Measuring SER by Neutron Irradiation Between Volatile SRAM-based and Nonvolatile Flash-based FPGAs

We implemented 50k-bit shift registers on SRAM-based and flash-based FPGAs to investigate their radiation hardness. As a result, soft error rates of flip flops on both FPGAs are around 40 FIT/Mbit. Mean time to failure (MTTF) in the SRAM-based one is
$3.8 \times 10^{7}$
hour/failure, while MTTF in flash-based one is
$5.5 \times 10^{9}$
hour/failure. Those results clearly show that in the SRAM-based FPGA must be rebooted or configuration memory must be refreshed much more frequently than the flash-based one.