Noise Figure Research Articles

Multi‐objective reliability‐based robust design for a rock tunnel support system using Pareto optimality

AbstractIn the context of rock material and modeling uncertainties, the optimization of rock tunnel support systems is often conducted by selecting the most cost‐effective solution among several feasible options that typically rely on the engineer's experience, potentially leading to overlooking the most optimal design. To improve such a limitation, this paper presents a multi‐objective reliability‐based robust design, considering the cost, safety, and design robustness systematically while maintaining the computational efficiency. In this framework, the uncertainty‐based reliability constrains is performed using the first‐order reliability method (FORM) and an improved Hasofer–Lind–Rackwits–Fiessler recursive algorithm (iHLRF‐x). The design robustness, in terms of sensitivity index (SI), is evaluated using the normalized gradient of the system response to the noise factors, which can be efficiently obtained from the output of FORM analysis. Then, the Pareto front revealing the tradeoff between multiple objectives can be directly generated using the proposed optimization framework. To illustrate the effectiveness of this procedure, a set of the optimal design combinations of the shotcrete thickness and installation position for the exampled rock tunnel are obtained, and new perspectives pertaining the success of the reliability‐based robust designs are provided.

Online robust parameter design using sequential support vector regression based Bayesian optimization

Traditional robust parameter design (RPD) is an effective offline quality improvement method, but it cannot update the optimal settings in a timely manner. To resolve the drawback of traditional one-time modeling methods, online RPD comes into being. In online RPD, when the setting for controllable factor is unreasonable, it can be regarded as a new sample to update the optimal setting, which improves the efficiency of constructing response surface. Now, one of the mainstream approaches is to use support vector regression (SVR) as a response surface for online RPD. However, in the process of adding samples and updating the response surface, the parameters of the model are not updated. If the parameters do not change after adding samples, the accuracy of the model may decrease, which is obviously not desirable. To address this problem, this paper proposes Bayesian optimization sequential SVR based on online RPD (BOSSVR-RPD) strategy, which can simultaneously update the parameters and response surface in real time. In the proposed strategy, we can use the optimal setting of previously controllable factors, the currently observed noise factor and the corresponding response as new samples to add to the response surface to improve the accuracy of the response surface, and at the same time use the Bayesian optimization method to optimize the parameters of the model. By repeating this process, we can find the desirable optimal setting for controllable factor. This paper verifies the method through four cases, proving that the proposed BOSSVR-RPD strategy can find the optimal setting for controllable factors. Compared with the existing method without parameter optimization, the model proposed in this paper is more accurate, so the optimal setting for controllable factors can be found faster and the controllable factors obtained are more reliable.

Solid-State NMR 13C sensitivity at high magnetic field

Sensitivity is the foundation of every NMR experiment, and the signal-to-noise ratio (SNR) should increase with static (B0) magnetic field, by a proportionality that primarily depends on the design of the NMR probe and receiver. In the low B0 field limit, where the coil geometry is much smaller than the wavelength of the NMR frequency, SNR can increase in proportion to B0 to the power 7/4. For modern magic-angle spinning (MAS) probes, this approximation holds for rotor sizes up to 3.2 mm at 14.1 Tesla (T), corresponding to 600 MHz 1H and 151 MHz 13C Larmor frequencies. To obtain the anticipated benefit of larger coils and/or higher B0 fields requires a quantitative understanding of the contributions to SNR, utilizing standard samples and protocols that reproduce SNR measurements with high accuracy and precision. Here, we present such a systematic and comprehensive study of 13C SNR under MAS over the range of 14.1 to 21.1 T. We evaluate a range of probe designs utilizing 1.6, 2.5 and 3.2 mm rotors, including 24 different sets of measurements on 17 probe configurations using five spectrometers. We utilize N-acetyl valine as the primary standard and compare and contrast with other commonly used standard samples (adamantane, glycine, hexamethylbenzene, and 3-methylglutaric acid). These robust approaches and standard operating procedures provide an improved understanding of the contributions from probe efficiency, receiver noise figure, and B0 dependence in a range of custom-designed and commercially available probes. We find that the optimal raw SNR is obtained with balanced 3.2 mm design at 17.6 T, that the best mass-limited SNR is achieved with a balanced 1.6 mm design at 21.1 T, and that the raw SNR at 21.1 T reaches diminishing returns with rotors larger than 2.5 mm.

