Abstract: Data compression is a very effective method to reduce the test cost. An adjacent bit XOR operation based test data compression method was proposed based on bitwise XOR operation between itself and its previous bit, which turned continuous series, such as a series of all 0s and all 1s into series of all 0s, and reversal series, such as a series of 01 and 10 into series of all 1s by bitwise XOR operation between adjacent bits. On one hand, the two kinds of series, continuous series and reversal series, were both taken into account, which decreased the number of division. On the other hand, it increases the minimum encoding run length, so the minimum encoding run length increases from a conventional 0 to 2. The compression ratio is further improved without additional hardware decoding circuitry overhead. The experimental results illustrate the method has a high data compression ratio.

Key words: test data compression, XOR operation, run length, FDR(Frequency Directed Run-Length), EFDR(Extended Frequency Directed Run-Length)