Analog Performance Research Articles

Prediction of coronary artery bypass graft outcomes using a single surgical note: An artificial intelligence-based prediction model study.

Healthcare providers currently calculate risk of the composite outcome of morbidity or mortality associated with a coronary artery bypass grafting (CABG) surgery through manual input of variables into a logistic regression-based risk calculator. This study indicates that automated artificial intelligence (AI)-based techniques can instead calculate risk. Specifically, we present novel numerical embedding techniques that enable NLP (natural language processing) models to achieve higher performance than the risk calculator using a single preoperative surgical note. The most recent preoperative surgical consult notes of 1,738 patients who received an isolated CABG from July 1, 2014 to November 1, 2022 at a single institution were analyzed. The primary outcome was the Society of Thoracic Surgeons defined composite outcome of morbidity or mortality (MM). We tested three numerical-embedding techniques on the widely used TextCNN classification model: 1a) Basic embedding, treat numbers as word tokens; 1b) Basic embedding with a dataloader that Replaces out-of-context (ROOC) numbers with a tag, where context is defined as within a number of tokens of specified keywords; 2) ScaleNum, an embedding technique that scales in-context numbers via a learned sigmoid-linear-log function; and 3) AttnToNum, a ScaleNum-derivative that updates the ScaleNum embeddings via multi-headed attention applied to local context. Predictive performance was measured via area under the receiver operating characteristic curve (AUC) on holdout sets from 10 random-split experiments. For eXplainable-AI (X-AI), we calculate SHapley Additive exPlanation (SHAP) values at an ngram resolution (SHAP-N). While the analyses focus on TextCNN, we execute an analogous performance pipeline with a long short-term memory (LSTM) model to test if the numerical embedding advantage is robust to model architecture. A total of 567 (32.6%) patients had MM following CABG. The embedding performances are as follows with the TextCNN architecture: 1a) Basic, mean AUC 0.788 [95% CI (confidence interval): 0.768-0.809]; 1b) ROOC, 0.801 [CI: 0.788-0.815]; 2) ScaleNum, 0.808 [CI: 0.785-0.821]; and 3) AttnToNum, 0.821 [CI: 0.806-0.834]. The LSTM architecture produced a similar trend. Permutation tests indicate that AttnToNum outperforms the other embedding techniques, though not statistically significant verse ScaleNum (p-value of .07). SHAP-N analyses indicate that the model learns to associate low blood urine nitrate (BUN) and creatinine values with survival. A correlation analysis of the attention-updated numerical embeddings indicates that AttnToNum learns to incorporate both number magnitude and local context to derive semantic similarities. This research presents both quantitative and clinical novel contributions. Quantitatively, we contribute two new embedding techniques: AttnToNum and ScaleNum. Both can embed strictly positive and bounded numerical values, and both surpass basic embeddings in predictive performance. The results suggest AttnToNum outperforms ScaleNum. With regards to clinical research, we show that AI methods can predict outcomes after CABG using a single preoperative note at a performance that matches or surpasses the current risk calculator. These findings reveal the potential role of NLP in automated registry reporting and quality improvement.

Correction: Improved analog and AC performance for high frequency linearity based applications using gate-stack dual metal (DM) nanowire (NW) FET (4 H-SiC)

Correction: Improved analog and AC performance for high frequency linearity based applications using gate-stack dual metal (DM) nanowire (NW) FET (4 H-SiC)

Design, optimization, and performance analysis of GaP/Si heterojunction Fin-TFET with MoS2 nanoribbon channel

This article presents the design and optimization of GaP/Si heterojunction Fin-TFET with a MoS2 channel. The elevated fin structure, coupled with ultrathin MoS2 layers and the tuneable bandgap properties of MoS2 material, significantly enhances gate control over the channel and improves device performance. Additionally, the GaP/Si heterojunction with a heavily doped n-type source pocket leads to a narrow barrier junction, promoting Band-to-Band Tunneling (BTBT). The optimized Fin-TFET boasts exceptional electrical characteristics: a high ON-current (7.72 × 10−5 A/μm), an ultra-low OFF-current (4.16 × 10−17 A/μm), and leading to an outstanding ION/IOFF ratio (7.23 × 1012). Furthermore, the device demonstrates a steep subthreshold slope (SS) of 6 mV/dec (point) and 16.8 mV/dec (average), alongside impressive analog performance with a transconductance (gm) of 2.75 × 10−4 S, a cut-off frequency (fc) of 1.3 × 1012 THz, and a gain-bandwidth product (GBP) of 0.17 × 1012 THz. The entire analysis was conducted utilizing the Sentaurus TCAD-3D simulation tool.

