Session 7-1

A 40nm Fully Functional SRAM with BL Swing
and WL Pulse Measurement Scheme
for Eliminating a Need for Additional Sensing Tolerance Margins

 

Abstract

A method for direct measurements of bit-line (BL) swing, sense amplifier (SA) offset and word-line (WL) pulse width is demonstrated in a 40nm CMOS 32kb fully functional SRAM macro with <2% area penalty. This allows, for the first time, deciding the best tuning option for WL-pulse (WLP) width based on the results being measured on site for BL swing and dynamic read/write stability (DRWS), which depend on WLP width, as well. It has enabled to eliminate a need of additional margin for BL swing, which was conventionally needed for ensuring tolerance against its simulation errors and inaccurate SA-offset estimation. As a result, it was found that more aggressive option for WLP width could be chosen while ensuring the target BL swing.