Multiple-fault detection for the balanced and unbalanced conditional-sum adders

In this paper the pair-fault (pf) model (Arjhan and Deshmukh 1998), its concept of multiple fault boundaries (MFBs) and fault-dominance are applied to detect multiple stuck-at faults of the conditional-sum type adders' carry-tree. There are 2n+1 test patterns (n is the operand width) to be applied through the primary inputs of the carry binary-trees. The tree can be balanced or unbalanced. For this purpose, the architecture of the adders is reformulated such that they will correspond to the parallel-prefix lookahead adders and the proof of testability is then followed.