It is more difficult to accept the increasing test cost for Ics, and hence a simple and high effective solution scheme is proposed in this paper. Cyclic shift technique is applied to test data compression, which can make use of don't bits in test set more effectively than general shift techniques. Combining with XOR logic, the proposed scheme cumulates don't bits and further increase compatibility and inverse compatibility between test vector and its reference vector. According to the statistics of shift state possible occurring, Huffman tree is built and the most optimal code form is found in coding process, so that the utilization ratios of short code words are increased and the use frequencies of long codes are decreased. The presented analysis and experiment results show that the proposed scheme can increase test data compression ratios and decrease test time with very low additional hardware overhead, and is superior to other existing run-length code schemes and similar blocking code ones.%过高的测试功耗和过长的测试应用时间是基于伪随机内建自测试(BIST)的扫描测试所面临的两大主要问题.提出了一种基于扫描子链轮流扫描捕获的BIST方法.在提出的方法中,每条扫描链被划分成N(N＞1)条子链,使用扫描链阻塞技术,同一时刻每条扫描链中只有一条扫描子链活跃,扫描子链轮流进行扫描和捕获,有效地降低了扫描移位和响应捕获期间扫描单元的翻转频率.同时,为检测抗随机故障提出了一种适用于所提出测试方法的线性反馈移位寄存器( LFSR)种子产生算法.在ISCAS'89基准电路上进行的实验表明,提出的方案不但降低约(N-1)/N的平均功耗和峰值功耗,而且显著地减少随机测试的测试应用时间和LFSR重播种的种子存储量.
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