A 21-mW 4-Mb CMOS SRAM for battery operation. - Shuji Murakami; Kore-aki Fujita; Motomu Ukita; Kazuhito Tsutsumi; Yasuo Inoue; Osamu Sakamoto; Motoi Ashida; Yasumasa Nishimura; Yoshio Kohno; Tadashi Nishimura; Kenji Anami (IEEE J. Solid State Circuits, 1991)