Test Data Compression Using Entry Derivative Mode of Dictionary

To lower cost of testing digital integrated circuits, compressing precomputed test set is an effective resolution way. A dictionary compression scheme using entry derivative and two-level coding is proposed based on digits of index far fewer than that of dictionary entry and enormous dont-care bits in test data. The introduced cyclic shift operation can arbitrarily shift dont-care bits in order without losing them so that derivative performances of entries are expanded and number of non-entry vectors is decreased. In addition, two-level regular coding is adopted to reduce volume of code words and complexity of decompression circuit. The experimental results show that the proposed scheme can farther heighten test data compression ratio and decrease test time.