中文摘要：

航天等领域对集成电路可靠性要求较高，要求其具有在线测试功能，以便及时发现故障，减少损失．结合现有扫描设计方法，设计了一种改进的扫描单元结构．将该扫描单元应用于时序电路后，能够在电路工作的同时进行测试；通过灵活的时钟选择机制，方便地控制电路进行非并发和并发测试．仿真实验表明，应用本文提出的扫描单元，时序电路能够在增加一定硬件冗余的条件下实现在线测试，时间开销较小，有较高的可靠性和一定的容错能力，实用性强．

英文摘要：

For a high reliability, on-line testing is efficient in detecting faults on the early stage. A novel scan cell is proposed based on the conventional scan cell, which can protect the operational status from being changed during test. The test process and the functional operation of sequential circuit go in parallel. With a flexible clock selection mechanism utilized, both non-concurrent test and concurrent test can be operated. Simulation results show that these circuits can be test on-line with moderate hardware redundan- cy, high stability, and negligible time redundancy.