ABSTRACT

The characterization of faulty functions in combinational circuits under stuck-at faults is a relatively unexplored area of research in testing and diagnosis of digital circuits and systems. Existing results reported in this area are mostly concerned with restricted types of functions and circuits. This paper considers two-level combinational circuits realizing arbitrary functions and present many general results which dictate how a fault-free function can be transformed to a feasible faulty function under the stuck-at fault model. A new concept of fault-mapping graph (FMG) is introduced which captures the transitions from a fault-free to its faulty functions. Important properties of FMG are then explored which shed light on general fault behavior in irredundant combinational networks.