A don't care identification method for test compaction

In this paper, a don't care (X) identification method for test compaction is proposed to reduce the number of test patterns. An X-identification method identifies many X inputs of test patterns in a given test set. However, conventional X-identification methods may be less effective for application-specific fields such as test compaction since the X-bits concentrate on particular primary inputs. The number of X-bits for each primary input in an initial test set becomes uniform by the proposed method. Thus, the efficiency of test compaction is improved. The experimental results for ITC'99 and ISCAS'89 benchmark circuits show that a given initial test set can be efficiently compacted by the proposed method.