A fast optimal robust path delay fault testable adder

In this paper we explore the test complexity of the adder function with respect to the robust path delay fault model. A lower bound of /spl omega/(n/sup 2/) for the cardinality of a complete test set for a combinational n-bit adder is proven. This result is valid for any adder design known until now. In addition we present a fast O(/spl radic/n)-time adder that is fully robust path delay fault testable with a test set of size /spl Theta/(n/sup 2/).