Path-Delay Fault Testing in Embedded Content Addressable Memories

Delay faults in content addressable memories (CAMs) is a major concern in many applications such as network routers, IP filters, longest prefix matching (LPM) search engines and cache tags where high speed data search is significant. It creates the need for analysis of critical paths and detecting associated faults using a minimum number of test patterns. This paper proposes a test method to detect critical path delay faults in CAM systems using a newly proposed low power TCAM cell structure. The proposed complement bit walk (CBW) algorithms are using low time complexity such as 3m+n and 2m+2n operations. The fault simulation of the given TCAM system provides 100% fault coverage for the write, search and pseudo logic faults.