Tertiary CAM cell

Abstract

A tertiary CAM cell with three bits of storage is disclosed. The three bits of storage are arranged to support three stable states which can be read from the CAM cell without requiring a charge restoration operation. The three stables states are those states where one of the three bits is at a first logical state while the remaining two bits are at a second logical state. The three stables states may be used to encode the three logical states used in a ternary CAM.

Description

[0001] This application claims the benefit of US Provisional Application No. 60 / 324462 (filed September 25, 2001), the contents of which are hereby incorporated by reference in their entirety. technical field [0002] The present invention relates generally to data semiconductor memory and, more particularly, to three levels of content addressable memory (CAM) cells. Background technique [0003] Many applications require high speed searching for information. In many network devices, such as switches or routers, data packets are transmitted based on the content of embedded address information. Therefore, in order to achieve high data transfer rates, network systems must be able to perform very high-speed searches and comparisons. One type of circuit useful for this function is content addressable memory, or CAM. It should be noted that while the discussion below is in the context of networked systems, there are many other applications that require high speed searching and ...

AI Technical Summary

Problems solved by technology

Unfortunately, CAM cell 400 is not suitable for use with a ternary CAM cell because a ternary CAM cell must be able to store at least three states

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