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

Contention-less flip-flops (CLFF's) and separated power supply voltages (V
_DD
) 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 V
_DD
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.