12.7-times energy efficiency increase of 16-bit integer unit by power supply voltage (VDD) scaling from 1.2V to 310mV enabled by contention-less flip-flops (CLFF) and separated VDD between flip-flops and combinational logics

Abstract

Contention-less flip-flops (CLFF's) and separated power supply voltages (VDD) between flip-flops (FF's) and combinational logics are proposed to achieve a maximum energy efficiency operation. The proposed technologies were applied to a 16-bit integer unit (IU) for media processing in a 65-nm CMOS process. Measurement results of fabricated chips show that the proposed CLFF reduces the minimum operating voltage of IU's by 64mV on average. By scaling VDD from 1.2V to 310mV with the proposed CLFF, the maximum energy efficiency of 1835GOPS/W and the highest energy efficiency increase of 12.7 times are achieved.