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

Abstract

The minimum operating voltage (V min) of every cell on a 32 kb fully depleted SOI static random-access memory (SRAM) macro is successfully measured. Competing V min distribution models, which include the gamma and log-normal distributions, are approximated using the generalized gamma distribution. It is found that the V min of the cells follows the gamma distribution. This finding gives a simple method to estimate the worst V min of an SRAM macro by measuring a few samples and performing linear extrapolation from the gamma distribution.