimVE data expansion capabilities to gain full visibility into the design.

The Siloti Replay module is then activated to run short, targeted simulations and capture timing-accurate signal data for the time windows of interest. These simulations can be run using any of today's popular simulators and are controlled through open application programming interfaces. Siloti Replay users realize significant efficiency gains because the follow-up simulation immediately jumps to the user-specified time window, eliminating the runtime usually spent getting to that point. These timing-accurate simulations can be performed multiple times for different time windows using the same baseline essential signal dump, and the results further analyzed and debugged with the Verdi system to better understand the cause-and-effect relationships and diagnose the root cause of timing problems.

The Siloti Replay module is immediately available as an add-on option to the Siloti SimVE product at the U.S. list price of $15,000 for an annual subscription license. The Siloti SimVE product starts at $25,000 U.S. Visit Novas Software.

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