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.