Look-Ahead Dynamic Threshold Voltage Control Scheme for Improving Write Margin of SOI-7T-SRAM

Masaaki IIJIMA  Kayoko SETO  Masahiro NUMA  Akira TADA  Takashi IPPOSHI  

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E90-A   No.12   pp.2691-2694
Publication Date: 2007/12/01
Online ISSN: 1745-1337
DOI: 10.1093/ietfec/e90-a.12.2691
Print ISSN: 0916-8508
Type of Manuscript: Special Section LETTER (Special Section on VLSI Design and CAD Algorithms)
Category: Memory Design and Test
PD-SOI,  body-bias,  SRAM,  low power design,  

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Instability of SRAM memory cells derived from aggressive technology scaling has been recently one of the most significant issues. Although a 7T-SRAM cell with an area-tolerable separated read port improves read margins even at sub-1V, it unfortunately results in degradation of write margins. In order to assist the write operation, we address a new memory cell employing a look-ahead body-bias which dynamically controls the threshold voltage. Simulation results have shown improvement in both the write margins and access time without increasing the leakage power derived from the body-bias.