Offset-Compensated Direct Sensing and Charge-Recycled Precharge Schemes for Sub-1.0 V High-Speed DRAM's

Jae-Yoon SIM  Kee-Won KWON  Ki-Chul CHUN  Dong-Il SEO  

Publication
IEICE TRANSACTIONS on Electronics   Vol.E87-C   No.5   pp.801-808
Publication Date: 2004/05/01
Online ISSN: 
DOI: 
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Integrated Electronics
Keyword: 
low voltage DRAM,  sensing,  precharge,  offset compensation,  charge-recycling,  

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Summary: 
This paper proposes a sensing and a precharge circuit schemes suitable for low-voltage and high-speed DRAM design. The proposed offset-compensated direct sensing scheme improves refresh characteristics as well as speed performance. To minimize the number of control switches for the offset compensation, only the output branches of differential amplifiers are implemented in each bit-line pair with a semi-global bias branch, which also reduces 50-percent of bias current. The addition of the direct sensing feature to the offset-compensated pre-sensing dramatically increases the differential current output. For the fast bit-line equalization, a charge-recycled precharge scheme is proposed to reuse VPP discharging current for the generation of a boosted bias without additional charge pumping. The two circuit schemes were verified by the implementation of a 256 Mb SDRAM with a 0.1 µm dual-doped poly-silicon technology.