A 40nm fully functional SRAM with BL swing and WL pulse measurement scheme for eliminating a need for additional sensing tolerance margins

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 both depend on WLP width. 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.