A 65nm SRAM achieving 250mV retention and 350mV, 1MHz, 55fJ/bit access energy, with bit-interleaved radiation Soft Error tolerance

An Ultra Low Voltage memory was fabricated in 65nm CMOS with an optimized 10 transistors bitcell. It withstands 1.2V down to 0.35V voltage range, achieves 55fJ/bit energy access at 0.35V and exhibits wafer level yield above 95% at 0.4V, 1MHz. Packaged parts test show 0.32V minimum operating voltage at 500kHz, up to 17X energy gain per operation and 250mV retention voltage at 125°C. The memory terrestrial radiation Soft Error Rate was characterized with no multibit errors reported, enabling radiation reliability through bit-interleaving combined with error correcting code.