Test data volume minimization using double hamming distance reordering with mixed RL-Huffman based compression scheme for system-on-chip

One of the major challenges in testing a system-on-chip is dealing with the large volume of test data. To reduce the volume of test data several test data compression techniques have been proposed. This paper mixes two encoding techniques to reduce test data volume. First we present a Multi Code compression (MCC) scheme based on different run-length coding techniques (Golomb, Frequency-Directed Run-length, alternating Run Length, Extended Frequency-Directed run length and IFDR). First, we apply double hamming distance based reordering techniques to the test vectors. Next, we present a new MCC scheme that utilizes all the advantageous properties of all the run-length based compression techniques into one single scheme resulting in higher compression ratio. Finally, we apply Huffman encoding technique to further improve the compression ratio. In addition, we present a generalised decompression architecture for this mixed RL-huffman based compression with a low area overhead. The effectiveness of the proposed scheme has been demonstrated by applying it to the test vectors for ISCAS´89 benchmark circuits generated using Synopsys Tetramax ATPG and MILEF ATPG, also a compression with other run length codes has been made.