Modeling and Testing Comparison Faults of TCAMs with Asymmetric Cells

Ternary content addressable memory (TCAM) is a key component in various applications for 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. A march-like test algorithm is also proposed to cover the defined comparison faults. The test algorithm consists of 8N Write operations and (3N + 2B) Compare operations for an N×B-bit TCAM with Hit output only.