Title :
A 4-Mb CMOS SRAM with a PMOS thin-film-transistor load cell
Author :
Ootani, Takayuki ; Hayakawa, Shigeyuki ; Kakumu, Masakazu ; Aona, A. ; Kinugawa, Masaaki ; Takeuchi, Hideki ; Noguchi, Kazuhiro ; Yabe, Tomoaki ; Sato, Katsuhiko ; Maeguchi, Kenji ; Ochii, Kiyofumi
Author_Institution :
Toshiba Corp., Kawasaki, Japan
fDate :
10/1/1990 12:00:00 AM
Abstract :
A 4-Mb (512 K words by 8-b) CMOS static RAM (SRAM) with a PMOS thin-film transistor (TFT) has been developed. The RAM can obtain a much larger data-retention margin than a conventional high-resistive load-type well by using the PMOS TFT as a memory cell load. An internal voltage down-converter architecture with an external supply voltage-level sensor not only realizes a highly reliable 0.5-μm MOS transistor operation but also a sufficiently low standby-power dissipation characteristic for data battery-backup application. A self-aligned equalized level sensing scheme can minimize the sensing delay for a local sense amplifier to drive a large load capacitance of a global sensing bus line. The RAM is fabricated using a 0.5 μm, triple-poly, and double-aluminum with dual gate-oxide-thickness CMOS process technology. The RAM operates under a single 5-V supply voltage with 23-ns typical address access time and 20- and 70-mA operation current at 10 and 40 MHz, respectively
Keywords :
CMOS integrated circuits; SRAM chips; thin film transistors; 0.5 micron; 10 MHz; 20 mA; 23 ns; 4 Mbit; 40 MHz; 5 V; 70 mA; CMOS SRAM; PMOS thin-film-transistor; Si; TFT load cell; address access time; data battery-backup application; double Al metallisation; dual gate-oxide-thickness CMOS process; external supply voltage-level sensor; internal voltage down-converter architecture; low standby-power dissipation characteristic; memory cell load; self-aligned equalized level sensing scheme; static RAM; triple-poly; CMOS process; CMOS technology; Capacitance; Delay; MOSFETs; Random access memory; Read-write memory; Sensor phenomena and characterization; Thin film transistors; Voltage;
Journal_Title :
Solid-State Circuits, IEEE Journal of
