Marcilei A. G. Silveira

Total ionizing dose effects on the digital performance of irradiated OCTO and conventional fully depleted SOI MOSFET

This paper investigates and compares experimentally the total ionizing dose (TID) effects in digital parameters of the fully depleted (FD) OCTO Silicon-On-Insulator (SOI) n-type Metal-Oxide-Semiconductor Field Effect Transistor (MOSFET) (OSM), that presents an octagonal gate geometry, versus its conventional (rectangular gate geometry) counterpart (CSM). The main digital parameters taken into account in this study are the threshold voltage (VTH), subthreshold slope (SS), on-state drain current (ION) characteristics. This work demonstrates that OCTO layout style achieved higher radiation tolerance in terms of VTH and SS relative variation and keeping the higher ION performance, due to the LCE and PAMDLE effects existent in the OCTO layout style. In addition the OSM had a significant improvement in terms of the leakage drain current (ILEAK), whereas the CSM ILEAK performance was degraded.

Analyzing Reliability and Performance Trade-Offs of HLS-Based Designs in SRAM-Based FPGAs Under Soft Errors

The increasing system complexity of FPGA-based hardware designs and shortening of time-to-market have motivated the adoption of new designing methodologies focused on addressing the current need for high-performance circuits. High-Level Synthesis (HLS) tools can generate Register Transfer Level (RTL) designs from high-level software programming languages. These tools have evolved significantly in recent years, providing optimized RTL designs, which can serve the needs of safety-critical applications that require both high performance and high reliability levels. However, a reliability evaluation of HLS-based designs under soft errors has not yet been presented. In this work, the trade-offs of different HLS-based designs in terms of reliability, resource utilization, and performance are investigated by analyzing their behavior under soft errors and comparing them to a standard processor-based implementation in an SRAM-based FPGA. Results obtained from fault injection campaigns and radiation experiments show that it is possible to increase the performance of a processor-based system up to 5,000 times by changing its architecture with a small impact in the cross section (increasing up to 8 times), and still increasing the Mean Workload Between Failures (MWBF) of the system.

Analysis of SRAM-Based FPGA SEU Sensitivity to Combined EMI and TID-Imprinted Effects

This work proposes a novel methodology to evaluate SRAM-based FPGAs susceptibility with respect to Single-Event Upset (SEU) as a function of noise on VDD power pins, TotalIonizing Dose (TID) and TID-imprinted effect on BlockRAM cells. The proposed procedure is demonstrated for SEU measurements on a Xilinx Spartan 3E FPGA operating in an 8 MV Pelletron accelerator for the SEU test with heavy-ions, whereas TID was deposited by means of a Shimadzu XRD-7000 X-ray diffractometer. In order to observe the TID-induced imprint effect inside the BlockRAM cells, a second SEU test with neutrons was performed with Americium/Beryllium (241AmBe). The noise was injected into the power supply bus according to the IEC 61.000-4-29 standard and consisted of voltage dips with 16.67% and 25% of the FPGAs VDD at frequencies of 10 Hz and 5 kHz, respectively. At the end of the experiment, the combined SEU failure rate, given in error/bit.day, is calculated for the FPGAs BlockRAM cells. The combined failure rate is defined as the average SEU failure rate computed before and after exposition of the FPGA to the TID.

Heavy Ions Induced Single Event Upsets Testing of the 28 nm Xilinx Zynq-7000 All Programmable SoC

The recent advance of silicon technology has allowed the integration of complex systems in a single chip. Nowadays, Field Programmable Gate Array (FPGA) devices are composed not only of the programmable fabric but also by hard-core processors, dedicated processing block interfaces to various peripherals, on-chip bus structures and analog blocks. Among the latest released devices of this type, this work focuses in the 28 nm Xilinx Zynq-7000 All Programmable SoC (APSoC). While not immune to the radiation environment in space, the Zynq-7000 seems to be very attractive for the aerospace sector due to its high computational power capability and low-power consumption. In this work, results from heavy ions testing for Zynq-7000 are presented. The experiments were performed in a Brazilian facility located at the University of São Paulo, Brazil.

Reliability on ARM Processors Against Soft Errors Through SIHFT Techniques

ARM processors are leaders in embedded systems, delivering high-performance computing, power efficiency, and reduced cost. For this reason, there is a relevant interest for its use in the aerospace industry. However, the use of sub-micron technologies has increased the sensitivity to radiation-induced transient faults. Thus, the mitigation of soft errors has become a major concern. Software-Implemented Hardware Fault Tolerance (SIHFT) techniques are a low-cost way to protect processors against soft errors. On the other hand, they cause high overheads in the execution time and memory, which consequently increase the energy consumption. In this work, we implement a set of software techniques based on different redundancy and checking rules. Furthermore, a low-overhead technique to protect the program execution flow is included. Tests are performed using the ARM Cortex-A9 processor. Simulated fault injection campaigns and radiation test with heavy ions have been performed. Results evaluate the trade-offs among fault detection, execution time, and memory footprint. They show significant improvements of the overheads when compared to previously reported techniques.

