采用循环移位和优化编码的测试压缩方法

摘要

日益增加的集成电路测试成本变得越来越难以接受,因而提出了一种简单而有效的解决方案.该方案把循环移位技术应用到测试数据压缩中,比起一般的移位技术,该方案更能有效地利用测试集中无关位.结合异或逻辑运算,所提方案累积无关位,进一步提高测试向量与其参考向量的相容性和反向相容性.在编码过程中对各种可能移位状态进行统计,建立Huff man树,找出最优化编码形式,因而可以增加短码字的利用率,减少长码字的使用频次.通过给出的分析和实验,说明了所提方案在附加硬件成本很低的情况下既能够提高测试数据压缩率,又能够减少测试时间,优于已发表的游程编码方案和其他同类型的编码压缩技术.%A circuit-under-test can be regarded as a kind of available resource, not only a tested object, in self-feedback testing. By feedback connecting some of the interior nodes of a circuit-under-test to its input terminals, the circuit can generate and apply a test set serially after an initial vector being applied from the outside of the circuit. In this paper, the old grouping method and the feedback nodes assignments are improved. A depth priority algorithm with information matrixes for a common path in a number of directed graphs is presented. The experimental results on ISCAS85 benchmark circuits and MinTest test sets demonstrate that the proposed algorithm can reduce the extra area and improve the fault efficiency.