LIASM-NRID: Constructing an atmospheric scattering model for low-light conditions and dehazing nighttime road images

Dehazing of nighttime road images holds significant practical relevance for autonomous driving and intelligent transportation systems operating in nocturnal conditions. To address the limitations of traditional atmospheric scattering models in accurately describing the imaging process in low illumination environments such as nighttime, this study constructs a low illumination environment atmospheric scattering model. Based on this newly constructed model, we propose an algorithm specifically designed for dehazing road images at nighttime. The proposed model incorporates an incident light attenuation factor, an additive noise factor, and a global compensation factor related to the scene's depth. The proposed nighttime road image dehazing algorithm firstly suppresses the interference of additive noise in the original image using wavelet decomposition and soft thresholding operation. Then, a transmittance-solving method containing the primary structural information of the image is designed based on the color attenuation linear model, and the solved transmittance is refined based on the interval gradient image texture structure method. Consequently, the global light map estimation process is formulated as an optimization problem to ensure the accuracy of the atmospheric light value calculation. In the final stages, a novel RGB color equalization method is introduced to address the issue of non-uniform incident light color bias in the dehazed images. Additionally, to eliminate the halo problem in the dehazed images, the adaptive histogram equalization algorithm is modified by incorporating a normalized gamma correction function. The experimental results show that the proposed nighttime road image dehazing algorithm exhibits robust performance and generality across various nighttime scenes. Compared with the representative algorithms for nighttime image dehazing, it can get more excellent dehazing results and has more outstanding performance in all numerical evaluation indexes.

Impact ionization coefficients and excess noise in Al0.55Ga0.45As0.56Sb0.44 lattice matched to InP

The avalanche multiplication and noise characteristics of Al0.55Ga0.45As0.56Sb0.44p–i–n and n–i–p structures grown lattice matched on InP have been investigated. From measurements undertaken using 530 nm illumination on several devices, the electron (α) and hole (β) impact ionization coefficients have been determined. While α only shows a relatively small increase compared to the higher Al composition alloys of AlxGa1−xAsSb, β is found to increase significantly. Although the β/α ratio is increased to ∼0.125–0.2, higher than the ∼0.003–0.02 seen in the higher-Al alloys, a relatively low excess noise factor of 2.2 was measured in the p-i-n with electron-initiated multiplication of 20. This noise performance is significantly lower than that predicted using a local-field model and comparable to some commercial silicon APDs. This avalanching material with a bandgap of ∼1.24 eV will have the advantages of a smaller band discontinuity with the absorber region and should also operate at a lower voltage.

An ultra‐low‐power low‐noise amplifier using a combination of current reuse and self‐forward body bias techniques for biomedical applications

SummaryLow‐power low noise amplifiers (LNAs) are critical block in the radio frequency (RF) front‐end of medical device radiocommunications service (MedRadio) receivers for amplifying weak received signals while introducing minimal noise. Despite the inherently low transconductance of MOS transistors, it is possible to achieve low noise, high gain, and good linearity in low power LNAs. This paper presents a combination of techniques to realize an ultra‐low‐power LNA with a compact size and high performance. The proposed LNA utilizes multiple gm‐boosting and self‐forward body bias techniques, with certain transistors operating in weak inversion. Additionally, the Multi‐Objective Inclined Planes System Optimization algorithm is employed to determine the optimal values of the circuit components, thereby achieving the best compromise among the various performance parameters. The proposed LNA with buffer is designed and simulated using an 180 nm CMOS process over the frequency band of 0.3–1 GHz. Simulated results show that the proposed LNA achieves a gain of 19.6 dB, a noise figure of 5.1 dB, good input matching (S11 < −10 dB), and a third‐order intermodulation intercept point (IIP3) of 3.8 dBm. Additionally, it consumes 320 μW (without buffer) from a 1 V power supply, and the chip area is 235 μm × 372 μm. The simulated results demonstrate that the proposed ultra‐low power LNA is a promising candidate for biomedical applications.

