Content addressable memory storage device

Abstract

Binary and ternary content addressable memory (CAM) cells are disclosed, which permit the construction of high-performance, large-capacity CAM arrays. The CAM cells have a reduced match line power dissipation, and a reduced compare line loading that is data independent, and full swing comparator output. Match line power dissipation is limited by means of a NAND chain match line. Loading on compare lines is limited by connecting compare lines to the gate terminals of the CAM cell comparator. Local precharge devices at the output of the comparator provide full swing compare logic levels for faster matching. The same precharge devices also serve as an active reset for the comparator. Comparator circuits for ternary CAM cells further employ disable means, which makes the comparison operation conditional on the value stored in the mask memory element. The use of disable means allows the mask and data to be stored separately in a non-encoded form. As a result, mask and data information may be read and written independently of one another.