Search Results (79)

The increase in small satellites demands the integration of commercial components to reduce costs and development time. However, the lack of standardized system-level methodologies to mitigate radiation-induced degradation limits their adoption. Although majority-carrier technologies such as MOSFET transistors dominate space power electronics, modern commercial off-the-shelf BJT transistors present a robust and cost-effective alternative. This paper evaluates the viability of the new-generation commercial off-the-shelf BJT transistors in space radiation environments by analyzing their response to total ionizing dose (measured at the circuit level) and single-event effects (inferred from component-level data). A fault-tolerant design methodology is proposed based on the strict definition of the safe operating area: the collector-emitter voltage is limited to safe values to mitigate single-event burnout, and an overdrive margin, specifically a 5× worst-case factor, is applied to compensate for the parametric degradation of the current gain. These strategies are empirically validated through two circuits: a voltage clamp and a proportional base driver operating in the 5 W to 40 W range. Experimental tests on the voltage clamp demonstrate stable operation up to one hundred kilorads, exceeding the 50 krad mission requirement by 100%. This indirectly supports the proportional base driver through shared mitigation principles, which rely on base current over-dimensioning to compensate for TID degradation. In conclusion, by applying appropriate derating rules, commercial off-the-shelf BJT transistors constitute a viable and robust alternative for small satellite power systems, mitigating the need for expensive radiation-hardened components. Full article

Data collected by sensors plays a critical role in system decision-making. Microphone arrays enable distance measurement and fault localization, which is particularly critical in the radiation environments of nuclear facilities. Acoustic localization based on microphone arrays can effectively fulfill this requirement. This study experimentally evaluates the Total Ionizing Dose (TID) effects of ⁶⁰Co γ-ray radiation on commercial MEMS (micro-electro-mechanical systems) silicon microphones. Five identical microphone units were simultaneously irradiated at a dose rate of 0.0342 Gy(Si)/s while continuously monitoring operating current and spectral response. Experimental results show that the commercial MEMS silicon microphones exhibit an average TID failure threshold of 932.6 ± 62.8 Gy(Si), with a 95% confidence interval of [875.5, 989.7] Gy(Si). Three degradation/failure levels are clearly defined: channel degradation, channel failure, and full system failure. Radiation exposure causes a progressive increase in operating current (up to 6.7 times the initial value), severe spectral distortion, and ultimately complete loss of localization function. This indicated that standard commercial MEMS silicon microphones possess a certain degree of tolerance to TID radiation. Subsequently, an annealing test was performed. However, Post-irradiation annealing restored the operating current but not the acoustic performance, indicating irreversible radiation-induced damage. Full article

This paper presents a modular Power Conditioning and Distribution Unit (PCDU) designed for small satellites. The proposed system features a highly adaptable architecture capable of managing a total power throughput of up to 100 W, with specific limits defined by mission-dependent thermal and redundancy configurations. Aligned with the New Space paradigm, the implementation relies on Commercial Off-The-Shelf (COTS) components, a strategy that drastically reduces development and manufacturing costs without compromising reliability. The system has been optimized for operation in harsh environments, including high vacuum, ionizing radiation, and extreme thermal gradients. The design incorporates strict redundancy and fault-tolerance criteria to provide a robust solution for critical subsystems. Comprehensive validation was performed through functional testing, Total Ionizing Dose (TID) radiation campaigns, and Thermal Vacuum (TVAC) cycles. Experimental results demonstrate that the PCDU withstands high-vacuum thermal cycling and cumulative radiation doses exceeding 75 kRad. These findings confirm that the developed unit is a cost-effective, high-reliability solution suitable for both Low Earth Orbit (LEO) and deep-space missions. Full article

