Energy Optimized Subthreshold VLSI Logic Family With Unbalanced Pull-Up/Down Network and Inverse Narrow-Width Techniques

Ultralow-energy biomedical applications have urged the development of a subthreshold VLSI logic family in standard CMOS. This brief proposes an unbalanced pull-up/down network, together with an inverse narrow-width technique, to improve the operating speed of the individual logic cell. Effective logical efforts save both power and die area in the process of device sizing and topology optimization. Three experimental 14-tap 8-bit finite impulse response filters optimized for ultralow-voltage operation were fabricated in 0.18-μm CMOS. Measurements show that the optimized 0.45 and 0.6 V libraries achieve minimum energy operations at 100 kHz, with a figure-of-merit of 0.365 (at 0.31 V) and 0.4632 (at 0.39 V), respectively. They correspond to 35.96% and 18.74% improvements, and the overall performances are well comparable with the state of the art.