Chi D Bui

US Patent:

6564344, May 13, 2003

Filed:

Nov 8, 1999

Appl. No.:

09/435866

Inventors:

Chi Duy Bui - Austin TX
Manoj Kumar - Santa Clara CA
Terry Lee Leasure - Georgetown TX

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G11C 2900

US Classification:

714718, 365201

Abstract:

Each match word line driver circuit associated with a content addressable memory (CAM) utilizes a scannable latch for testing. The scannable latches associated with a particular CAM are connected together, scan output of one to scan input of the next, forming a scanning latch chain. In test mode the scannable dynamic latch is used either for testing CAM match circuits or for driving word lines to test the RAM array. Testing CAM match circuits is accomplished by patterning the CAM array with known storage values. The match circuitry then compares an effective address to each storage value and the results are scanned out. Testing the RAM array is performed by driving each word line with a known scan value. Each word line responds the scan value and a sense amplifier outputs a RAM array value based on the word line.