Ionizing Radiation Detector for Environmental Awareness in FPGA-Based Flight Computers

Ionizing radiation has a detrimental effect on digital electronics which need to operate in extraterrestrial environments. Modern reconfigurable digital fabrics are enabling new architectures for flight computers, which can exploit environmental awareness to increase their fault tolerance. In this paper, we present the design, modeling, and characterization of a radiation sensor which can be coupled with a reprogrammable hardware fabric to provide spatial information about radiation events that can cause logical faults. The sensor uses a wide area PN junction as its fundamental sensing element. As radiation passes through the sensor, electron hole pairs are created. The internal electric field of the PN junction sweeps the charge carriers in opposite directions which are ultimately sensed by orthogonally placed electrodes on the top and bottom of the sensor. This XY grid provides the spatial location of an ionizing radiation strike, which can be fed to the coupled computer fabric for environmental awareness. A reverse bias voltage is applied to the sensor in order to fully deplete the substrate for maximum charge carrier generation. The sensor is designed to detect the spatial location of radiation strikes of energy levels, which can cause faults in commercial field programmable gate arrays substrates.