Reconfigurable FPGA Computing to Mitigate for Total Ionizing Dose Effects

We present a novel design technique for hardening field programmable gate arrays (FPGA) against total ionizing dose (TID). There is increasing use of commercial components in space because of its advanced functionality and it is important to recognize that the space radiation environment poses the risk of permanent malfunction due to radiation. Therefore, the integrated circuits used for spacecraft electronics must be resistant to radiation. The amount of threshold voltage shift in MOS devices caused by ionizing radiation is strongly dependant on the bias voltage applied to the gate terminal during radiation. The threshold voltage shift is much less severe under the influence of ionizing radiation if the gate voltage is 0 V with respect to the device substrate. We have direct control of the bias voltage applied to the gate terminal, and therefore can control the rate of threshold voltage shift in the MOS device. Digital electronic circuits can be hardened against TID effects by selectively applying modular redundancy. By applying double modular redundancy, hence, activating one module while the other is inactivated, allows the inactive modules to anneal during its "off cycle. It is shown by means of experimentation that this new design technique provides greatly improved TID tolerance for field programmable gate arrays by means of reconfigurable computing.