Content addressable memory having column redundancy
AssigneeNetLogic Microsystems, Inc.
InventorsVaradarajan Srinivasan, Bindiganavale S. Nataraj, Sandeep Khanna
Life of this patent
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Abstract
A content addressable memory (CAM) having a main array including a plurality of columns of CAM cells, a spare column of CAM cells selectable to functionally replace a defective column of CAM cells in the main array, a steering circuit for steering data corresponding to the defective column to the spare column, and a global mask circuit for masking the defective column during a compare operation.
Claims36
A content addressable memory (CAM), comprising:
- a main array including a plurality of columns of CAM cells;
- a spare column of CAM cells selectable to functionally replace a defective column of CAM cells in the main array;
- a steering circuit for steering data corresponding to the defective column to the spare column;
- and
- a global mask circuit for masking the defective column during a compare operation.
A content addressable memory (CAM) device, comprising:
- a main array including a plurality of columns of CAM cells;
- a spare column of CAM cells;
- and
- means for disabling a defective column of CAM cells in the main array without including fuses for the defective column.
A method for functionally replacing a defective column of content addressable memory (CAM) cells of a CAM array with a spare column of CAM cells, comprising:
- steering data corresponding to the defective column of CAM cells to the spare column of CAM;
- and
- masking the defective column during a compare operation.
A method for functionally replacing a defective column of content addressable memory (CAM) cells in a CAM array with a spare column of CAM cells, comprising:
- steering data corresponding to the defective column of CAM cells to a next column of CAM cells;
- steering data corresponding to each column subsequent to the defective column to an adjacent column of CAM cells;
- and
- steering data from a last column of CAM cells to the spare column of CAM cells.
Dependencies are inferred from the claim text.