Ultra low power litho friendly local assist circuitry for variability resilient 8T SRAM

This paper presents litho friendly circuit techniques for variability resilient low power 8T SRAM. The new local assist circuitry achieves a state-of-the-art low energy and variability resilient WRITE operation and improves the degraded access speed of SRAM cells at low voltages. Differential VSS bias increases the variability resilience. The physical regularity in the layout of local assist circuitry enables litho optimization thereby reducing the area overhead associated with existing local assist techniques. Statistical simulations in 40nm LP CMOS technology reveals 10x reduction in WRITE energy consumption, 10³x reduction in write failures, 6.5x improvement in read access time and 31% reduction in the area overhead.