This study evaluates the applicability of the Advanced Predictor of Electrical Parameters (APEP) methodology to predict the degradation of key electrical parameters in analog-to-digital converters (ADCs) exposed to ionizing radiation, from measurements performed on the non-radiated device. While the APEP method has previously been validated for discrete analog devices, its extension to complex mixed-signal components has not yet been explored. This work addresses this extension using the PRECEDER database. The APEP methodology, based on machine learning techniques, is enhanced through multivariable analysis tools. This study focuses on the Integral Non-Linearity (INL) parameter of the AD574 converter, widely utilized in the aerospace applications. The results demonstrate that the APEP method can be successfully extended to ADCs, improving prediction performance with the incorporation of multiple electrical parameters which are non-radiated measurements. This new improvement is supported by t-Distributed Stochastic Neighbour Embedding (t-SNE), used as an exploratory analysis to reveal non-linear relationships among parameters that are not evident through univariate analysis. Overall, these findings confirm the potential of the multivariable APEP method to reduce the need for costly and destructive radiation testing, contributing to lower validation costs in space environments. Full article

Bipolar junction transistors (BJTs) are susceptible to total ionizing dose (TID) effects in radiation environments, leading to current gain degradation. Addressing the initial-value sensitivity issue in solving the two-dimensional implicit coupled equations within the BJT transceiver current analytical model based on symmetric double-gate MOSFET surface potential theory, this study proposes a machine learning-based BJT surface potential prediction method. This method integrates a classification model, a sample generation model, and a regression model to achieve accurate prediction of BJT surface potential under TID damage. For the sample generation model, a residual Transformer variational autoencoder is designed to enhance the efficiency of generating effective samples. For the regression model, a dynamic exponential weighted mean squared error function is adopted as the loss function for XGBoost to improve the model’s generalization capability. Simulation results demonstrate that at cumulative total doses of 50 and 100 krad(Si), the average relative error between predicted over-base currents and irradiation test results is as low as 0.1847 and 0.2619, respectively, confirming the accuracy of the proposed prediction method. Full article

This paper investigates the degradation characteristics of a DC/DC converter operating under cold redundancy conditions when subjected to total ionizing dose (TID) effects. An optimized RCC isolated auxiliary power supply circuit was evaluated through ⁶⁰Co γ-ray irradiation up to 100 krad(Si) at dose rates of 3.89, 8.89, and 13.89 rad (Si)/s, with electrical characterizations performed at both the system level and the device level, focusing on the critical VDMOS transistors. The results indicate that the main output voltage and conversion efficiency remain essentially stable after irradiation, whereas the auxiliary supply voltage and efficiency degrade significantly, leading to a pronounced reduction in the controller supply margin. Device-level measurements reveal a negative threshold voltage shift of approximately 0.5–1.0 V with clear dose-rate dependence, while the subthreshold swing shows no obvious variation, suggesting that the degradation is primarily dominated by oxide-trapped charge effects. In addition, a substantial increase in drain current at low gate voltages is observed, which may further exacerbate restart risks under cold redundancy conditions. These findings demonstrate that the auxiliary power supply and startup margin constitute critical vulnerability points of cold-redundant DC/DC converters under TID stress and should therefore be primary targets for radiation-hardened design. Full article

This paper reports the results of a system-level total ionizing dose (TID) effect simulation study on a SMIC 130 nm LEON2 processor. Firstly, the device-level simulations of the 130 nm NMOS transistors are performed using the Sentaurus TCAD software to analyze the effects of a bias condition, channel width, and irradiation dose on a TID-induced leakage current. Based on the TCAD simulation results, a Verilog-A-based compact model is developed for NMOS transistors to describe the TID-induced leakage current, and it is then embedded into target nodes of the SPICE netlist for the LEON2 processor, enabling system-level TID simulations. The simulation results reveal the processor’s failure threshold and corresponding failure mechanism; meanwhile, the increase in the power supply current with the irradiation dose is also observed. The research reported in this paper can provide beneficial guidance for radiation performance evaluation and radiation hardening by design (RHBD) in 130 nm bulk CMOS processors. Full article

