Computing bounds for fault tolerance using formal techniques

Continuously shrinking feature sizes result in an increasing susceptibility of circuits to transient faults, e.g. due to environmental radiation. Approaches to implement fault tolerance are known. But assessing the fault tolerance of a given circuit is a tough problem. Here, we propose the use of formal methods to assess the robustness of a digital circuit with respect to transient faults. Our formal model uses a fixed bound in time to cope with the complexity of the underlying sequential equivalence check. The result is a lower and an upper bound on the robustness. The underlying algorithm and techniques to improve the efficiency are presented. In experiments the method is evaluated on circuits with different fault detection mechanisms.