Analysis of SRAM-Based FPGA SEU Sensitivity to Combined Effects of Conducted EMI and TID

This work proposes a novel methodology to evaluate SRAM-Based FPGA SEU susceptibility to noise on VDD power pins and total-ionizing dose (TID). The procedure was demonstrated for SEU measurements on a Xilinx Spartan 3E FPGA operating in an 8MV Pelletron accelerator, whereas TID was deposited by means of a Shimadzu XRD-7000 X-ray diffractometer. The injected noise on power supply bus comprised of voltage dips of 16.67% and 25% of VDD at two different frequencies 10Hz and 5kHz, and was performed according to the IEC 61.000-4-29 international standard.

Dynamic distribution of potassium in sugarcane.

In this work the distribution of potassium in sugarcane has been studied during its growth. The soil was prepared with natural fertilizers prepared with sugarcane bagasse. For the measurement of potassium concentration in each part of the plant, gamma-ray spectrometry was used to measure gamma-rays emitted from the radioisotope (40)K. The concentrations of potassium in roots, stems and leaves were measured every two to three months beginning about five months after planting the sugarcane. The results show a higher concentration of potassium at the beginning of plant development and over time, there is an oscillatory behavior in this concentration in each part of the plant, reaching a lower concentration in the adult plant. To describe the evolution of potassium distribution in sugarcane we proposed a phenomenological model assuming that the potassium incorporation rate is proportional to the difference between the element concentration in the plant and a very long term equilibrium value and it is coupled to a resource-limited growth model. The proposed model succeeded in interpreting the results for the potassium distribution in stems and leaves during the sugarcane growth.

A Commercial off-the-shelf pMOS Transistor as X-ray and Heavy Ion Detector

Recently, p-channel metal-oxide-semiconductor (pMOS) transistors were suggested as fit for the task of detecting and quantifying ionizing radiation dose. Linearity, small detection volume, fast readout, portability, low power consumption and low radiation attenuation are some of the pMOS advantages over PIN diode and thermoluminiscent dosimeters. A hand-held measurement system using a low power commercial off-the-shelf pMOSas the sensor would have a clear advantage due to the lower cost incurred by a standard technological process. In this research work, we tested the commercial device 3N163 regarding its behaviouras an X-ray sensor, as well as its possible application as a heavy-ion detector. To study the radiation effects of X-rays, a XRD-7000 (Shimadzu) X-ray diffraction setup was used to produce 10-keV effective energy photons. Heavy ions tests involved 12C, 16O, 19F, 28Si, 35Cl, 63Cu and 107Ag beams scattered at 15° by a 275 μg/cm2 gold target, which provide LETs (Linear Energy Transfer) from 4 to 40 MeV/mg/cm2. The signal readout was done using a 1 GHz oscilloscope with a 10-Gsamples/s conversion rate, high enough to permit the recording of transient pulses in the drain current. In this case, an ion can cause a current signal proportional to the ion beam used. Through this study it was found that a simple commercial pMOS device can be reliably used as a detector of X-rays as well as heavy ion detector.

First Successful SEE Measurements with Heavy Ions in Brazil

In this work, the first successful SEE measurements with heavy ions in Brazil is reported. The heavy ions were produced at the São Paulo 8 UD Pelletron accelerator. ¹²C, ¹⁶O, ¹⁹F, ²⁸Si, ³⁵Cl, ⁶³Cu and ¹⁰⁷Ag heavy ion beams were used to test a commercial off-the-shelf transistor. During irradiation, the response of a pMOS transistor was continuously monitored to measure the SEE events. In order to achieve a uniform low intensity beam the heavy ions were Rutherford scattered at 15⁰ by a 275 μg/cm² gold foil.

Absorbed Gamma‐Ray Doses due to Natural Radionuclides in Building Materials

This work is devoted to the application of high‐resolution gamma‐ray spectrometry in the study of the effective dose coming from naturally occurring radionuclides, namely 40K, 232Th and 238U, present in building materials such as sand, cement, and granitic gravel. Four models were applied to estimate the effective dose and the hazard indices. The maximum estimated effective dose coming from the three reference rooms considered is 0.90(45) mSv/yr, and maximum internal hazard index is 0.77(24), both for the compact clay brick reference room. The principal gamma radiation sources are cement, sand and bricks.