Reactivating and Preserving Interactive Multimedia Artworks: An Analog Performance from the Seventies

Interactive multimedia art shows a complex nature as it is time- and process-based, interconnected with technology, derived by the participation of several authors (artists, technicians, performers, to name a few) and an audience, and it is strongly tied to the moment and space of the original exhibition. These characteristics make the preservation of these artworks a multifaceted process. Building on the foundations developed since the 2000s by international projects focused on preserving and restoring these new art forms, the paper proposes an original model for achieving dynamic preservation, called “the multilevel preservation model”. Since it is no longer possible to guarantee physical integrity for interactive multimedia artworks, dynamic preservation involves recording all the changes that occur to display the artworks in the future. In other words, it makes it possible to record the dynamic authenticity of artworks. The model proposes two fundamental properties: multiple layering, which allows to handle different levels of information about the artwork; multiple belongingness , which allows to represent the dynamic authenticity of the artwork at the archival level and achieving dynamic preservation. The paper demonstrates the high-level implementation of the model by presenting a case study: the reactivation and preservation of an analog video art performance from the 1970s. This case study proposes an interesting real scenario for testing the model, as the reactivation process involved the migration of the entire analog technological apparatus of the artwork into the digital domain.

Analog performance and linearity analysis of a p-type group IV-IV SiGe TFET

Analog performance and linearity analysis of a p-type group IV-IV SiGe TFET

Substitution of Asp29 with Asn29 in the metallochaperone UreE of Streptococcus thermophilus DSM 20617T increases the urease activity and anticipates urea hydrolysis during milk fermentation

Urease operon is highly conserved within the species Streptococcus thermophilus and urease-negative strains are rare in nature. S. thermophilus MIMO1, isolated from commercial yogurt, was previously characterized as urease-positive Ni-dependent strain. Beside a mutation in ureQ, coding for a nickel ABC transporter permease, the strain MIMO1 showed a mutation in ureE gene which code for a metallochaperone involved in Ni delivery to the urease catalytic site. The single base mutation in ureE determined a substitution of Asp29 with Asn29 in the metallochaperone in a conserved protein region not involved in the catalytic activity. With the aim to investigate the role Asp29vs Asn29 substitution in UreE on the urease activity of S. thermophilus, ureE gene of the reference strain DSM 20617T (ureEDSM20617) was replaced by ureE gene of strain MIMO1 (ureEMIMO1) to obtain the recombinant ES3. In-gel detection of urease activity revealed that the substitution of Asp29 with Asn29 in UreE resulted in a higher stability of the enzyme complexes. Moreover, the recombinant ES3 showed higher level of urease activity compared to the wildtype without any detectable increase in the expression level of ureC gene, thus highlighting the role of UreE not only in Ni assembly but also on the level of urease activity. During the growth in milk, the recombinant ES3 showed an anticipated urease activity compared to the wildtype, and analogous milk fermentation performance. The overall data obtained by comparing urease-positive and urease-negative strains/mutants confirmed that urease activity strongly impacts on the milk fermentation process and specifically on the yield of the homolactic fermentation.

Enhancing Oxygen Evolution Reaction through In Situ Electrochemical Oxidation for the Structural Control of Co-Fe Prussian Blue Analogue

The development of exceptionally efficient catalysts for the oxygen evolution reaction (OER) and gaining a deep understanding of their activity is essential for advancing electrochemical conversion technologies. Prussian blue analogues (PBAs) serve as promising pre-catalysts for the OER. However, PBAs, typically prepared through the conventional co-precipitation method, exhibit a lower active site density and limited electrical transport, making them suitable precursors for the derivation of PBA derivatives. In this research, we identified a significant enhancement in the electrocatalytic performance of Co-Fe Prussian blue analogue (CoFe PBA) through electrochemical oxidation. The cubic CoFe PBA was synthesized by one-step co-precipitation method using adjusting the amount of sodium citrate and potassium ferricyanide. After the electrochemical treatment, CoFe PBA demonstrates remarkable attributes, including a low overpotential of 331mV at a current density of 10mA·cm-2, a small Tafel slope of 50.4mV·dec-1, and excellent long-term stability during electrolysis in a 1M KOH alkaline medium for over 37h. Moreover, the electrochemical oxidation of CoFe PBA was comprehensive, employing techniques such as Transmission electron microscope, Powder X-ray diffraction, and X-ray photoelectron spectroscopy. These analyses confirmed the presence of real active substances, including CoOOH and a part of FeOOH species, further supporting the observed improvements in electrocatalytic activity.

