A 0.4V 7T SRAM with write through virtual ground and ultra-fine grain power gating switches

This paper presents a 7T near-threshold SRAM with design techniques for improving cell stability and energy efficiency. The proposed write through virtual ground (WTVG) scheme decreases the period of write disturbance by 6.1×. A PVT tracking sensing scheme is presented to track variation and sense small RBL swing. The ultra-fine grain power gating switches are implemented to minimize the redundant leakage caused by the storage of garbage data. The leakage suppression of 52% is achieved after the initial power-up. A 16 kb SRAM test chip was fabricated in a 65nm CMOS technology and showed the minimum energy of 2.01 pJ at 0.4 V.