A novel test-data compression technique using application-aware bitmask and dictionary selection methods

Higher circuit densities in System-on-Chip (SOC) designs have led to enhancement in the test data volume. Larger test data size demands not only greater memory requirements, but also an increase in the testing time. Test data compression addresses this problem by reducing the test data volume without affecting the overall system performance. This paper proposes a novel test data compression technique using bitmasks which provides a significant enhancement in the compression efficiency without introducing any additional decompression penalty. The major contributions of this paper are as follows: i) it develops an efficient bitmask selection technique for test data in order to create maximum matching patterns; ii) it develops an efficient dictionary selection method which takes into account the speculated results of compressed codes and iii) it proposes a suitable code compression technique using dictionary and bitmask based code compression that can reduce the memory and time requirements. We have used our algorithm on various test data sets and compared our results with other existing test compression techniques. Our algorithm outperforms the best known existing compression technique up to 30%, giving a best possible compression of 92.2%.