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The advantages and the tradeoffs associated with the use of inverse-mode (IM) silicon–germanium (SiGe) heterojunction bipolar transistors (HBTs) biasing circuitry in radio-frequency (RF) voltage-controlled oscillators (VCOs) have been investigated and the performance of proposed VCOs (IM VCOs) is compared with VCOs with conventional forward-mode (FM) SiGe-HBTs (FM VCOs). Where the high-frequency performance of IM VCOs is inevitably degraded due to unfavorable device optimization unlike FM VCOs, IM VCOs provide acceptable low-GHz VCO circuit performance. In terms of single-event effects (SEEs), the IM VCOs show reduced transient peaks and duration in comparison with conventional FM VCOs. In addition, the performance of the VCOs is analyzed in terms of transient error vector magnitude (TEVM) in an RF receiver (RX) using quadrature phase-shift keying (QPSK) modulation under a radiation environment. The IM VCOs in the RX circuit show better reliability under SEEs, offering 28.2% lower TEVM at a 64 Mb/s data rate, than that of the RX circuit with conventional FM VCOs. Therefore, the application of IM SiGe-HBT biasing circuits for RF VCOs can be a viable SEE-hardening technique for space-based RF systems. The VCO prototype was fabricated using IHP 130-nm SiGe bipolar complementary metal-oxide-semiconductor (BiCMOS) technology. [ABSTRACT FROM AUTHOR]

The present article applies the $k$ -nearest neighbors ($k$ -NN) machine learning (ML) algorithm to detect and correct single-event upsets (SEUs). In particular, this work focuses on SEUs resulting from single-event transients in RF systems carrying modulated data. Pulsed-laser measurements were performed, and the resulting SEUs were used to train separate $k$ -NN algorithms to detect and correct these upsets. The results show that the algorithm correctly classified data into “upset” and “no upset” 99.2% of the time. In addition, the number of symbol upsets was reduced by 30%. Some of the challenges to implementing and deploying this error correction approach in flight systems are discussed. The results of the present work demonstrate the potential benefits of applying ML techniques to the field of radiation effects. [ABSTRACT FROM AUTHOR]

A method to carry out a priori simulations of pulsed-laser-induced single-event effects experiments is reported. Nonlinear optical simulations are conducted to model the 3-D distributions of charge from a laser pulse. These pulsed-laser-induced charge distributions are then incorporated into a charge transport solver to model the movement of charge as the device returns to a steady state. The output of the simulation infrastructure is a current transient from which collected charge and the temporal characteristics of the transient can be determined. This complete approach to modeling, which includes full device structure information, nonlinear optical energy deposition, and the subsequent movement of optically generated charge in a device and measurement circuit, allows for direct comparison between experimental and simulated current transients. A large-area silicon diode was used as the test vehicle, and good agreement was found between simulations and experiments in both total injected charge as well as temporal characteristics. Importantly, the a priori simulation approach does not require knowledge from prior heavy-ion testing, making it a predictive tool with broad versatility and minimal reliance on approximations. [ABSTRACT FROM AUTHOR]

Heavy-ion, focused X-ray, and pulsed laser single-event transient (SET) experiments are performed on a silicon epitaxial diode. Collected charge, transient rise times, and transient fall times are calculated and compared between different sources. The transient shape characteristics depend on the source (ion, X-ray, or laser), even when similar amounts of charge are generated. The observed differences are examined and explained in terms of basic charge collection mechanisms. [ABSTRACT FROM AUTHOR]

Low-noise amplifiers (LNAs) are necessary components for any communications system. Single-event transients (SETs) induced by energetic particles in space can corrupt the data in an RF receiver. Using p-n-p silicon–germanium (SiGe) heterojunction bipolar transistors (HBTs), instead of their more common n-p-n counterparts, has been shown to be an effective mitigation technique in digital, analog, and RF circuits. Since p-n-p SiGe HBTs tend to have lower performance than n-p-n SiGe HBTs, in this article, the tradeoffs between performance and SET robustness have been evaluated through the use of simulations. Two LNAs were designed using an algorithmic design technique: one using only n-p-n SiGe HBTs, and the other using only p-n-p devices. The n-p-n LNA had higher peak gain and lower noise figure at the center frequency of 5 GHz when compared to the p-n-p LNA, by 3.2 and 0.4 dB, respectively. However, the n-p-n LNA also produced transients with amplitudes larger than the p-n-p LNA across all simulated linear energy transfers. Although the p-n-p LNA has lower overall performance, it is also more robust to SETs. Thus, the choice between using n-p-n and p-n-p SiGe HBTs for an RF design will depend on application requirements. [ABSTRACT FROM AUTHOR]

