A deterministic approach for hardware fault injection in asynchronous QDI logic

This paper presents a new approach for hardware based fault injection in Quasi Delay Insensitive (QDI) asynchronous circuits. Configurable saboteurs are placed at points of interest in the circuit and allow to inject various types of faults on an arbitrary number of signals. These saboteurs not only redefine the logic value of a faulty signal but also the exact moment of the fault occurrence. In asynchronous logic, signal events rather than time are used to trigger on a circuit´s state. Our concept allows to precisely control the order of concurrent signal events. It can be shown that the fault sensitivity highly depends on that event ordering. Thereby a deterministic and reproducible investigation of QDI circuits in the presence of transient and permanent faults in hardware is obtained. The work is evaluated by fault injection experiments on different circuits.