Time-Division Multiplexing Based System-Level FPGA Routing

Abstract

Multi-FPGA system prototyping has become popular for modern VLSI logic verification, but such a system realization is often limited by its number of inter-FPGA connections. As a result, time-division multiplexing (TDM) is employed to accommodate more inter-FPGA signals than the connections in a multi-FPGA system. However, the inter-FPGA signal delay induced by TDM becomes significant due to time-multiplexing. Researchers have shown that TDM ratios (signal time-multiplexing ratios) significantly affect the performance of a multi-FPGA system and inter-FPGA routing highly influences the quality of this system. This paper presents a framework to minimize the system clock period for a system-level FPGA while considering the inter-FPGA routing topology and the timing criticality of nets. Our framework consists of two stages: (1) a distributed profiling scheme to generate the desired net-ordering and then alleviate the routing congestion, and (2) a net-/edge-based refinement to assign TDM ratios efficiently with a strict decrease in the ratios. Based on the 2019 CAD contest at ICCAD benchmarks and the contest evaluation metric with both quality and efficiency, experimental results show that our framework achieves the best overall score among all the participating teams and published works.