A comparison of heavy-ion-induced single-event transients (SETs) in silicon–germanium heterojunction bipolar transistors (SiGe HBTs) fabricated on both bulk and silicon-on-insulator (SOI) substrates is presented. Experimental heavy-ion data show a reduction of sensitive volume of ≈ 350 × for the SiGe HBTs fabricated on SOI compared to those on a bulk substrate. Furthermore, the results indicate that the sensitive volume of the SOI SiGe HBTs is confined to the intrinsic device. These results have been confirmed using pulsed laser data and TCAD simulations. Limiting the charge collection depth of SiGe HBTs by fabricating them on SOI facilitates correlation of ion and laser results. The improved ease of correlation is a result of suppressing diffusive charge collection mechanisms that are difficult to replicate with the charge deposition profile generated by two-photon absorption using a tightly focused laser beam. However, a potential issue with pulsed laser testing is determining the loss of the pulse energy through the buried oxide, which requires detailed knowledge of the semiconductor platform. Overall, the reduction of sensitive volume for the SOI SiGe HBTs compared to those on a bulk substrate is a clear advantage from a single-event upset vulnerability perspective. [ABSTRACT FROM AUTHOR]

The propagation of single-event transients from the electrical to the photonic domain in a segmented Mach–Zehnder modulator was investigated using pulsed-laser measurements and lumerical simulations. Although electrical transients can heavily degrade the input data to the modulator, almost all of the degradation can be suppressed once it is converted into the optical domain. The mitigation of transients is primarily accomplished by increasing Vπ of each segment, making electrical transients up to 6 V essentially negligible. A “folding” effect of the optical transient is also explained in relation to Vπ. Two radiation-hardening-by-design (RHBD) approaches are suggested to mitigate transient effects. [ABSTRACT FROM AUTHOR]

The single-event transient response of a high-voltage complementary SiGe-on-silicon-on-insulator technology is investigated along with its temperature dependence using a pulse laser. The p-n-p silicon-germanium heterojunction bipolar transistor (SiGe HBT) shows a larger transient peak amplitude compared to the n-p-n SiGe HBT, which is largely related to the differences in total device volume and peak germanium content between the p-n-p and n-p-n devices. The effects of temperature on the transient response are also investigated using heaters and sensors mounted directly on the device-under-test package. The collector transient peak amplitude shows a negative temperature coefficient for a $V {_{\text {CB}}}$ of 0-V condition, for both the n-p-n and p-n-p devices. However, the temperature dependence of the transient peak amplitude becomes significantly weaker at $V {_{\text {CB}}}>0$ V. Calibrated TCAD simulations were performed to better understand the temperature dependence, and the simulations indicated that the electric field and mobility at higher $V {_{\text {CB}}}$ have a reduced temperature dependence than at a $V {_{\text {CB}}}$ of 0 V. The effects of self-heating are also explored using TCAD simulations and show that even under aggressive self-heating conditions, there is only less than 10% reduction in transient peak amplitude with the self-heating models turned on. The results shown suggest that this particular SiGe technology can be used for environments where highly energetic particles and high temperatures are encountered simultaneously. [ABSTRACT FROM AUTHOR]

