On the Design of Logic Networks with Redundancy and Testability Considerations

Abstract

The presence of redundancy in combinational networks increases the cardinality of the test set to detect all stuck-at-faults. A solution to this problem is to identify and remove all redundancies in the networks before deriving test sets. It is shown in this paper that the identification of redundancy in arbitrary combinational networks is an extremely tedious problem. A class of networks called prime trees is studied for which it is simpler to identify redundancy. Algorithms to design prime trees and also several results on testing the prime trees for fault detection are given. It is established that the fault-detecting test sets for multilevel prime trees are contained in the test sets for “equivalent two-level networks.” Finally, it is observed that the generation of test sets to detect multiple stuck-at-faults is also easily accomplished. Copyright © 1974 by The Institute of Electrical and Electronics Engineers, Inc.