An Automatic Temperature Compensation of Internal Sense Ground for Subquarter Micron DRAM's

Tsukasa OOISHI  Yuichiro KOMIYA  Kei HAMADE  Mikio ASAKURA  Kenichi YASUDA  Kiyohiro FURUTANI  Hideto HIDAKA  Hiroshi MIYAMOTO  Hideyuki OZAKI  

IEICE TRANSACTIONS on Electronics   Vol.E78-C    No.6    pp.719-727
Publication Date: 1995/06/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on the 1994 VLSI Circuits Symposium (Joint Issue with the IEEE Journal of Solid-State Circuits, Vol. 30, No. 4 April 1995))

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This paper describes DRAM array driving techniques and the parameter scaling techniques for a low voltage operation using the boosted sense ground (BSG) scheme and further improved methods. A temperature compensation and adjustable internal voltage levels maintain a small subthreshold leakage current of a memory cell transistor (MC-Tr), and a distributed BSG (DBSG) scheme and a column decoded sensing (CDS) scheme achieve the effective scaling. These schemes can set the DRAM array free from a leakage current problem and free them from an influence of temperature variations. Therefore, parameters for the MC-Tr, threshold voltage (Vth), and the boosted voltage for the gate bias can be scaled down, and it is possible to determine the Vth of the MC-Tr easy (0.45 V at K = 0.4) for the satisfaction of the small leakage current, for the high speed and stable operation, and for the high reliability (VPP is below 2 VCC). They are applicable to the subquarter micron DRAM's of 256 Mb and more.