Automated design flow for synthesizable ADPLL: From specification to GDS

We propose an automated design flow for an all-digital phase-locked loop (ADPLL) that selects and implements a PLL layout that satisfies user given input specifications using place-and-route (PnR) tools within 1.2 h. The all-digital architecture enables the use of a theory-based frequency domain model for predicting the output specifications once the oscillator performance is characterized. The cell-based digitally controlled oscillator (DCO) is modeled by extracting the PDK and cell specific constants that characterize the effective current to capacitance ratio from only 3 sets of SPICE simulations. The constants are then used to predict the analog performance with an analytical model, which shows an error rate less than 1.5 % for estimating frequency range and power consumption. The generator guides the user to a feasible set of specifications using the analytical model by providing the achievable range of the failed specification. As design examples, 8 generated PLL designs and their post-parasitic performances are compared to input specifications, including one measurement result from a fabricated chip in 65 nm CMOS process.

Body Biasing Techniques for Dynamic Comparators: A Systematic Survey

Forward body biasing (FBB) has often been exploited in the literature for improving the performance of both analog and digital building blocks. Recent works have explored the application of FBB variants to mixed-signal electronics and in particular to dynamic comparators, where these techniques can help to relax the trade-off between speed and power consumption at medium and low supply voltages. However, the literature lacks a structured analysis of the solutions that have been developed and of the trade-offs that affect them. This work attempts to fill the gap by providing a survey of the application of FBB techniques to dynamic comparators. The analysis focuses on the two most popular dynamic comparator topologies, the Strong Arm latch and Elzakker’s comparator. Several FBB variants are examined from a theoretical point of view. Moreover, the benefits and the limitations of the different approaches are assessed in terms of the main figures of merit through a systematic campaign of simulations in a 55 nm CMOS technology.

Reforming of biomass-derived producer gas using toluene as model tar: Deactivation and regeneration studies in Ni and K-Ni catalysts

Within the syngas production from biomass gasification, tar removal constitutes a chief issue to overcome for advanced catalytic systems. This work investigates the performance of Ni and Ni–K catalysts for reforming of derived-biomass producer gas using toluene as model tar. At 750 °C and 60Lg−1h−1, the stability test (70 h) revealed stable performances (CO2, CH4 and C7H8 conversions of 60, 95 and 100%, correspondingly) uniquely for the Ni–K catalyst. Although the efficient protection towards coking let by K was demonstrated, TPO studies over the post-reacted systems still evidenced the presence of carbon deposits for both samples. Conducting three successive reaction/regeneration cycles with different gasifying agents (air, steam and CO2) at 800 °C for 1h, the capability towards regeneration of both catalytic systems was assessed and the spent catalysts were characterized by XRD, SEM and TEM. While none of the regeneration treatments recovered the performance of the unpromoted catalyst, the Ni–K catalysts demonstrated the capability of being fully regenerated by air and CO2 and exhibited analogous catalytic performances after a series of reaction/regeneration cycles. Hence, it is proved that the addition of K into Ni catalysts not only enhances the resistance against deactivation but enables rather facile regenerative procedures under certain atmospheres (air and CO2).

Influence of the Substrate on the Performance of a Co-Prussian Blue Catalyst towards the Water Oxidation under Mild Conditions

Efforts in developing water oxidation reaction (WOR) catalysts mainly focus on Earth-abundant elements with high stability and efficiency. However, the behavior of these materials may vary depending on the electrochemical substrate with which they interact. Understanding the interaction between the catalyst and the substrate can provide valuable insights to advance the design of highly efficient water-splitting devices. In this context, we investigated the influence of different electrochemical substrates on the performance of cobalt-Prussian blue analog (Co-PBA) in WOR under neutral conditions (pH = 7). The results highlight the role of substrate type, including conductive glass (fluorine-doped tin oxide (FTO)), 3D-printed electrodes (3DPE), and Ni-foam, on the electrocatalytic efficiency of Co-PBA. Two methods of Co-PBA synthesis (electrodeposition and drop casting) were employed to understand their effects on morphology, electrochemical properties, and performance in WOR. The results revealed that the substrate and preparation method of Co-PBA can affect the electrochemical behavior, demonstrating differences in electrocatalytic activity, stability, and charge transfer.

Evaluating the impact of anodic oxidation reactions on water splitting using Prussian blue analog-derived metal-(oxy)hydroxides

Prussian blue analog (PBA)-derived Fe–Co(O)OH showed improved anodic oxidation of a series of organic and inorganic compounds without the interference from the oxygen evolution reaction.

