Title :
A 126.6-mm2 AND-type 512-Mb flash memory with 1.8-V power supply
Author :
Ishii, Tatsuya ; Oshima, Kazuyoshi ; Sato, Hiroshi ; Noda, Satoshi ; Kishimoto, Jiro ; Kotani, Hiroaki ; Nozoe, Atsushi ; Furusawa, Kazunori ; Yoshitake, Takayuki ; Kato, Masataka ; Takahashi, Masahito ; Sato, Akihiko ; Kubono, Shoji ; Manita, Kiichi ; Ko
Author_Institution :
Device Dev. Center, Hitachi Ltd., Tokyo, Japan
fDate :
11/1/2001 12:00:00 AM
Abstract :
A 512-Mb flash memory, which is applicable to removable flash media of portable equipment such as audio players, has been developed. The chip is fabricated with a 0.18-μm CMOS process on a 126.6-mm2 die, and uses a multilevel technique (2 bit/1 cell). The memory cell is AND-type, which is suitable for multilevel operation. This paper reports new techniques adopted in the 512-Mb flash memory. First, techniques for low voltage operation are described. The charge pump, control of pumps, and the reference voltage generator are improved to generate internal voltage stably for multilevel flash memory. Next, a method for reducing total memory cost in the removable flash media is described. A new operation mode named read-modify-write is introduced on the chip. This feature makes the memory system simple, because the controller does not have to track sector-erase information
Keywords :
CMOS memory circuits; flash memories; low-power electronics; 1.8 V; 126.6 mm; 512 Mbit; AND-type flash memory; CMOS process; audio players; charge pump; control of pumps; low voltage operation; multilevel technique; portable equipment; read-modify-write mode; reduced total memory cost; reference voltage generator; removable flash media; stable internal voltage generation; CMOS process; Capacitors; Charge pumps; Circuits; Costs; Flash memory; Low voltage; Parasitic capacitance; Portable media players; Power supplies;
Journal_Title :
Solid-State Circuits, IEEE Journal of
