Multicycle tests are useful for test compaction even when full scan allows single- or two-cycle tests to be used. To avoid sequential test generation, multicycle tests can use the test data (scan-in states and primary input vectors) from a single- or two-cycle test set, possibly modified to make it more suitable for multicycle tests. However, the modification process requires repeated fault simulation to prevent a loss of fault coverage. This brief observes that the need to modify test data results from the fact that tests are only extended forward to increase their numbers of clock cycles starting from their (modified) scan-in states. The brief observes further that extending tests backward is a more computationally efficient way of obtaining multicycle tests with modified test data. The brief defines a new type of multicycle test to increase the effectiveness of backward extension and describes a test compaction procedure based on backward and forward extension. It presents experimental results for gate-exhaustive faults, requiring large numbers of tests, in benchmark circuits.

中文翻译：

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通过向后和向前扩展多周期测试来压缩测试

即使完整扫描允许使用单周期或两周期测试，多周期测试对于压缩测试也很有用。为避免生成顺序测试，多周期测试可以使用来自单周期或两个周期测试集的测试数据（扫描状态和主要输入向量），可以对其进行修改以使其更适合于多周期测试。但是，修改过程需要重复进行故障模拟，以防止故障覆盖率降低。该摘要指出，修改测试数据的需要是由于这样的事实，即测试仅从（已修改的）扫描进入状态开始向前扩展以增加其时钟周期数。该简报进一步观察到，向后扩展测试是获得具有修改后的测试数据的多周期测试的更有效的计算方法。该摘要定义了一种新型的多周期测试，以提高后向扩展的有效性，并介绍了基于后向和前向扩展的测试压缩过程。它提供了基准电路中门耗竭故障的实验结果，需要进行大量测试。