Accelerating the SPICE Circuit Simulator Using an FPGA: A Case Study

Spatial processing of sparse, irregular, double-precision floating-point computation using a single FPGA enables up to an order of magnitude speedup and energy-savings over a conventional microprocessor for the simulation program with integrated circuit emphasis (SPICE) circuit simulator. We develop a parallel, FPGA-based, heterogeneous architecture customized for accelerating the SPICE simulator to deliver this speedup. To properly parallelize the complete simulator, we decompose SPICE into its three constituent phases—Model Evaluation, Sparse Matrix-Solve, and Iteration Control—and customize a spatial architecture for each phase independently. Our heterogeneous FPGA organization mixes very large instruction word (VLIW), Dataflow and Streaming architectures into a cohesive, unified design. We program this parallel architecture with a high-level, domain-specific framework that identifies, exposes and exploits parallelism available in the SPICE circuit simulator using streaming (SCORE framework), data-parallel (Verilog-AMS models) and dataflow (KLU matrix solver) patterns. Our FPGA architecture is able to outperform conventional processors due to a combination of factors including high utilization of statically-scheduled resources, low-overhead dataflow scheduling of fine-grained tasks, and streaming, overlapped processing of the control algorithms. We expect approaches based on exploiting spatial parallelism to become important as frequency scaling continues to slow down and modern processing architectures turn to parallelism (e.g. multi-core, GPUs) due to constraints of power consumption.