SHAP-PDP hybrid interpretation of decision-making mechanism of machine learning-based landslide susceptibility mapping: A case study at Wushan District, China

For landslide prevention and control, it is essential to establish a landslide susceptibility prediction framework that can explain the model’s decision-making process. Wushan County, Chongqing was selected as the study area, and seventeen landslide conditioning factors were initially chosen for this investigation. GeoDetector was used to remove noise factors and reduce the latitude of the data. The research investigates the use of three machine learning methods for assessing landslide susceptibility: SVM, RF, and XGBoost, and finally explains the decision mechanism of the model by SHAP-PDP. The results indicate that XGBoost has better evaluation results than RF and SVM. And XGBoost uncertainty is lower. The integrated interpretation framework based on SHAP-PDP can evaluate and interpret landslide susceptibility models both globally and locally, which is of great practical significance for the application of machine learning in landslide prediction.

Performance parameters estimation of high speed Silicon/Germanium/InGaAsP avalanche photodiodes wide bandwidth capability in ultra high speed optical communication system

Abstract This paper has clarified the performance parameters estimation of high speed silicon/germanium/InGaAsP avalanche photodiodes wide bandwidth capability in ultrahigh speed optical communication system. The basic structure configuration of avalanche photodiode is clarified. The basic depletion region configuration schematic view is demonstrated. As well as the maximum electric field is indicated for impact ionization through avalanche photodiode in the presence of load. Various avalanche photo-detectors multiplication factor is clarified versus reverse bias voltage at room temperature. Different avalanche photo-detectors dark current is measured against avalanche photo-detectors volume at room temperature. Various avalanche photo-detectors effective doping concentration is demonstrated against ambient temperature variations. Si/Ge/InGaAsP avalanche photo-detectors excess noise factor is demonstrated versus the ionization ratio at room temperature (T = 300 K) and different ambient temperature (T = 350 K and T = 400 K). Various avalanche photo-detectors excess noise factor is measured clearly versus the multiplication factor at room temperature. Si/Ge/InGaAsP avalanche photo-detectors excess noise factor is demonstrated versus reverse bias voltage at room temperature. Si/Ge/InGaAsP avalanche photo-detectors noise equivalent power is clarified versus multiplication factor at room temperature. Various avalanche photo-detectors noise equivalent power is studied versus temperature variations. Si/Ge/InGaAsP avalanche photo-detectors sensitivity is measured in relation to the temperature variations. Different avalanche photo-detectors sensitivity is demonstrated in relation to reverse bias voltage variations at room temperature.

Analysis and design of a 0.9 V 1 GHz-BW 14.6 dBm-OIP3 broadband receiver with current-mode analog baseband in 12 nm FinFET CMOS

This study introduces a wideband LNTA-based receiver employing full current mode (FCM) signal transmission, leveraging a broadband and highly linear current-mode analog baseband (CMAB). The CMAB module comprises a shunt feedback low pass filter and a programmable gain amplifier (PGA) with wide bandwidth, utilizing a regulated CG current mirror design, enriched by gm-boosting methodology and positive feedback capacitance reutilization through an identical boost amplifier. Fabricated in 12 nm FinFET CMOS process, the FCM receiver attains notable characteristics including a baseband bandwidth of 1 GHz, a conversion gain of 30 dB, a noise figure of 5.2 dB, and an OIP3 of 14.6 dBm, while operating with a low supply voltage of merely 0.9 V. Simulation results validate the efficacy of this FCM receiver for wideband communication, effectively addressing the linearity constraints associated with low supply voltages and maximizing the advantages of FinFET technology in current-mode signal transmission. The total layout area is 0.484 mm2.

Analyzing the gain and noise characteristics of the Bi/Er co-doped fiber amplifier

In this paper, we present the energy levels, hopping configurations, and numerical models of the Bi/Er co-doped fiber amplifier. Numerical simulations are utilized to solve the rate and power transfer equations of the model. The gain and noise characteristics of the Bi/Er co-doped fiber amplifier are comprehensively compared and analyzed. The results show that providing lower signal power and sufficiently high pump power is beneficial to improving the gain of the Bi/Er co-doped fiber amplifier, and the gain is independent of the pump direction in this case. The forward pump design has the lowest noise figure, followed by the bidirectional and thebackward. Gain spectra in the range of 1360 nm to 1560 nm are predicted. In addition, we have verified the feasibility of the numerical simulation model by comparing it with the experimental data. This analysis provides specific references and guidance for the design and optimization of the Bi/Er co-doped fiber amplifier.