Silicon carbide (SiC) power converters are increasingly used in automotive, renewable energy, and industrial applications. While reliability assessments are typically performed at either the device or system level, an integrative approach that simultaneously evaluates both levels remains underexplored. This article presents a novel system-level simulation method with two strategies to evaluate the reliability of power devices and a resonant converter under varying temperatures and total ionizing doses (TIDs). Temperature-sensitive electrical parameters (TSEPs), such as on-state resistance ($R_{\mathrm{ON}}$) and threshold voltage shift ($\Delta V_{\mathrm{TH}}$), are calibrated and analyzed using a B1505A curve tracer. These parameters are incorporated into the system-level simulation of a 300 W resonant converter with a boosting cell. Both Silicon (Si) and SiC-based power resonant converters are assessed for power application in space engineering and harsh environments. Additionally, gate-oxide degradation and $\Delta V_{\mathrm{TH}}$-related issues are discussed based on the simulation results. The thermal-strategy results indicate that SiC MOSFETs maintain a more stable conduction loss at elevated temperatures, exhibiting higher reliability due to their high thermal conductivity. Conversely, increased TIDs result in a negative shift in conduction losses across all SiC devices under the radiation strategy, affecting the long-term reliability of the power converter. Full article

This paper focuses on FinFET transistors. The degradation characteristics of FinFET devices after total ionizing dose (TID) radiation in low-temperature environments were investigated by means of a combination of experiments and TCAD simulations. By analyzing the electronic properties of radiation-induced defects in FinFET transistors under low-temperature conditions, the formation and evolution mechanisms of these defects are studied. A physical model for the low-temperature total dose effects of FinFET transistors is established, providing support for the radiation hardening and space applications of FinFET devices. Full article

It is well known that the space radiation environment, which has contributions from the trapped particles within the Van Allen belts, solar energetic particles (SEPs) and galactic cosmic rays (GCRs), directly influences space systems. These systems rely on complex and fragile electronic devices, whose performance can be degraded because of the action of the radiation and its related phenomena: single-event effects (SEEs), displacement damages (DDs) and total ionizing dose (TID). This could cause failures to arise through various mechanisms, ranging from parametric drift failures, such as leakage current and threshold voltage, among others, to destructive effects, like single-event burnout (SEB) or single-event latch-up (SEL). These failures in electronics affect the system’s reliability and its performance, which could compromise the mission’s success. Considering this, the main objective of the SRPROTEC project is to develop and validate new composite materials with better shielding performance against space radiation to increase the radiation tolerance of microelectronic devices encapsulated with these materials. For this purpose, three composites will be synthesized using a liquid epoxy resin filled with silica as a matrix mixed in different proportions, with a high-Z filler. The presence of low-Z elements from the high hydrogen content in the polymer and the presence of high-Z fillers are expected to produce a material with good radiation shielding properties. The developed materials will be exhaustively characterized, subjecting the three composites and control samples to rheological outgassing; gamma radiation shielding; and thermal, electrical, thermomechanical and moisture absorption, among other tests. Finally, the composite with the best performance will be selected and subjected to degradation tests (thermal cycling in vacuum, thermal cycling, thermal shock and relative humidity tests) to determine its suitability for space packaging applications. Full article

A 10 × 10 µm² radiation-tolerant voltage-domain global shutter pixel with radiation-hardened by design (RHBD) device modification is developed to operate under high ionizing-dose rates and high total ionizing-dose (TID) levels. Therefore, a modified NMOS transistor layout is used in the pixel to achieve radiation hardness. The pixel design is demonstrated to operate up to 1 MGy or 100 Mrad (SiO₂) TID with minimal degradation. The global shutter pixel also includes correlated double sampling (CDS) to reduce noise and the impact of the collected carriers generated by the flux of gamma or X-ray radiation. Combined with an external flash, global shutter operation allows short exposures, which limits the impact of radiation on dark current and dynamic range. The pixel is designed using 180 nm CMOS Image Sensor (CIS) technology. Full article

