Error masking method based on the short-duration offline test

The method proposed in this article allows to construct error-masking fail-operational systems by combining time and area redundancy. In such a system, error detection is performed online, while error masking is achieved by a short-duration offline test. The time penalty caused by the offline test applies only when an error is detected. The error-masking ability in such a system is very close to TMR, the area overhead is smaller for a well defined class of circuits, and the delay penalty caused by the offline test remains reasonably small. The short-duration offline test is possible only when extensive design-for-test practices are used. Therefore, a novel gate structure is presented, which allows to construct combinational circuits testable by a short-duration offline test. The proposed test offers complete fault coverage with respect to the stuck-on and stuck-open fault model. The proposed solutions are combined and a comprehensive description of the overall error-masking architecture is provided.