Survey of Test Data Compression Technique Emphasizing Code Based Schemes

As a result of the emergence of new fabrication technologies and design complexities, standard stuck-at scan tests are no longer sufficient. The number of tests and corresponding data volume increase with each new fabrication process technology. The demand goes to well beyond 100X tester cycle reduction considering new fault models. The test data compression has been an emerging need of VLSI field and the hot topic of research for last decade. Still there is a great need and scope for further reduction in test data volume. This reduction must be lossless for input side test data. This paper summarizes the different methods based on coding theory applied for lossless compression of the input side test data. It covers starting with simple code based methods to combine/hybrid methods. The basic goal here is to prepare survey on current methodologies applied for test data compression and prepare a platform for further development in this avenue.