Interfacial engineering of Bi2MoO6-BaTiO3 Type-I heterojunction promotes cocatalyst-free piezocatalytic H2 production

Single component semiconductor materials with piezoelectric response can promote the activation of hydrogen ions (H+) and the generation of hydrogen (H2) under the action of mechanical force, but the high recombination rate of carriers is the major obstacle to strengthen piezocatalytic efficiency. Here, a groundbreaking Bi2MoO6-BaTiO3 (BMO-BTO) Type-I heterojunction piezocatalyst is successfully fabricated through a solvothermal strategy, and applied for cocatalysts-free piezocatalytic H2 production reaction. Under ultrasonic vibration, the H2 production rate of BMO-0.1BTO heterojunction can reach up to nearly 152.57 µmol/g/h, which is approximately 9.33 and 4.47 times with respect to that of pristine BMO (16.36 µmol/g/h) and BTO (34.16 µmol/g/h) alone, respectively. Furthermore, BMO is also combined with other commonly used piezocatalysts to construct heterojunctions, and analogous marvelous piezocatalytic H2 production performance was attained. The enhanced piezocatalytic H2 production performance can be credited to the established built-in electric field (BIEF) in heterojunction extraordinarily suppressed the recombination rates of piezocarriers, rather than an increase in piezoelectricity, which is emphatically verified through a series of physics and chemical characterizations. This study presents an innovative paradigm for fabricating BMO-based heterojunction piezocatalyst to efficiently convert mechanical energy into chemical energy.

Analytical modelling and reliability analysis of charge plasma-assisted Mg2Si/Si heterojunction doping less DGTFET for low-power switching applications

Fabrication of tunnel field effect transistor (TFET) confronts various challenges, one of which is random dopant fluctuation (RDF), which diminishes the benefits associated with low subthreshold swing (SS) and high ION/IOFF ratio. By conducting physics-based 2D analytical modelling, this paper proposes a magnesium silicide/silicon (Mg2Si/Si) heterojunction-based doping less double gate tunnel field effect transistor (HB-DL-DGTFET). This work utilizes the concept of charge plasma to tackle the issues of RDF. The analytical analysis in this study is based upon the determination of the center-channel potential by solving 2D Poisson’s equation, considering appropriate boundary conditions. Here, surface potential, electric field, energy bands, drain current and threshold voltage are extracted mathematically. In addition to the aforementioned parameters, several other analog performance parameters like transconductance, drain conductance, device efficiency, intrinsic gain, output resistance and channel resistance have also been studied in this context. The analytical findings have been duly validated using the ATLAS TCAD device simulator. Furthermore, this work focuses on exploring proposed device reliability through an investigation of, the influence of interface trap charges (ITC), present at the Si/SiO2 interface. The study analyses ITC's impact on analog performance and the obtained results are compared with that of conventional doping less DGTFET (C-DL-DGTFET). The simulation results reveal that HB-DL-DGTFET exhibits greater immunity against ITC. Thus, validating the potential of HB-DL-DGTFET as a superior candidate for low-power switching applications.

Impact of temperature variation on linearity parameters of nanotube surrounding gate (NT‐SG) MOSFETs

AbstractThe work investigates the effect of temperature variation on the linearity performance of Nanotube Junctionless Surrounding Gate (NT‐SG) MOSFET. In this study, the linearity parameters of NT‐SG MOSFET is investigated by changing the temperature range from 300 to 500 K using the Silvaco 3D Simulator. For the specified temperature range, characteristics including high‐order trans‐conductance (gm2 and gm3), IIP3, VIP3, and VIP2 have been assessed. All of these metrics exhibit great linearity and little distortion at the NT‐SG MOSFET's zero crossover point for Vds = 0.01 V. The VIP2 and VIP3 are found to be increased when the temperature range increases from 300 to 500 K and thus the device is found to be more suitable for high‐frequency applications. In addition to this, the NT‐SG MOSFET manifests enhanced analog performance and is also more immune toward SCEs.

