A 0.32V, 55fJ per bit access energy, CMOS 65nm bit-interleaved SRAM with radiation Soft Error tolerance

A 32kb memory is presented with an Ultra Low Voltage optimized 10 transistors bitcell designed to withstand an extended voltage range from 1.2V down to 0.35V, achieving 1.77pJ low energy access. A validation circuit was fabricated in 65nm CMOS and exhibits wafer level yield above 95% at 0.4V, 1MHz. Packaged parts show 0.32V minimum voltage at 490kHz and up to 17X energy gain per operation. The memory terrestrial radiation Soft Error Rate was characterized with no multibit errors reported, enabling future medical appplications radiation reliability through bit-interleaving combined with error correcting code.