Fault emulation: a new approach to fault grading

In this paper, we propose a method of using an FPGA-based emulation system for fault grading. The real-time simulation capability of a hardware emulator could significantly improve the run-time of fault grading, which is one of the most resource-intensive tasks in the design process. A serial fault emulation algorithm is employed and enhanced by two speed-up techniques. First, a set of independent faults can be emulated in parallel. Second, simultaneous injection of multiple dependent faults is also possible by adding extra supporting circuitry. Because the reconfiguration time spent on mapping the numerous faulty circuits into the FPGA boards could be the bottleneck of the whole process, using extra logic for injecting a large number of faults per configuration can reduce the number of reconfigurations, and thus, significantly improve the efficiency. Some modeling issues that are unique in the fault emulation environment are also addressed. The performance estimation indicates that this approach could be several orders of magnitude faster than the existing software approaches for large designs.