A 4-Mb SRAM Using a New Hierarchical Bit Line Organization Utilizing a T-Shaped Bit Line for a Small Sized Die

Yoshiyuki HARAGUCHI  Toshihiko HIROSE  Motomu UKITA  Tomohisa WADA  Masanao EINO  Minoru SAITO  Michihiro YAMADA  Akihiko YASUOKA  

IEICE TRANSACTIONS on Electronics   Vol.E79-C   No.6   pp.743-749
Publication Date: 1996/06/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on ULSI Memory Technology)
Category: Static RAMs
integrated electronics,  high density SRAM,  hierarchical bit line organization,  T-shaged bit line,  

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This paper describes a new hierarchical bit line organization utilizing a T-shaped bit line(H-BLT) and its practical implementation in a 4-Mb SRAM using a 0.4µm CMOS process. The H-BLT has reduced the number of I/O circuits for multiplexers, sense amplifiers and write drivers, resulting in an efficient multiple blockdivision of the memory cell array. The size of the SRAM die was reduced by 14% without an access penalty. The active current is 30mA at 5 V and 10 MHz. The typical address access time is 35 ns with a 4.5 V supply voltage and a 30 pF load capacitance. The operating voltage range is 2.5 V to 6.0 V. H-BLT is a bright and useful architecture for the high density SRAMs of the future.