Syndrome-testable internally unate combinational networks

A combinational network is syndrome-testable with respect to a particular fault if the faulty network realises a function with a different number of ones from the function realised by the fault-free network. Here we investigate the syndrometestability of single stuck-at faults in internally unate combinational networks. We show how such a network can be made syndrome-testable for single stuck-at faults by the addition of a single control line. In the case of a two-level network, at most one additional first-level gate is added to the network.