Test Data Compression Using Selective Sparse Storage

For today’s very large scale integrated circuits, test data volume is recognized as a major contributor to the cost of manufacturing testing. Test data compression addresses this problem by reducing the test data volume without affecting the overall system performance. This paper proposes a new test data compression technique using selective sparse storage. Test sets are partitioned into four kinds of blocks of uniform length, all-0 blocks, all-1 blocks, sparse blocks and characterless blocks. Blocks are encoded appropriately based on the occurrence of them. They are encoded into 0, 10, 110 + number of the sparse bits + locations of all the sparse bits, and 111 + the block itself, respectively. Two algorithms are proposed for how to select the sparse blocks from test sets. A theoretical analysis for our selective sparse storage shows the new compression technique outperforms the conventional test data compression approaches. Experimental results illustrate the flexibility and efficiency of the new method, which is consistent with the theoretical analysis.