Estimation of minimum operating voltage in fully depleted SOI SRAM cells using gamma distribution

Abstract

Abstract Minimum operating voltages (Vmin) of every cell on a 32kb fully-depleted (FD) SOI static random access memory (SRAM) macro are successfully measured. The competing Vmin distribution models, which include the gamma and log-normal distribution, are approximated using the generalized gamma distribution (GENG). It is found that Vmin of the cells follow the gamma distribution. This finding gives a simple method to estimate worst Vmin of an SRAM macro by measuring few samples and make linear extrapolation from the gamma distribution.