Hiroshi Fuketa Masanori Hashimoto Yukio Mitsuyama Takao Onoye Correlation verification between transistor variability model with body biasing and ring oscillation frequency in 90nm subthreshold circuits. 3-8 2008 ISLPED http://doi.acm.org/10.1145/1393921.1393929 conf/islped/2008 db/conf/islped/islped2008.html#FuketaHMO08