On the adders with minimum tests

This paper considers two types of n-bit adders, ripple carry adders and cascaded carry look-ahead adders, with minimum tests for stuck-at-fault models. In the first part, we present two types of full adders consisting of five gates, and show their minimality. We also prove that one of the full adders can be tested by only three test patterns for single stuck-at-faults. We also present two types of 4-bit carry look-ahead adders and their minimum rests. In the second part, we consider the tests for the cascaded adders, an n-bit ripple carry adder and a 4m-bit cascaded carry look-ahead adders. These tests are considerably smaller than previously published ones.