Static scheduling of multiple asynchronous domains for functional verification

While ASIC devices of a decade ago primarily contained synchronous circuitry triggered with a single clock, many contemporary architectures require multiple clocks that operate asynchronously to each other. This multi-clock domain behavior presents significant functional verification challenges for large parallel verification systems such as distributed parallel simulators and logic emulators. In particular, multiple asynchronous design clocks make it difficult to verify that design hold times are met during logic evaluation and causality along reconvergent fanout paths is preserved during signal communication. In this paper, we describe scheduling and synchronization techniques to maintain modeling fidelity for designs with multiple asynchronous clock domains that are mapped to parallel verification systems. It is shown that when our approach is applied to an FPGA-based logic emulator, evaluation fidelity is maintained and increased design evaluation performance can be achieved for large benchmark designs with multiple asynchronous clock domains.