Tri-state content addressable memory

Abstract

The invention discloses a ternary content addressable memory. The ternary content addressable memory comprises a search line connected with a ternary content addressable memory (TCAM) unit, the search line is provided with a booster circuit; the boost circuit comprises a metal wire which is arranged on one side of the search line and forms a coupling capacitor with the search line, and a boost control unit connected with the metal wire; when the search line is at a high level, the boost control unit sets the metal line to be at a high level; and the metal wire improves the voltage of the local search line at a high level through the coupling capacitance. The voltage of the search line can be further improved when the search line is at a high level, and after the voltage of the search line is improved, the VGS voltage of an NMOS tube for discharging the matching line in the TCAM unit can be increased, so that the discharge current can be increased, the discharge speed of the matching line can be increased, the evaluation speed of the matching line is increased, the search operation efficiency is improved, and the search efficiency is improved. And the working frequency and the performance of the ternary content addressable memory are further improved.

Description

technical field [0001] The present invention relates to tri-state content addressable memories. Background technique [0002] Ternary Content Addressable Memory (TCAM) is mainly used to quickly look up entries such as ACL and routing. It is developed on the basis of CAM. There are only two states of each bit in a general CAM memory, "0" or "1", while each bit in TCAM has three states, except for "0" and "1", there is also a "don" 't care' state, so it is called "three-state", it is realized by mask, it is this third state feature of TCAM that enables it to perform both exact match search and fuzzy match search, and CAM does not have a third state, so only exact match lookups are possible. [0003] The operating frequency of the TCAM depends on the speed of the search operation, and the core depends on the speed of the matching line ML discharge (that is, evaluation). Contents of the invention [0004] The purpose of the present invention is to provide a tri-state conten...

AI Technical Summary

Problems solved by technology

There are only two states of each bit in a general CAM memory, "0" or "1", while each bit in TCAM has three states, except for "0" and "1", there is also a "don" 't care' state, so it is called "three-state", it is realized by mask, it is this third state feature of TCAM that enables it to perform both exact match search and fuzzy match search, and CAM does not have a third state, so only exact match lookups can be performed

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