A simple model of the accumulation of trapped ionization charges for RADFET dosimeters / Um modelo simples de acumulação de cargas de ionização retidas para dosímetros RADFET

In this work, the modeling of the response variation to the accumulated radiation dose of a RADFET dosimeter is presented. The developed model is based on the variation of the gate voltage threshold of a PMOS transistor as a function of the charges generated by ionizing radiation that are trapped in charge traps in the body and at the gate oxide interface. The modeling was experimentally verified in the irradiation of the PMOS transistor IRF4905PBF with gamma radiation from a 60Co irradiator up to the accumulated dose of 310 krad(Si)

Experimental method for determining the supply current of a PMOS power transistor for use as a RADFET dosimeter

Radiation Sensitive MOSFETs (RADFETs) have been commonly used as ionizing radiation dosimeters. The threshold voltage variation is the main transistor parameter used for radiation dosimetry, as this voltage variation is directly related to total dose and it can be easily determined by using simple measurement and biasing circuits. In this work it is presented a novel experimental method to determine the optimal drain-source current value to be supplied to a p-type MOSFET used in a traditional RADFET configuration (diode connected transistor) for monitoring of the accumulated X- and gamma-radiation dose. Experimental results from irradiations with 60Co gamma-rays and comparison measurements with semiconductor analyzer indicate that lower supply current values result in more precise dose measurement results

Testing a fault tolerant mixed-signal design under TID and heavy ions

This work presents results of three distinctradiation tests performed upon a fault tolerant data acqui-sition system comprising a design diversity redundancytechnique. The first and second experiments are Total Ion-izing Dose (TID) essays, comprising gamma and X-rayirradiations. The last experiment considers single eventeffects, in which two heavy ion irradiation campaignsare carried out. The case study system comprises threeanalog-to-digital converters and two software-based vot-ers, besides additional software and hardware resourcesused for controlling, monitoring and memory manage-ment. The applied Diversity Triple Modular Redundancy(DTMR) technique, comprises different levels of diversity(temporal and architectural). The circuit was designed ina programmable System-on-Chip (PSoC), fabricated in a130nm CMOS technology process. Results show that thetechnique may increase the lifetime of the system underTID if comparing with a non-redundant implementation.Considering the heavy ions experiments the system wasproved effective to tolerate 100% of the observed errorsoriginated in the converters, while errors in the process-ing unit present a higher criticality. Critical errors occur-ring in one of the voters were also observed. A secondheavy ion campaign was then carried out to investigatethe voters reliability, comparing the the dynamic cross sec-tion of three different software-based voter schemes im-plemented in the considered PSoC

Investigating the reliability impacts of neutron-induced soft errors in aerial image classification CNNs implemented in a softcore SRAM-based FPGA GPU

This work was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES) - Finance Code 001, CNPq, FAPERGS, and FINEP (Citar Project) and it has been partially supported by: MultiRad (PAI project funded by Région Auvergne-Rhône-Alpes) and IRT Nanoelec (ANR-10-AIRT-05 project funded by French PIA).International audienceThis work investigates the impacts of neutron-induced soft errors on the reliability of aerial image classification neural networks running on a softcore GPU implemented in an SRAM-based FPGA. We designed and trained fixed-point and floating-point all-convolutional neural networks to classify four-channel aerial images from the SAT-6 dataset, extracted from the U.S. National Agriculture Imagery Program, and implemented on FGPU, a configurable open-source GPU-like processor with floating-point arithmetic hardware. Results from fast neutron and thermal neutron irradiation experiments coupled with configuration bitstream fault injection campaigns show that the impact of soft errors in the aerial image classification must be taken care of with hardening techniques.</p

Analyzing the effects of TID in an embedded system running in a flash-based FPGA

This work analyzes the behavior of a designed embedded system composed of microprocessor, memories and SpaceWire (SpW) links under Total Ionizing Dose (TID) synthesized into a commercial flash-based FPGA from Actel. Two tests were performed: one the FPGA is configured just once at the beginning of the irradiation and the other the FPGA is reconfigured every 5 krad (Si). Results evaluate power supply current (Icc), temperature, function operation and performance degradation