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Seung-Moon YOO Ejaz HAQ Seung-Hoon LEE Yun-Ho CHOI Soo-IN CHO Nam-Soo KANG Daeje CHIN
Wide-voltage-range DRAM's with extended data retention are desirable for battery-operated or portable computers and consumer devices. This paper describes the techniques required to obtain wide operation, functionality, and performance of standard DRAM's from 1.8 V (2 NiCd or Alkaline batteries) to 3.6 V (upper end of LVTTL standard). Specific techniques shown are: 1) a low-power and low-voltage reference generator for detecting VCC level; 2) compensation of dc generators, VBB and VPP, for obtaining high speed at reduced voltages; 3) a static word-line driver and latch-isolation sense amplifier for reducing operating current; and 4) a programmable VCC variable self-refresh scheme for obtaining maximum data retention time over a full operating range. A sub-50-ns access time is obtained for a 16M DRAM(2M 8) by simulation.