High-gain ultra-wideband bismuth-doped fiber amplifier operating in the O + E + S band.

We present a double-pass bismuth (Bi)-doped fiber amplifier (BDFA) providing high-gain wideband amplification from 1330 to 1480 nm. A peak gain of 38 dB with 4.7 dB noise figure (NF) was obtained at 1420 nm for a -23 dBm input signal, with >20 dB gain from 1335 to 1475 nm. We achieved 30 and 21.5 dB peak gains with 122 nm (1341-1463 nm) and 140 nm (1333-1473 nm) 6 dB-gain bandwidth for -10 and 0 dBm input signal, respectively. For a 0 dBm signal, the power conversion efficiency (PCE) reached 23.7%, and the in-band optical-signal-to-noise ratio (OSNR) across the wideband BDFA was >44 dB. Also, the absorption and luminescence characteristics have been studied for different Bi-doped phosphosilicate fibers (BPSFs) fabricated in-house.

A 7.2‐mW 0.5–7.5‐GHz ultra‐wideband low‐noise amplifier with 4 dB noise figure and 20 dB gain using 40 nm CMOS technology

AbstractThe technology, design procedure, and measurements of an ultra‐wideband (UWB) push–pull high‐performance complementary metal‐oxide semiconductor (CMOS) low‐noise amplifier (LNA) are presented in this letter. While the push–pull LNA exhibits commendable direct current (DC) power consumption, its operational bandwidth is often limited by the inherent parasitic parameters of the transistors. To exploit the parasitic parameters of the transistors, a multipole‐tuning circuit that utilizes pole‐tuning inductors and parasitic capacitors of the MOS to extend the operational bandwidth is proposed. A UWB LNA is implemented using a commercial 40‐nm CMOS process, and the measurement results demonstrate a peak gain of 20.2 dB, an exceptionally wide bandwidth of 0.5–7.5 GHz, a noise figure of 4 dB, and an output power of 3.5 dBm at OP1 dB with 7.2 mW DC power consumption. The chip area of the LNA is a compact 0.26 mm2. Experimental results closely align with simulations, confirming the validity of the concept and showcasing its competitive performance.

Exposome-Wide Association Study of Body Mass Index Using a Novel Meta-Analytical Approach for Random Forest Models.

Overweight and obesity impose a considerable individual and social burden, and the urban environments might encompass factors that contribute to obesity. Nevertheless, there is a scarcity of research that takes into account the simultaneous interaction of multiple environmental factors. Our objective was to perform an exposome-wide association study of body mass index (BMI) in a multicohort setting of 15 studies. Studies were affiliated with the Dutch Geoscience and Health Cohort Consortium (GECCO), had different population sizes (688-141,825), and covered the entire Netherlands. Ten studies contained general population samples, others focused on specific populations including people with diabetes or impaired hearing. BMI was calculated from self-reported or measured height and weight. Associations with 69 residential neighborhood environmental factors (air pollution, noise, temperature, neighborhood socioeconomic and demographic factors, food environment, drivability, and walkability) were explored. Random forest (RF) regression addressed potential nonlinear and nonadditive associations. In the absence of formal methods for multimodel inference for RF, a rank aggregation-based meta-analytic strategy was used to summarize the results across the studies. Six exposures were associated with BMI: five indicating neighborhood economic or social environments (average home values, percentage of high-income residents, average income, livability score, share of single residents) and one indicating the physical activity environment (walkability in buffer area). Living in high-income neighborhoods and neighborhoods with higher livability scores was associated with lower BMI. Nonlinear associations were observed with neighborhood home values in all studies. Lower neighborhood home values were associated with higher BMI scores but only for values up to . The directions of associations were less consistent for walkability and share of single residents. Rank aggregation made it possible to flexibly combine the results from various studies, although between-study heterogeneity could not be estimated quantitatively based on RF models. Neighborhood social, economic, and physical environments had the strongest associations with BMI. https://doi.org/10.1289/EHP13393.

