Power-gating-aware high-level synthesis

A problem inherent in designing power-gated circuits is the overhead of the state-retention storage required to preserve the circuit state in standby mode. Reducing the amount of retention storage is known to be the most influential factor in minimizing the loss of the benefit (i.e. power saving) by power-gating. In this paper, we address a new problem of high-level synthesis with the objective of minimizing the size of retention storage to be used in the power-gated circuits. Specifically, we propose a complete design framework, called HLS-pg, that starts from the power-gating-aware scheduling, allocation, and controller synthesis down to the final circuit layout. The key contribution of the work is to solve the power-gating-aware scheduling problem, namely, scheduling operations that minimizes the number of retention registers required at the power-gating control step, while satisfying resource and latency constraints. In experiments on benchmark designs implemented in 65-nm CMOS technology, HLS-pg generates circuits with 27% less leakage current, with 6% less circuit area and wirelength, compared to the power-gated circuits produced by conventional high-level synthesis.