Minimal C-testable tests for block-CLA adders

This paper examines the testing of Carry Look-Ahead (CLA) adders and block-CLA adders with inter-block carry-ripple. By analysing the testing and fault-effect propagation of each stage of the adder, the paper derives minimal test sets for simple CLAs. The generality of these allows them to be assembled to produce minimal 'C-testable' test sets for block-CLA adders. The special cases of unequal block sizes and of no carry-in are also covered. The paper also examines the differing test requirements of the two different forms of CLA adders, the exclusive-OR form and the inclusive-OR form.