A mm‐wave LNA employing current re‐use and non‐linearity cancellation in 28 nm CMOS for automotive RADAR and 6G receivers

AbstractThis letter reports an 85 GHz low noise amplifier (LNA) employing derivative superposition based non‐linearity cancellation and a current re‐use topology. The LNA employs a two‐stage stacked architecture, each featuring neutralized differential pairs utilizing the same DC current. In derivative superposition, an auxiliary branch consisting of neutralized differential pairs cells is added in the LNA in parallel to stage 1 to ensure non‐linearity cancellation. Layout‐based capacitive neutralization is implemented to improve GMAX, resulting in simplified routing, reduced parasitics, and a more compact layout. The proposed LNA is fabricated in TSMC 28 nm CMOS process and achieves a peak gain of 8.4 dB at 84.2 GHz with a measured 3 dB bandwidth () from 79.4 to 92 GHz. The minimum measured noise figure is 12.8 dB. The LNA draws 34 mA of DC current from a 1.2 V supply. The highly linear LNA with IIP3 +6.5 dBm is tailored for automotive RADAR and 6G receivers.

Study of Silicon Photomultiplier external cross-talk

ptical cross-talk is a critical characteristic of Silicon Photomultipliers (SiPMs) and represents a significant source of the excess noise factor, exerting a substantial influence on detector performance. During the avalanche process of SiPMs, photons generated can give rise to both internal cross-talk within the same SiPM and external cross-talk when photons escape from one SiPM and trigger avalanches in others. In scenarios where SiPMs are arranged in a compact configuration and positioned facing each other, the external cross-talk could even dominate the cross-talk phenomenon. This paper investigates two distinct methods for measuring external cross-talk: the counting method, which involves operating SiPMs face-to-face and measuring their coincident signals, and the reflection method, which employs a highly reflective film attached to the surface of the SiPMs. External cross-talk measurements have been conducted on several types of SiPMs, including Vacuum Ultra-Violet (VUV) sensitive SiPMs that Fondazione Bruno Kessler (FBK) and Hamamatsu Photonics Inc (HPK) produced for nEXO as well as visible-sensitive SiPMs provided by FBK, HPK and SensL Technologies Ltd (SenSL) for JUNO-TAO. The results reveal a significant presence of external cross-talk in all tested SiPMs, with HPK's SiPMs exhibiting a dominant external cross-talk component due to the implementation of optical trenches that effectively suppress internal cross-talk. Furthermore, we found that the number of fired SPADs resulting from internal cross-talk can be described by combining Geometric and Borel models for all tested SiPMs, while the external cross-talk can be predicted using a pure Borel model. These distinct probability distributions lead to different excess noise factors, thereby impacting the detector performance in varying ways.

A data fusion-based approach for structural damage detection with distributed long-gauge strain measurements

Distributed long gauge strain sensing technology has solved the problem of difficult identification of local damage in traditional ‘point’ monitoring, and has received extensive attention in the field of structural damage identification. Owing to the inevitable presence of measurement noise and environmental factors in the macro strain response measurement, a single damage index has also underlined some drawbacks generally arising when multiple damages occur, or errors affect the identified dynamic properties of the systems. To address these challenges, this paper proposes a data fusion method based on the Dempster–Shafer evidence theory, relying on distributed strain sensing technology. The identification results of the modal macro strain-based index and quasi-static macro strain energy-based damage index are fused to make a comprehensive decision on structural damage location. Damage identification studies are conducted on different types of structures under impact loads and random wind loads to verify the effectiveness and accuracy of the proposed data fusion method in the case of single and multiple damage conditions. The results show that the proposed data fusion method can accurately identify the damage location and effectively reduce misjudgment on undamaged locations; it has potential application value in practical structural health monitoring.

A broadband single-ended active-feedforward -noise-canceling LNA with IP2 enhancement in stacked n/pMOS configurations

In this paper, we present a broadband low-noise amplifier (LNA), using active-feedforward noise-cancellation and complementary n/pMOS configurations. Based on traditional common-gate (CG) and common-source (CS) noise canceling topology, the applied active feedforward stage reduces the CG's dc current and alleviates its resistive load tradeoff between noise and headroom. Meanwhile, the active feedforward stage follows the same noise cancellation (NC) principle as the CG transistors. A low noise figure is thus obtained. In addition, the complementary n/pMOS configuration is used to cancel second-order distortions and double current efficiency. Two π-type matching networks are utilized to broaden the bandwidth of S11 and gain. After applying these techniques, an LNA prototype was designed in standard 65 nm CMOS technology. Simulation results display a gain of 14–17 dB and a noise figure (NF) of 2.45–3.45 dB within a bandwidth of 1–12 GHz. The linearity of IIP3 and IIP2 are −2.4 and 23 dBm at 5 GHz. The presented circuit consumes only 7.8 mW of dc power while occupying an area of 0.21 mm2.

