Testing and Diagnosing Comparison Faults of TCAMs with Asymmetric Cells

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 ba...

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Bibliographic Details
Published in:IEEE transactions on computers 2012-11, Vol.61 (11), p.1576-1587
Main Author: Li, Jin-Fu
Format: Article
Language:English
Subjects:
Algorithms
Arrays
Asymmetry
comparison fault
content addressable memory (CAM)
Content management
Diagnosis
Digital systems
Encoders
Fault detection
Faults
march test
Mathematical models
Memory management
Memory testing
Studies
ternary CAM
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Summary: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 T AC-H is also proposed to cover the defined comparison faults. The T AC-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 D AC-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 D AC-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.
ISSN:0018-9340
1557-9956
DOI:10.1109/TC.2011.196