Methodologies for testing embedded content addressable memories

A design strategy is presented for efficient and comprehensive testing when the address, data, and bit lines are not externally controllable or observable. Three algorithms are developed for testing common functional faults in content-addressable memories. One provides a novel method for detecting pattern-sensitive faults over a neighborhood size of nine and thereby tests a w-word content addressable memory in 33w+2b+64 operations, where b is the number of bits in a word. The algorithm is significantly more efficient than other embedded procedures for testing pattern-sensitive faults. Two additional simple algorithms are given for testing embedded content-addressable memories for stuck-at and adjacent-cell coupling faults