A current-recycling technique for shadow-match-line sensing in content-addressable memories

作者：Zhang Jian Wei^*; Ye Yi Zheng; Liu Bin Da

来源：IEEE Transactions on Very Large Scale Integration Systems, 2008, 16(6): 677-682.

DOI：10.1109/TVLSI.2008.2000247

• content-addressable memory (CAM)
• current-recycling
• low power
• shadow-match-line (SML) scheme

A current-recycling technique for shadow-match-line (SML) sensing in content-addressable memories (CAMS) is presented. In order to minimize energy-overhead, a novel current-recycling voltage detector (CRVD) is devised, whose working current is reused to charge up the match-line (ML) to determine matches or mismatches. Furthermore, with this CRVD, the word circuits realize fast-disable of the charging paths in case of mismatches. Since the majority of CAM words are mismatched, a significant power is reduced with a high search speed. Pre-layout simulation results show the proposed 256-word x 144-bit ternary CAM, based on a 0.13-mu m 1.2-V CMOS process, achieves 0.51 fJ/bit/search for the word circuit with less than 900-ps search time. The achievement illustrates a 74.2% energy-delay-product (EDP) reduction as compared with the speed-optimized current-saving scheme. Post-layout simulation results of the word circuits show 0.65 fJ/bit/search energy per search with 1.2-ns search time.

• 出版日期2008-6
• 单位哈尔滨工业大学