A Bitline Control Circuit Scheme and Redundancy Technique for High-Density Dynamic Content Addressable Memories

Tadato YAMAGATA  Masaaki MIHARA  Takeshi HAMAMOTO  Yasumitsu MURAI  Toshifumi KOBAYASHI  Michihiro YAMADA  Hideyuki OZAKI  

IEICE TRANSACTIONS on Electronics   Vol.E76-C   No.11   pp.1657-1664
Publication Date: 1993/11/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on LSI Memories)
Category: Application Specific Memory
content addressable memory,  associative memory,  dynamic memory,  redundancy,  

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This paper describes a bitline control circuit and redundancy technique for high-density dynamic content addressable memories (CAMs). The proposed bitline control circuit can efficiently manage a dynamic CAM cell accompanied by complex operations; that is, a refresh operation, a masked search operation, and partial writing, in addition to normal read/write/search operations. By adding a small supplementary circuit to the bitline control circuit, a circuit scheme with redundancy which prevents disabled column circuits from affecting a match operation can also be obtained. These circuit technologies achieve higher-density dynamic CAMs than conventional static CAMs. These technologies have been successfully applied to a 288-kbit CAM with a typical cycle time of 150 ns.