On Test Data Compression Using Selective Don't-Care Identification

摘要

This paper proposes an effective method for reducing test data volume under multiple scan chain designs. The proposed method is based on reduction of distinct scan vectors using selective don 't-care identification. Selective don 't-care identification is repeatedly performed under conditions that each bit of frequent scan vectors is fixed to binary values (0 or 1). Besides, a code extension technique is adopted for shortening the code length for frequent scan vectors in the manner that the code length for rare scan vectors is designed as double of that for frequent ones. The effectiveness of the proposed method is shown through experiments for ISCAS'89 and ITC'99 benchmark circuits.