Applying built-in self-test to majority voting fault tolerant circuits

Testing requirements for the application of built-in self-test to fault tolerant circuits include: (1) detection of all single and multiple faults and (2) verification of correct circuit operation in the presence of faults. Modifications to built-in logic block observer (BILBO) and circular BIST are proposed which make these techniques satisfy both testing requirements. Evaluation of the two modified BIST approaches via single and multiple stuck-at fault simulation in conjunction with a random fault injection procedure indicate that the modified BILBO approach provides better testing results.