Interconnect-aware low-power high-level synthesis

Abstract

Interconnects (wires, buffers, clock distribution networks, multiplexers, and busses) consume a significant fraction of total circuit power. In this paper, we demonstrate the importance of optimizing on-chip interconnects for power during high-level synthesis. We present a methodology to integrate interconnect power optimization into high-level synthesis. It not only reduces datapath unit power consumption in the resultant register-transfer level architecture, but also optimizes interconnects for power. We take into account physical design information and coupling capacitance to estimate interconnect power consumption accurately for deep submicron technologies. We show that there is significant spurious (i.e., unnecessary) switching activity in the interconnects and propose techniques to reduce it. Compared with interconnect-unaware power-optimized circuits, interconnect power can be reduced by 53.1% on average, while overall power is reduced by an average of 26.8%, with negligible area overhead. Compared with area-optimized circuits, the interconnect power reduction is 72.9% and overall power reduction is 56.0%, with 44.4% area overhead. The power reductions are obtained solely through switched capacitance reduction (no voltage scaling is assumed).