A new placement algorithm for the optimization of fault tolerant circuits on reconfigurable devices

Reconfigurable logic devices such as SRAM-based Field Programmable Gate Arrays (FPGAs) are nowadays increasingly popular thanks to their capability of implementing complex circuits with very short development time and for their high versatility in implementing different kind of applications, ranging from signal processing to the networking. The usage of reconfigurable devices in safety critical fields such as space or avionics require the adoption of specific fault tolerant techniques, like Triple Modular Redundancy (TMR), in order to protect their functionality against radiation effects. While these techniques allow to increase the protection capability against radiation effects, they introduce several penalties to the design particularly in terms of performances. In this paper, we present an innovative placement algorithm able to implement fault tolerant circuits on SRAM-based FPGAs while reducing the performance penalties. This algorithm is based on a model-based topology heuristic that address the arithmetic modules implemented on the FPGA reducing the interconnection delays between their resources. Experimental evaluations performed by means of timing analysis and fault injection on two industrial-like case studies demonstrated that the proposed algorithm is able to improve the running frequency up to the 44% versus standard TMR-based techniques while maintaining complete fault tolerance capabilitie

Analysis of SET propagation in Flash-based FPGAs by means of electrical pulse injection

Advanced digital circuits are increasingly sensitive to single event transients (SETs) phenomena. Technology scaling has resulted in a greater sensitivity to single event effects (SEEs) and more in particular to SET propagation, since transients may be generated and propagated through the circuit logic, leading to behavioral errors of the affected circuit. When circuits are implemented on Flash-based FPGAs, SETs generated in the combinational logic resources are the main source of critical behavior. In this paper, we developed a technique based on electrical pulse injection for the analysis of SETs propagation within logic resources of Flash-based FPGAs. We outline logic schematic that allows the injection of different SET pulses. We performed several experimental analyses. We characterized the basic logic gates used by circuits implemented on Flash-based FPGAs evaluating the effect on logic-chains of real lengths. Additionally, we performed an effective analysis evaluating the SET propagation through microprocessor logic paths. Results demonstrated the possibility of mitigating SET-broadening effects by acting on physical place and route constraint