An approach for determining the optimal laser parameters (i.e., pulse energy, focused spot size, wavelength, and pulse duration) for correlating single-event transients induced via two-photon absorption (TPA) and heavy ions is presented. The approach focuses on identification and extraction of waveform characteristics, or “features,” and minimizing the error between features produced by TPA and ions. Modifying optical parameters can directly impact the waveform features of the TPA-induced transients. Consequently, optimal laser parameters that minimize the error between features extracted for laser- and ion-induced waveforms can be determined. In this paper, the laser pulse energy and spot size were varied, while maintaining a fixed pulse duration and wavelength, and the resulting transients were compared to ion-induced transients. When the optimized optical parameters are used, excellent agreement was achieved between laser- and ion-induced transient waveforms in a silicon-germanium heterojunction bipolar transistor (SiGe HBT). In addition, a one-to-one correlation between heavy-ion linear energy transfer (LET) and laser pulse energy was obtained for a particular spot size ($\omega _{0} = 1.89\,\,\mu \text{m}$ (HW $1/e^{2}$)). These results show that a correlation between LET and pulse energy is achievable when the remaining optical parameters are selected appropriately. Although the results presented are for SiGe HBTs, the generality of the approach should allow it to be extended to other semiconductor platforms. [ABSTRACT FROM AUTHOR]

This paper demonstrates the use of an RF power detector to sense the occurrence of single-event transients (SETs) in RF circuits and systems. The detector was connected to a low-noise amplifier (LNA), and the relationship between the detector output and the LNA transients was investigated via two-photon absorption, pulsed-laser testing, together with mixed-mode TCAD simulations. The response of the detector shows a strong correlation with the RF power of the generated SET. An analytical expression for the detector output is derived and utilized to fit the data. The effects of parameters affecting circuit performance on the detector response to SETs are explored using calibrated TCAD mixed-mode simulations, and design tradeoffs are presented. Finally, a solution to distinguish between transients generated in the detector from those generated in the circuit being monitored is proposed and verified in simulation. The use of detectors to monitor SETs in RF systems could lead to judicious deployment of detection-driven SET mitigation techniques. [ABSTRACT FROM PUBLISHER]

A focused, pulsed x-ray beam was used to compare SET characteristics in pristine and proton-irradiated Al0.3Ga0.7N/GaN HEMTs. Measured SET amplitudes and trailing-edge decay times were analyzed as was the collected charge, obtained by integrating the SET pulses over time. SETs generated in proton-irradiated HEMTs differed significantly from those in pristine HEMTs with regard to the decay times and collected charge. The decay times have previously been shown to be attributed to charge trapping by defect states that are caused either by imperfect material growth conditions or by proton-induced displacement damage. The longer decay times observed for proton-irradiated HEMTs are attributed to the presence of additional deep traps created when protons lose energy as they collide with the nuclei of constituent atoms. Comparison of electrical parameters measured before and immediately following exposure to the focused x-ray beam showed little change, confirming the absence of significant charge buildup in passivation layers by the x-rays themselves. A major advantage of the pulsed x-ray technique is that the region under the metal gate can be probed for single-event transients from the top side, an approach incompatible with pulsed-laser SEE testing that involves the use of visible light. [ABSTRACT FROM PUBLISHER]

The single-event transient (SET) response of a W-band (75–110 GHz) radar receiver front-end is investigated in this paper. A new technique to facilitate the SET testing of the high frequency transceivers is proposed and demonstrated experimentally. The entire radar receiver front-end, including the high frequency signal sources and modulators, were designed and fully integrated in 90 nm 300 GHz SiGe process technology (Global Foundries SiGe 9HP). Two-photon absorption (TPA) laser pulses were utilized to induce transient currents in different devices in various circuit blocks. The study shows how short transient pulses from the high frequency tuned circuits are propagated throughout the receiver and are broadened while passing through low-pass filters present at supply nodes and the low-pass filter following the down-conversion mixer, thus affecting the digital data at the output of the receiver. The proposed methodology allows the study of the effect of SETs on the recovered digital data at the output of the high frequency receivers, thus allowing bit error rate calculations. Comprehensive device and circuit level simulations were also performed, and a close agreement between the measurement results and simulation data was demonstrated. To the authors’ best knowledge, this is the first study of SET on full receiver at millimeter-wave (mmW) frequencies. [ABSTRACT FROM PUBLISHER]

Silicon-germanium heterojunction bipolar transistor (SiGe HBT) models are used in technology computer aided design (TCAD) to investigate single event transients induced by heavy-ion broadbeam and pulsed-laser two-photon absorption sources. A comparison between transient waveforms is provided, the proper extraction of heavy-ion broadbeam transients is discussed (along with circuit implications), and basic laser strike profiles are implemented in TCAD to provide insight into future design practices for simulation software to be used to describe laser-induced upsets in terms of an effective linear energy transfer (LET). [ABSTRACT FROM PUBLISHER]

