Low VMIN 20nm embedded SRAM with multi-voltage wordline control based read and write assist techniques

Abstract

Measured results of VMIN from 20nm SRAM arrays with read and write assist techniques are presented for multiple flavors of bitcell. A novel assist technique is presented, that provides both read and write assist by controlling only the voltage of wordline (WL) and without using a separate supply voltage. The WL-drivers use a WL float technique to reduce the dc-path current compared to existing WL under-drive read assist designs. The assist technique resulted in a VMIN improvement of 143mV for the high-density 6T (6T-HD) SRAM, 96mV for the high-speed 6T (6T-HS) SRAM, and 86mV for the 8T dual-port (DP) SRAM.