Semiconductor Optical Amplifiers with Wide Gain Bandwidth and Enhanced Polarization Insensitivity Based on Tensile-Strained Quantum Wells.

The paper presents a wide-bandwidth, low-polarization semiconductor optical amplifier (SOA) based on strained quantum wells. By enhancing the material gain of quantum wells for TM modes, we have extended the gain bandwidth of the SOA while reducing its polarization sensitivity. Through a combination of tilted waveguide design and cavity surface optical thin film design, we have effectively reduced the cavity surface reflectance of the SOA, thus decreasing device transmission losses and noise figure. At a wavelength of 1550 nm and a drive current of 1.4 A, the output power can reach 188 mW, with a small signal gain of 36.4 dB and a 3 dB gain bandwidth of 128 nm. The linewidth broadening is only 1.032 times. The polarization-dependent gain of the SOA is below 1.4 dB, and the noise figure is below 5.5 dB. The device employs only I-line lithography technology, offering simple fabrication processes and low costs yet delivering outstanding and stable performance. The designed SOA achieves wide gain bandwidth, high gain, low polarization sensitivity, low linewidth broadening, and low noise, promising significant applications in the wide-bandwidth optical communication field across the S + C + L bands.

Comparison of physical and acceptability tests of extra oral suction in rsgm ugm prof. Soedomo

The spread of COVID-19 through aerosols and droplets occurs during dental treatment. Dentists use high-volume suction (HVS) and saliva ejectors to suction saliva, blood, and water from the oral cavity. Since the pandemic, prototyping, production, and use of extraoral suction (EOS) have increased. EOS comprises HEPA (High-Efficiency Particulate Air), plasma ions, and ultraviolet (UV) filters. This study was used to see the effectiveness of the use of EOS through a comparison of physical and acceptability tests on the use of EOS at UGM Prof. Sodeomo Dental Hospital using three EOS brands, Coxo™, Eighteeth™ Vacstation, and Eostra™. Physical Test is used to assess the ability of a tool when used—Acceptability Test to assess user acceptance of EOS based on usage experience. The study was conducted at the UGM Prof. Soedomo Hospital (Professional Education Clinic, Resident Education Clinic, General Service Unit, and Specialistic Service Unit) in 2021 with 90 respondents who were EOS users. The EOS with the most incredible suction power, noise figure, and electrical power was Eostra™, while based on user experience, the EOS that was more accepted and more comfortable for users to use was Coxo™. EOS reduces aerosol exposure during dental treatment, and based on this study, EOS that had good capacity was not necessarily comfortable to use by users; this was because each brand had advantages and disadvantages, so the selection of EOS was adjusted to the capacity of the operator and the practice site.

Quantifying Impacts of Uncertainties on Certification-Driven Design

Airworthiness certification is challenging for novel aircraft concepts. To avoid the significant cost associated with the redesign for certification compliance, incorporating certification requirements into early aircraft design is desired for unconventional aircraft. However, epistemic uncertainties arising from modeling assumptions, and aleatory uncertainties stemming from uncontrollable noise factors may have impacts on the certification analysis and certification-constrained design process. This paper presents an uncertainty quantification study based on a certification-constrained design and optimization study previously conducted for NASA’s Parallel Electric–Gas Architecture with Synergistic Utilization Scheme (PEGASUS) concept. The epistemic uncertainties are modeled through a set of multiplicative factors applied to intermediate disciplinary variables. The sensitivity analysis between design metrics and multiplicative factors reveals that uncertainties in stability and control derivatives can significantly affect certification constraint predictions, and uncertainties in drag approximations have considerable impacts on the vehicle sizing process. The aleatory uncertainties added to flight dynamics simulations include wind velocities and variations of weight and center of gravity. Four representative design candidates are evaluated for their robustness against aleatory uncertainties based on the Monte Carlo simulation performed on noise factors. The results show that aleatory uncertainties can affect the aircraft dynamic responses in flight test simulations, thus compromising certification compliance.