Dual-period self-refresh scheme for low-power DRAM's with on-chip PROM mode register. - Youji Idei; Katsuhiro Shimohigashi; Masakazu Aoki; Hiromasa Noda; Hidetoshi Iwai; Katsuyuki Sato; Tadashi Tachibana (IEEE J. Solid State Circuits, 1998)