Sleep Mode Analysis and Optimization With Minimal-Sized Power Gating Switch for Ultra-Low ${V}_{\rm dd}$ Operation

This paper investigates the optimization of sleep mode energy consumption for ultra-low V_dd CMOS circuits, which is motivated by our findings that minimization of sleep mode energy holds great potential for reducing total energy consumption. We propose a unique approach of using a power gating switch (PGS) in ultra-low V_dd regimes. Unlike the conventional manner of using PGSs, our optimization suggests using minimal-sized PGSs with a slightly higher V_dd to compensate for voltage drop across the PGS. In SPICE simulations, this reduces total energy consumption by ~125× compared to conventional approaches. The effectiveness of the proposed optimization is also confirmed by measurements taken from an ultra-low power microprocessor. Additionally, the feasibility of using minimal PGSs in ultra-low V_dd regimes is investigated using SPICE simulations and silicon measurements.