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This paper describes a 4.5-Mb dynamic ternary CAM (DTCAM) which is suitable for networking applications. A dynamic TCAM cell structure in 130-nm embedded DRAM technology is used to realize the small cell size of 3.59 μm2. In addition, a novel array architecture of TCAM, the pipelined hierarchical searching (PHS) architecture, is proposed. The PHS architecture is found to be suitable for realizing small area penalty, high-throughput searching and low-voltage operation simultaneously. With the combination of the DTCAM cell and the PHS architecture, small silicon area of 32 mm2 for a fabricated 4.5-Mb DTCAM chip, high performance of 143 M searches per second and low power dissipation of 1.1 W have been achieved. To improve the yield of TCAMs, a novel shift redundancy technique is applied and estimated to result in 3.6-times yield improvement. These techniques and architectures described in this report are attractive for realizing cost-efficient, large-scale, high-performance TCAM chips.
Date of Publication: Jan. 2005