Aliasing-free error detection (ALFRED)

Aliasing, which is the mapping of a faulty circuit's signature onto the fault-free signature, is a major problem in signature analysis. The authors present a new design technique (ALFRED) for zero aliasing based on the concept of sequence detection. For a test sequence of length n, the length of the signature in ALFRED is Theta (log n). The authors reduce the circuit complexity by adopting a shift-register-like structure that minimizes the logical dependencies of all but one of the flip-flops. They relate the theory of balanced functions to ALFRED, and demonstrate the feasibility of the approach by using it to design a signature analyzer for a carry-lookahead adder.<>