This paper presents a radiation-hardened 4-bit flash analog-to-digital converter (ADC) implemented in a 22 nm fully depleted silicon-on-insulator (FD-SOI) process for high-reliability applications in radiation environments. To improve single-event upsets (SEU) tolerance, the design introduces a compact fault-tolerant logic scheme based on Dual Modular Redundancy (DMR), offering reliability comparable to Triple Modular Redundancy (TMR) while using two storage nodes instead of three, and a simple XOR-based check in place of a majority voter. A distributed sampling architecture mitigates SEU vulnerabilities in the input path, while thin-oxide devices are used in analog-critical circuits to enhance total ionizing dose (TID) resilience. Post-layout simulations demonstrate SEU detection within 200 ps and correction within ~600 ps. The ADC achieves an active area of 0.089 mm², power consumption below 30 µW, and provides a scalable solution for radiation-tolerant data acquisition in aerospace and other high-reliability systems. Full article

This study aims to evaluate the effects of total ionizing dose (TID) radiation on the performance of n−MOSFET current mirrors. We propose an ovel experimental approach to analyze the interaction between charge trapping in the MOSFET gate oxide and the resulting current mirror degradation by subjecting devices to TID doses from 50 krad(Si) to 300 krad(Si) using a 60Co gamma source Experimental data show that threshold voltage shifts by up to 1.31 V and transconductance increases by 27%. This degradation leads to this a reduction of more than 10% in current mirror output accuracy occurs at the highest dose. These quantitative criteria establish a clear benchmark for assessing the impact of TID on current mirror performance. These effects are attributed to positive charge trapping in the gate oxide and at the Si–SiO₂ interface induced by ionizing radiation. This study focuses exclusively on radiation effects; electrical stress phenomena such as over−voltage or electrostatic discharge (ESD) are not addressed. The results highlight the critical importance of accounting for TID effects when designing high−performance n−MOSFET current mirrors for radiation−hardened applications. Full article

This study systematically investigates the mechanism by which total ionizing dose (TID) affects the lifetime degradation of NMOS devices induced by hot-carrier injection (HCI). Experiments involved Cobalt-60 (Co-60) gamma-ray irradiation to a cumulative dose of 500 krad (Si), followed by 168 h annealing at 100 °C to simulate long-term stability. However, under HCI stress conditions (V_D = 2.7 V, V_G = 1.8 V), irradiated devices show a 6.93% increase in threshold voltage shift (ΔV_th) compared to non-irradiated counterparts. According to the IEC 62416 standard, the lifetime degradation of irradiated devices induced by HCI stress is only 65% of that of non-irradiated devices. Conversely, when the saturation drain current (I_Dsat) degrades by 10%, the lifetime doubles compared to non-irradiated counterparts. Mechanistic analysis demonstrates that partial neutralization of E’ center positive charges at the gate oxide interface by hot electrons weakens the electric field shielding effect, accelerating ΔV_th drift, while interface trap charges contribute minimally to degradation due to annealing-induced self-healing. The saturation drain current shift degradation primarily correlates with electron mobility variations. This work elucidates the multi-physics mechanisms through which TID impacts device reliability and provides critical insights for radiation-hardened design optimization. Full article

The impacts of total ionizing dose (TID) were investigated in 28 nm 3D charge trapping (CT) NAND Flash memories. This study focused on the variations in the raw bit error rate (RBER) of irradiated flash across different operational modes and bias states. It was observed that the data pattern stored in Flash influences the bit error count after irradiation. The experimental findings demonstrated a dose-dependent relationship with standby current, read operation current, and threshold voltage shifts. Additionally, TID was found to affect the time required for erasure and programming operations. These results were then bench-marked against similar NAND Flash devices, revealing superior resistance to TID effects. Full article