The single-event transient (SET) response of two different silicon-germanium (SiGe) X-band (8–12 GHz) low noise amplifier (LNA) topologies is fully investigated in this paper. The two LNAs were designed and implemented in 130nm SiGe HBT BiCMOS process technology. Two-photon absorption (TPA) laser pulses were utilized to induce transients within various devices in these LNAs. Impulse response theory is identified as a useful tool for predicting the settling behavior of the LNAs subjected to heavy ion strikes. Comprehensive device and circuit level modeling and simulations were performed to accurately simulate the behavior of the circuits under ion strikes. The simulations agree well with TPA measurements. The simulation, modeling and analysis presented in this paper can be applied for any other circuit topologies for SET modeling and prediction. [ABSTRACT FROM PUBLISHER]

The impact of semiconductor process scaling on the overall transient response of SiGe BiCMOS platforms is investigated. Pulsed-laser two-photon absorption (TPA) and heavy-ion broad-beam testing of SiGe HBT device and digital test structures across several generations of SiGe technologies are utilized to investigate the potential impacts of semiconductor process scaling (e.g., lateral/vertical scaling, changes in doping, Ge content, etc.) on the overall transient shape, magnitude, and duration. Technology scaling is shown to increase the single-event effect (SEE) sensitivity of SiGe HBTs (i.e., elevated collected charge, where 1st Gen. QC <3 rd Gen. QC <4 th Gen. QC ). Modern third-generation and fourth-generation devices under a forward-active bias (i.e., forward-biased EB junction, reverse-biased CB junction) exhibit a large diffusive transient component between the emitter and collector terminals, driving an elevation in collected charge. 3-D TCAD modeling is utilized to understand the fundamental transient mechanisms and assess the primary scaling factors affecting SEE sensitivity. Ion-strike simulations show that bulk traps can substantially enhance the charge collection mechanisms within these devices. These results suggest that SiGe technology scaling may have a strong impact on the radiation-induced transient response of SiGe HBTs, with future SiGe technology generations potentially exhibiting increased sensitivities to single-event effects. [ABSTRACT FROM PUBLISHER]

The single-event transient (SET) response of the pre-amplification stage of two latched comparators designed using either npn or pnp silicon-germanium heterojunction bipolar transistors (SiGe HBTs) is investigated via two-photon absorption (TPA) carrier injection and mixed-mode TCAD simulations. Experimental data and TCAD simulations showed an improved SET response for the pnp comparator circuit. 2-D raster scans revealed that the devices in the pnp circuit exhibit a reduction in sensitive area of up to 80% compared to their npn counterparts. In addition, by sweeping the input voltage, the sensitive operating region with respect to SETs was determined. By establishing a figure-of-merit, relating the transient peaks and input voltage polarities, the pnp device was determined to have a 21.4% improved response with respect to input voltage. This study has shown that using pnp devices is an effective way to mitigate SETs, and could enable further radiation-hardening-by-design techniques. [ABSTRACT FROM PUBLISHER]

A cascode configuration with inverse-mode (IM) common-emitter silicon-germanium (SiGe) heterojunction bipolar transistors (HBTs) is proposed for the mitigation of single-event transients (SETs) in low-noise amplifiers (LNAs). Conventionally, despite their SET-mitigation capability, IM SiGe HBTs have been considered to be unsuitable for active gain stages due to severe degradation in RF performance. However, with the benefits of aggressive technology scaling, the high frequency performance of IM SiGe HBTs has been significantly improved, thereby enabling them to be utilized in active gain stages with acceptable RF performance. The cascode with IM common-emitter and common-base SiGe HBTs is used for a 2.4 GHz prototype LNA and it achieves adequate RF gain (10 dB) and noise figure (1.9 dB). With regard to SET mitigation, a through-wafer two-photon absorption pulsed-laser experiment is conducted to test the efficacy of this radiation-hardening approach in an advanced 90 nm SiGe BiCMOS platform. The proposed IM-SiGe-HBT-based LNA exhibits 85% reduction in transient peaks compared to the conventional forward-mode cascode LNA. [ABSTRACT FROM PUBLISHER]

