On the Susceptibility of SRAM-Based FPGA Routing Network to Delay Changes Induced by Ionizing Radiation

This paper presents the results of investigations on the susceptibility of routing network in SRAM-based field-programmable gate arrays (FPGAs) exposed to ionizing neutron radiation creating single-event upset (SEU). A method to configure test circuits mostly with routing resources and few logic resources is presented. Full control over routing resources enables the use of different interconnection types in order to create routing-based oscillators. A method is proposed to route through the 2-D array of switch matrices inside the interconnection network and to automatically identify the involved programmable interconnection points associated with a node. An experimental setup employed to measure delay changes (DCs) induced by single-event upset to the FPGA routing resources, while it is exposed to ionizing neutron radiation, is described. The proposed setup requires no external equipment instruments for DC measurement. The experimental results show that our setup is able to measure induced DCs as low as 5 ps on higher frequency oscillators. Statistical data such as cross sections and mean time to DC are extracted from the results.