OR type cascade ML structure

Abstract

The invention relates to an ML (Match Line) structure, in particular to an OR type cascade ML structure, which consists of first, second to n-th single-stage OR type ML circuits through cascade connection in series, wherein each single-stage OR type ML circuit comprises a comparison control module, a sensitive amplifier and first, second to n-th TCAM units; each comparison control module is connected with the corresponding sensitive amplifier through an ML; and each of the first, second to n-th TCAM units is connected with the ML in parallel. Most searching operations are mismatched in the first stage, the later-stage searching operations do not need to be started; the correlation between the single-stage ML power consumption and the TCAM unit number is small, so that the integral circuit ML average power consumption cannot be increased due to the increase of the work circuit bit number; meanwhile, the resetting operation on a search line is not needed by the ML structure; and the power consumption reduction of the search line is facilitated.

Description

technical field [0001] The present invention relates to a matching line structure, more specifically, to an OR-type cascaded matching line structure. Background technique [0002] In the past, many researchers have focused on reducing the power consumption of TCAM match lines without sacrificing speed. References [1] Jian-WeiZhang, Yi-ZhengYe, and Bin-DaLiu, "ACurrent-RecyclingTechniqueforShadow-Match-LineSensinginContent-AddressableMemories," IEEETRANSACTIONSONVERYLARGESCALEINTEGRATION(VLSI)SYSTEMS,VOL.16,NO.6,pp.677-6202,JUNE The author in . proposes a lower match line scheme based on charge reuse CAM, which simultaneously achieves the requirements of high speed and low power consumption. However, its internal level shifter uses a charge pump, causing the sensitive amplifier to be particularly sensitive to the lower match line. Since the TCAM chip performs a parallel search operation, each search operation will generate a large amount of noise, which will be coupled to t...

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Problems solved by technology

But in the pre-charging stage, the match line structure needs to reset the search line to disconnect the upper match line and the lower match line, so the search line consumes a lot of power

At the same time, since each section of the circuit is connected in parallel, the matching results of each section need to be connected to the final evaluation circuit, which will cause long connection lines and increase the search delay when the layout is realized.

Many researchers have devoted themselves to dividing word circuits into several segments and cascading them in series, for example, reference [6] Jianwei, Zhang, et al. "Acascaded charge-sharing technique for an EDP-efficient match-line design in CAMs." Journal of Semiconductors 30.6 (2009): 065009. However, these solutions have problems such as high power consumption and complicated connection lines.

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