The propagation of Analog Single Event Transients (ASETs) to multiple outputs of Bipolar Junction Transistor (BJTs) Integrated Circuits (ICs) is reported for the first time. The results demonstrate that ASETs can appear at several outputs of a BJT amplifier or comparator as a result of a single ion or single laser pulse strike at a single physical location on the chip of a large-scale integrated BJT analog circuit. This is independent of interconnect cross-talk or charge-sharing effects. Laser experiments, together with SPICE simulations and analysis of the ASET’s propagation in the s-domain are used to explain how multiple-output transients (MOTs) are generated and propagate in the device. This study demonstrates that both the charge collection associated with an ASET and the ASET’s shape, commonly used to characterize the propagation of SETs in devices and systems, are unable to explain quantitatively how MOTs propagate through an integrated analog circuit. The analysis methodology adopted here involves combining the Fourier transform of the propagating signal and the current-source transfer function in the s-domain. This approach reveals the mechanisms involved in the transient signal propagation from its point of generation to one or more outputs without the signal following a continuous interconnect path. [ABSTRACT FROM PUBLISHER]

Carrier injection by single-photon absorption using ultraviolet optical pulses is used to investigate single-event transients in pristine and proton-irradiated AlGaN/GaN HEMTs. High-precision spatial mapping of defects and traps in AlGaN/GaN HEMT devices identify regions of enhanced SET signals, or “hot spots” that are ascribed to the presence of lattice defects that modify the electric field in the structure. The resulting transient shape and amplitude depend strongly on the specific location of the injected carriers, and vary with changes in gate and drain bias. Proton irradiation significantly alters transient signal shapes, increases the integrated collected charge, and increases density of defects and traps. [ABSTRACT FROM PUBLISHER]

The capability of inverse-mode (IM) silicon- germanium (SiGe) heterojunction bipolar transistors (HBTs) for the mitigation of single-event transients (SETs) under large-signal operation was investigated in an RF down-conversion single- balanced mixer using a through-wafer, two-photon absorption pulsed-laser beam experiment and TCAD heavy-ion simulations. The IM SiGe HBTs replace conventional forward-mode (FM) SiGe HBTs in the differential pair, which provides full current steering for frequency mixing operation. Under steady-state conditions, the IM SiGe HBT differential pair exhibits smaller transient peaks with shorter durations compared to the FM SiGe HBTs. In addition, under the injection of a local oscillator (LO) signal with large swing, the IM SiGe HBTs show faster recovery (50% reduction in the best case) from the impact of SETs. In the frequency domain, it is observed that IM SiGe HBTs produce less distortion at the output for an intermediate frequency below 1 GHz. Based on the performance comparison between FM and IM SiGe HBT down-conversion mixers, system design guidelines to compensate the noise figure degradation associated with using IM SiGe HBTs are discussed. [ABSTRACT FROM AUTHOR]

The single-event transient (SET) response of a SiGe-based, L-band low-noise amplifier (LNA) is investigated, with a focus on providing recommendations for radiation event simulation techniques. Pulsed-laser, two-photon absorption experiments show that the SET sensitivity of the SiGe LNA is highly dependent on operating conditions and strike location. Time and frequency-domain analyses raise potential concerns for digital data modulated on RF carrier signals. Device and circuit-level ion-strike TCAD simulations are utilized to compare alternative simulation approaches, highlight the importance of parasitics on SET simulation accuracy, and suggest best practices for modeling radiation-induced transients within RF/mm-wave circuits. [ABSTRACT FROM AUTHOR]

Focused, pulsed laser-light is used to investigate single-event latchup in an analog-to-digital converter (AD9240) through the generation of charge collection spectra and their dependence on bias, laser pulse intensity and strike location. Large bipolar single-event transients were identified as precursors to latchup. They occurred at bias voltages just below the latchup holding voltage and in regions that became sensitive to single-event latchup at voltages above the holding voltage. Charge collection spectra obtained from spatial scans involving the pulsed laser had features similar to those obtained from heavy-ion irradiation. Both approaches indicated enhanced charge collection at supply voltages just below the holding voltage. [ABSTRACT FROM PUBLISHER]

