Variable pipeline structure for Coarse Grained Reconfigurable Array CMA

Cool mega-array (CMA) is a kind of coarse grained reconfigurable architecture (CGRA) which has shown its ability of ultra low-power computation. However, as CMA completely eliminates clock trees and registers, the performance improvement has been limited. In this paper, we introduce a variable pipeline structure to CMA with the minimum essential registers to provide more wide trade-off between performance and energy. Comparing with the baseline CMA (non-pipelined structure), an average of 77% improvement for performance was achieved with a small power overhead. Moreover, the energy efficiency was 1461 MOPS / mW at most which was about 2× that of the baseline structure. The best pipeline depth for an arbitrary energy-performance trade-off became selectable with only 11% area overhead.