A 55nm 0.55v 6T SRAM with variation-tolerant dual-tracking word-line under-drive and data-aware write-assist

We present a 55nm 128Kb 6T SRAM with a variation-tolerant dual-tracking Word-Line Under-Drive (WLUD) to improve the RSNM and a Data-Aware Write-Assist (DAWA) scheme. Error free full functionality without redundancy is achieved from 1.5V down to 0.55V with area overhead of 4% for WLUD and 14% for DAWA, respectively. The measured power overheads (FF, 25oC) are 1.1% for WLUD and 3.3% for DAWA at 1.0V (3% and 5.3% at 0.6V), respectively. The maximum operating frequency is 940MHz (360MHz) at 1.0V (0.6V) and 25oC. The measured power/performance (FF, 25oC) is 0.117mW/MHz (0.023mW/MHz) at 1.0V (0.6V).