A Source Sensing Technique Applied to SRAM Cells

摘要

A new CMOS cell design is proposed, analyzed, and implemented in an ASIC macrocell generator to evaluate the performance and reliability of sensing the ground return current produced in the cell during read access. Both single and dual port cell configurations are studied for static noise margin (SNM), writing requirements, and source offset voltage effects. To frame the advantages and differences of the SSS cell, a comparison is made to several conventional SRAM cells. Noise margins are found to be the same or better than conventional cells, and where design allows cell device ratio optimizations, single ended access cells can generate greater SNM than differential cells. The source sensing technique was evaluated by inserting the new cell in a 0.5 μm ASIC memory block and tested on standard ASIC test sets.