PEAF: A Power-Efficient Architecture for SRAM-Based FPGAs Using Reconfigurable Hard Logic Design in Dark Silicon Era

Abstract

Significant increase of static power in nano-CMOS era and, subsequently, the end of Dennard scaling has put a Power Wall to further integration of CMOS technology in Field-Programmable Gate Arrays (FPGAs). An efficient solution to cope with this obstacle is power gating inactive fractions of a single die, resulting in Dark Silicon. Previous studies employing power gating on SRAM-based FPGAs have primarily focused on using large-input Look-up Tables (LUTs). The architectures proposed in such studies inherently suffer from poor logic utilization which limits the benefits of power gating techniques. This paper proposes a Power-Efficient Architecture for FPGAs (PEAF) based on combination of Reconfigurable Hard Logics (RHLs) and a small-input LUT. In the proposed architecture, we selectively turn off unused RHLs and/or LUTs within each logic block by employing a reconfigurable controller. By mapping a majority of logic functions to simple-design RHLs, PEAF is able to significantly improve power efficiency without deteriorating the performance. Experimental results over a comprehensive set of benchmarks (MCNC, IWLS'05, and VTR) demonstrate that compared with baseline four-LUT architecture, PEAF reduces the total static power and Power-Delay-Product (PDP), on average, by 24.5 and 21.7 percent, respectively. This is while the overall system performance is also improved by 1.8 percent. PEAF increases total area by 18.9 percent, however, it still occupies 22.1 percent less area footprint than the six-LUT architecture with 31.5 percent improvement in PDP.