A Novel Approach to Drastic Test Data Compression for Multiple Scan Designs

This paper presents a comprehensive test data compression scheme based on adjustable width decompression and X-compact techniques for multiple scan designs. Adjustable width scan chain is employed for test stimuli decompression, and test response takes the advantages of X-compact. A response shaper further minimizes the probability of fault masking. The enhanced broadcast-scan based mode for CUT is able to deal with FFs (flip-fops) with the identical values as well as the opposing values. Two modes can handle the rest compact FF values after filling the unknown values. The merits of proposed approach are as follows. Test storage requirement is reduced significantly, and test input/output pins, test channels coupled with test application time decrease, thus improving test compression ratio completely. The experimental results on benchmark circuits ISCAS´89 demonstrate the improvement upon the previous proposed algorithms.