Title :
A 4-Mb pseudo SRAM operating at 2.6±1 V with 3-μA data retention current
Author :
Sato, Katsuyuki ; Kenmizaki, Kanehide ; Kubono, Shoji ; Mochizuki, Toshio ; Aoyagi, Hidetomo ; Kanamitsu, Michitaro ; Kunito, Soichi ; Uchida, Hiroyuki ; Yasu, Yoshihiko ; Ogishima, Atsushi ; Sano, Sho ; Kawamoto, Hiroshi
Author_Institution :
Hitachi Ltd., Tokyo, Japan
fDate :
11/1/1991 12:00:00 AM
Abstract :
A 4-Mb pseudo static RAM (PSRAM) suitable for universal battery usage is described. The wide voltage range, 2.6±1 V, is set to target the power supply voltage of the PSRAM considering various voltage levels and charging-discharging characteristics of batteries. A double-to-single automatically switchable booster is developed to provide the wide voltage range operation. To reduce the power dissipation of data retention for battery usage a low-power back-bias generator with a new substrate-level sensor and a temperature-dependent self-refresh timer with a unique internal refresh control scheme are demonstrated. A PSRAM operation ranging from 1 V to more than 5 V was obtained and a 3-μA data retention current was realized at room temperature in contrast with 7 μA at 70°C and Vcc of 2.6 V. This PSRAM allows a 20-Mbyte RAM disk to retain data for two months with a single lithium battery
Keywords :
SRAM chips; 1 to 5 V; 2.6 V; 20 Mbyte; 3 muA; 4 Mbit; RAM disk; automatically switchable booster; charging-discharging characteristics; data retention; data retention current; internal refresh control scheme; low-power back-bias generator; memory IC; power dissipation; pseudo SRAM; static RAM; substrate-level sensor; temperature-dependent self-refresh timer; universal battery usage; wide voltage range operation; Automatic generation control; Batteries; Power dissipation; Power generation; Power supplies; Random access memory; Sensor phenomena and characterization; Temperature control; Temperature sensors; Voltage;
Journal_Title :
Solid-State Circuits, IEEE Journal of
