Content addressable memory device

A ternary content addressable memory (TCAM) device comprising:

• A plurality of TCAM cells for storing data, each TCAM cell having two memory cells and a comparison circuit for comparing data stored in the memory cells with data input on a search line pair connected to the comparison circuit, wherein the comparison circuit comprises first, second, third, and forth NMOS transistors, the first and second NMOS transistors having their drains connected to a match line, their gates connected to the memory cells and their source connected to drains of the third and forth NMOS transistors, and the third and forth NMOS transistors having their gates connected to the search line pair and their source connected to ground, further including redundant TCAM cells and a switching circuit for switching at least a plurality of connections of TCAM cells determined to be defective to corresponding connections of the redundant TCAM cells.

A ternary content addressable memory (TCAM) device comprising:

• A plurality of TCAM cells for storing data, each TCAM cell having two memory cells and a comparison circuit for comparing between data stored in the memory cells and data input on a search line pair connected to the comparison circuit, wherein the comparison circuit comprises a first plurality of MOS transistors connected between a match line and a second plurality of MOS transistors, the second plurality of MOS transistors being connected to ground, wherein the first plurality of MOS transistors are gated by signals from the memory cells connected thereto and the second plurality of transistors are gated by signals from a search line pair, further including a main search line driver for driving data signals to a plurality of search line pairs and at least one redundant search line driver for replacing the main search line driver upon determination that at least one of the memory cells connected to a corresponding search line pair is defective.

A ternary content addressable memory (TCAM) device comprising:

• A plurality of TCAM cells for storing data, each TCAM cell having two memory cells and a comparison circuit for comparing between data stored in the memory cells and data input on a search line pair connected to the comparison circuit, wherein the comparison circuit comprises a first plurality of MOS transistors connected between a match line and a second plurality of MOS transistors, the second plurality of MOS transistors being connected to ground, wherein the first plurality of MOS transistors are gated by signals from the memory cells connected thereto and the second plurality of transistors are gated by signals from a search line pair, further including redundant TCAM cells and a switching circuit for switching at least a plurality of connections of TCAM cells determined to be defective to the redundant TCAM cells.

A method of operating a ternary content addressable memory (TCAM) device comprising:

• comparing data stored in memory cells of the TCAM with data input on a search line pair connected to a comparison circuit, wherein the comparison circuit comprises a first plurality of MOS transistors connected between a match line and a second plurality of MOS transistors, the second plurality of MOS transistors being connected to ground, wherein the first plurality of MOS transistors are gated by signals from the memory cells connected thereto and the second plurality of transistors are gated by signals from a search line pair, further including switching at least a plurality of connections of TCAM cells determined to be defective to redundant TCAM cells.