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Issue No. 11 - Nov. (2012 vol. 61)
ISSN: 0018-9340
pp: 1576-1587
Jin-Fu Li , Dept. of Electr. Eng., Nat. Central Univ., Jhongli, Taiwan
ABSTRACT
Ternary content addressable memory (TCAM) is a key component in various digital systems due to its fast lookup operation. Symmetric and asymmetric TCAM cells are two widely used cells for implementing a TCAM array. This paper presents several comparison fault models of TCAMs with asymmetric cells based on electrical defects. Some new comparison faults which do not exist in a TCAM with symmetric cells are found. One march-like test algorithm TAC-H is also proposed to cover the defined comparison faults. The TAC-H consists of 8N Write operations and (3N + 2B) Compare operations for an N × B-bit TCAM with Hit output only. We also propose two march-like diagnosis algorithms to identify the defined comparison faults of TCAMs with asymmetric cells. The first diagnosis algorithm DAC-H requires 5N Write operations, 3N Erase operations, and (5N + 2B) Compare operations to distinguish 100 percent comparison faults for a TCAM with Hit output only. The second diagnosis algorithm DAC-P requires 3N Write operations, 1N Erase operations, and (5N + 2B) Compare operations to distinguish 100 percent comparison faults for a TCAM with Hit and priority address encoder outputs.
INDEX TERMS
table lookup, content-addressable storage, fault diagnosis, erase operation, ternary content addressable memory, digital system, lookup operation, asymmetric TCAM cell, TCAM array, fault model, electrical defect, march-like test algorithm, write operation, march-like diagnosis algorithm, Fault detection, Memory management, Content management, ternary CAM, comparison fault, march test, Memory testing, diagnosis, content addressable memory (CAM)
CITATION
Jin-Fu Li, "Testing and Diagnosing Comparison Faults of TCAMs with Asymmetric Cells", IEEE Transactions on Computers, vol. 61, no. , pp. 1576-1587, Nov. 2012, doi:10.1109/TC.2011.196
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