Testing Comparison Faults of Ternary Content Addressable Memories with Asymmetric Cells

Ternary content addressable memory (TCAM) is one key component in the dedicated hardware modulars for high-performance networking applications. Symmetric and asymmetric cells are two widely used cell structures in TCAMs. An asymmetric cell consists of a binary content addressable memory (BCAM) bit and a mask bit. This paper proposes two march-like test algorithms, T_{H it} an T_PAE, to cover the comparison faults of the BCAM cell and the comparison logic faults of the masking cell. Tan requires IN Write operations and (3N+2B) Compare operations to cover the comparison faults of an NtimesB-bit TCAM with Hit output only. T_PAE requires 4N Write operations and (3N+2B) Compare operations to cover the comparison faults of an NtimesB-bit TCAM with priority address encoder (PAE) output.