基于镜像对称参考切片的多扫描链测试数据压缩方法

为了减少测试数据和测试时间，该文提出一种基于镜像对称参考切片的多扫描链测试数据压缩方法。采用两个相互镜像对称的参考切片与扫描切片做相容性比较，提高了相容概率。若扫描切片与参考切片相容，只需要很少的几位编码就可以表示这个扫描切片，并且可以并行载入多扫描链；若不相容，参考切片被该扫描切片替换。提出一种最长相容策略，用来处理扫描切片与参考切片同时满足多种相容关系时的选取问题。根据Huffman编码原理确定不同相容情况的编码码字，可以进一步提高测试数据的压缩率。实验结果表明所提方法的平均测试数据压缩率达到了69.13%。

Test Data Compression Method for Multiple Scan Chain Based on Mirror-symmetrical Reference Slices

In order to reduce test data and test time, a test data compression method for multiple scan chain which bases on mirror-symmetrical reference slices is proposed. This method uses two mutually mirror-symmetrical reference slices for compatibility comparison with scan slice, that improves the compression ratio. If the scan slice is compatible to one of the reference slices, only a few bits are needed to encode it and can be loaded in parallel. Otherwise, the scan slice will replace one reference slice. A longest compatibility strategy is proposed when the scan slice and reference slice satisfy more compatible relationship. It can further improve the test compression ratio to determine the code word according to the different compatibility frequency statistics situations. The experimental results show that the average compression rate of the proposed scheme reaches 69.13%.