The single event effect (SEE) response of devices and differential pairs in a 32-nm SOI CMOS technology is explored using laser-induced carrier injection and TCAD simulations. Both nFETs and pFETs in this technology exhibit similar sensitive area to laser-induced SEE and are strongly dependent on the drain bias condition. TCAD simulations were conducted in order to confirm results and utilize a 3-D mixed-mode simulation approach to more accurately model testing conditions. The differential pair (diff. pair) circuit SEE response extends the discussion to include the use of these devices in a core analog/RF circuit block. The analysis includes the use of floating body (FB) and body-connected (BC) devices. Body-connected FETs tend to exhibit a transient response that is much shorter in duration when compared directly to its floating body counterpart. [ABSTRACT FROM PUBLISHER]

The effects of negative feedback, both external and internal, on single event transients (SETs) in SiGe HBT analog circuits are investigated. In order to examine internal negative feedback effects, basic common-emitter NPN current mirrors, with and without emitter degeneration resistors, are utilized. A Wilson current mirror and a Wilson mirror with its intrinsic external feedback removed are used to study external negative feedback effects under the influence of laser-induced single events. The measurement data clearly show notable improvements in SET response that can be made by employing both internal and external negative feedback. The peak transient in the output current is reduced, and the settling time upon a laser strike is shortened significantly by negative feedback. All four investigated current mirrors were fabricated with IBM 8HP 130 nm SiGe BiCMOS technology. [ABSTRACT FROM PUBLISHER]

The single-event transient (SET) response of a third-generation bulk C-SiGe (\ npn + \ pnp) BiCMOS platform is investigated for the first time. Pulsed-laser, two-photon absorption experiments show that the pnp SiGe heterojunction bipolar transistor (SiGe HBT) exhibits a significant reduction in sensitive area as well as an improved transient response compared with the npn SiGe HBT. Ion-strike simulations on 3-D TCAD, C-SiGe HBT models agree with experimental findings, showing a reduction in overall transient duration and collected charge for the pnp SiGe HBT. These improvements in device-level SETs are attributed to the n-well isolation layer present in the vertical material stack of the pnp HBT. These results suggest that precision analog, RF/mm-wave, and high-speed digital applications utilizing unhardened, high-performance bulk pnp SiGe HBTs should benefit from an inherently improved SEE response. [ABSTRACT FROM PUBLISHER]

A SiGe RF low-noise amplifier (LNA) with built-in tolerance to single-event transients is proposed. The LNA utilizes an inverse-mode SiGe HBT for the common-base transistor in a cascode core. This new cascode configuration exhibits reduced transient peaks and shorter transient durations compared to the conventional cascode one. The improved SET response was verified with through-wafer two-photon absorption pulsed-laser experiments and supported via mixed-mode TCAD simulations. In addition, analysis of the RF performance and the reliability issues associated with the inverse-mode operation further suggests this new cascode structure can be a strong contender for space-based applications. The LNA with the inverse-mode-based cascode core was fabricated in a 130 nm SiGe BiCMOS platform and has similar RF performance to the conventional schematic-based LNA, further validating the proposed approach. [ABSTRACT FROM PUBLISHER]

The single-event effect sensitivity of three different commonly employed current mirror circuits, as well as an unconventional inverse-mode current mirror, all implemented in C-SiGe (NPN + PNP) HBT on SOI technology are investigated. Comparisons of the measured data of the basic NPN and PNP current mirror circuits show higher single-event radiation tolerance of PNP SiGe HBTs compared with NPN SiGe HBTs. The concept of utilizing inverse-mode SiGe HBTs in current mirror circuits is investigated. Measurement results validate the feasibility of employing inverse-mode PNP SiGe HBTs in current mirrors and show an excellent resilience against ion-strikes. Full 3-D NanoTCAD models of the SiGe HBTs are developed and used in mixed-mode TCAD simulations (within Cadence) to validate the measurement results. Finally, based on the measurement data and analysis of the four current mirrors, some practical suggestions and observations are offered for operation of such circuits in extreme environments. [ABSTRACT FROM PUBLISHER]