Questa CDC identifies errors to do with Clock-Domain Crossings (CDC) – signals (or groups of signals) that are generated in one clock-domain and consumed in another. It does so with structural analysis and recognition of clock-domains, synchronizers, and low power structures (via UPF); and with generation of metastability models for reconvergence verification.

Introducing Questa CDC

Designers increasingly use advanced multi-clock architectures to meet the high-performance and low-power requirements of their chips. An RTL or gate-level simulation of a design that has more than one clock domain does not accurately model the silicon behavior related to the transfer of data between asynchronous clock domains. As a consequence, simulation does not accurately predict silicon functionality, risking show-stopper bug escapes.

The technology exhaustively checks all potential CDC failures, statically verifying that all signals crossing asynchronous clock domain boundaries are guarded by CDC synchronizers. It then illustrates DUT issues found with familiar schematic and waveform displays. Additionally, in concert with Questa simulation, the CDC-FX app injects metastability into RTL functional simulation to verify the DUT is tolerant of random delays caused by metastability.

Automated assertion generation and analysis

Using only your RTL and UPF power intent file, Questa CDC solutions automatically generate and analyze assertions to rapidly identify chip-killing clock-domain crossing issues.

Industry-leading scalability and QoR

When analysing billion-gate designs, minimizing “noise” is critical. Questa CDC comprehensive, hierarchical, formal-based analysis searches through DUT elements for high throughput and noise minimization, simultaneously providing industry-leading scalability and high quality of results, while enabling CDC IP reuse.

Ease of set-up and use

Questa CDC supports the Synthesis Design Constraints (SDC) format for clock- and port- domain settings, and it includes a TCL scripting environment with powerful control and reporting capabilities. Questa CDC automatically identifies your clocks and clock distribution strategy minimizing set-up time.