An energy efficient design of high-speed ternary CAM using match-line segmentation and resistive feedback in sense amplifier

Abstract — This paper presents a high-speed and low-energy match line (ML) sensing scheme for ternary content addressable memory (TCAM). The proposed sensing scheme employs selective precharge which performs partial comparison on the TCAM words to eliminate most of the mismatched words from further comparison. Use of positive feedback in the sense amplifiers engaged in this phase speeds up search operation and reduces energy consumption. In the next phase, remaining portions of those words which were matched in the first phase are scanned to find the fully matched words. Lower resistance in the charging path of the sense amplifier in the second phase causes fast match detection. The proposed technique is simulated using 130nm 1.2V CMOS logic. Compared to conventional current-race (CR) sensing scheme the proposed scheme shows 26.5 % speed enhancement and at least 31 % energy reduction at the cost of insignificant area overhead and small voltage margin degradation. Unlike many CR type schemes, no analog control voltage has been used in the proposed scheme. Index Terms — content-addressable memory, energy consumption, feedback, selective precharge, sense amplifier, sensing scheme, ternary I