A Fault Tolerant Technique for FPGAs

In this paper we present a fault tolerant (FT) technique for field programmable gate arrays (FPGAs) that is based on incrementally reconfiguring circuits and applications that have been previously placed and routed. Our technique targets both logic faults and interconnect faults, and our algorithms can be applied to either static or run-time reconfigurable FPGAs. The algorithm for reconfiguring designs in the presence of logic faults uses a matching technique. The matching technique requires no preplaced, spare logic resources and is capable of handling groups of faults. Experimental results indicate there is little or no impact on circuit performance for low numbers of reconfigured logic blocks. For interconnect faults, we present a rip-up and reroute strategy. Our strategy is based on reading back the FPGA configuration memory, so no netlist is required for rerouting around faulty resources. Experimental results indicate high incremental routability for low numbers of interconnect faults. We also lay the foundation for applying our approach to yield enhancement.