Numerical study of T-Gate AlGaN/AlInGaN/GaN MOSHEMT with Single and Double Barrier for THz Frequency Applications

This paper presents a comprehensive investigation into the DC analog and AC microwave performance of a state-of-the-art T-gate double barrier AlGaN/AlInGaN/GaN MOSHEMT (Metal Oxide Semiconductor High Electron Mobility Transistor) implemented on a 4H-SiC substrate. The study involves meticulous numerical simulations and an extensive comparison with a single barrier design, utilizing the TCAD-Silvaco software. The observed disparity in performance can be attributed to the utilization of double barrier technology, which enhances electron confinement and current density by augmenting the polarization-induced charge during high-frequency operations. Remarkably, when compared to the single barrier design, the double barrier MOSHEMT exhibits a notable 15% increase in drain current, a 5% increase in transconductance, and an elevated breakdown voltage (VBR) of 140 V in E-mode operation. Furthermore, the radio frequency analysis of the double barrier device showcases exceptional performance, setting new records with a maximum oscillation frequency (fmax) of 1.148 THz and a gain cutoff frequency (ft) of 891 GHz. These impressive results obtained through deck-simulation affirm the immense potential of the proposed double barrier AlGaN/AlInGaN/GaN MOSHEMT for future applications in high-power and terahertz frequency domains.

Design Considerations into Circuit Applications for Structurally Optimised FinFET

FinFETs have gained a lot of demand in the family of multigate FET devices in the recent years. In this view, this manuscript aims to design different FinFET architectures to observe the analog and circuit performance. A total of five structures namely Conventional FinFET, Lightly doped S/D, Underlap FinFET, Single-k spacer, and Dual-k spacer FinFET has been designed and performance has been analysed. The best performance is obtained for dual-k spacer FinFET. Moreover, the dimensional variations such as gate length (Lg), fin width (Wfin) and fin height (Hfin) for the duak-k spacer FinFET is performed and it is found that lowering the Lg and Wfin, and increasing the Hfin would be a better option in order to enhance the device performance. Furthermore, at the optimized device dimensions the circuit analysis for inverter and single stage common source amplifier is performed. The gain for the designed single stage common stage amplifier is noticed to be 1.8155.

Numerical simulation and characterization of high-power gallium nitride based Junctionless Accumulation Mode Nanowire FET (GaN-JAM-NWFET) for small signal high frequency terahertz applications

This paper presents numerical simulation and characterization of high-power Gallium Nitride Junctionless Accumulation Mode Nanowire FET (GaN-JAM-NWFET) which has improved analog performance and is suitable for high-frequency applications. In GaN-JAM-NWFET, GaN and Aluminium Oxide (Al2O3) replace Silicon (Si) and Silicon Oxide (SiO2), respectively. Because of the larger bandgap and strong breakdown field, GaN based devices can handle higher voltages and powers with good carrier transport qualities, which permit a higher driving current than Si devices. Moreover, GaN-JAM-NWFET has a better performance than GaN based Junctionless (JL) NWFET due to the benefit of JAM structure over JL device, having increased carrier mobility in the lightly doped channel. These cumulative benefits of GaN with JAM manifest improvement in drain current, output conductance, subthreshold swing, transconductance, gate capacitance, cut-off frequency, Frequency Transconductance Product (FTP), Gain Frequency Product (GFP), Gain Transconductance Frequency Product (GTFP), intrinsic gain, Unilateral Power Gain (UPG) and Maximum Transducer Power Gain (MTPG) in proposed GaN-JAM-NWFET among GaN-JL-NWFET, Si based JAM NWFET, and Si-JL NWFET devices. The S-parameters such as transmission coefficients (S12 & S21) and reflection coefficients (S11 & S22) also confirm the proposed GaN-JAM-NWFET has better small signal performance than other devices.

Investigating the effects of doping gradient, trap charges, and temperature on Ge vertical TFET for low power switching and analog applications

Influence of Gaussian doping in transistor regions, doping gradient step size (σ), interface trap charges (ITC), and temperature on DC, Analog, and Linearity performance of Ge-Vertical Tunnel FET (VTFET) is explored using Technology Computer-Aided Design. The DC transfer/output characteristics, ION/IOFF ratio, sub-threshold swing(S); and Analog/RF parasitic capacitances (Cgg, Cgs, and Cgd), transconductance (gm), cut-off frequency (ft), Transit time, efficiency, are examined with Doping Gradient in source & drain, σ variance up to 25 nm, and ITC variation from 1010–1012 cm−2 at Al2O3/Ge interface. Further, linearity parameters, such as gm3, VIP2, VIP3, IMD3, IIP3 &CP1-dB are estimated for optimum Ge-VTFET. For reliability analysis, Ge-VTFET is inspected with temperature deviation from 250 K to 375 K. The proposed Ge-VTFET with the doping gradient in drain and σ of 25 nm revealed excellent performance such as low S ∼ 58 mV/dec, high ION/IOFF ratio ∼ 3 × 105, gm ∼ 6.8 µS, ft ∼ 3.96 GHz, and outstanding reliability even under ITC and temperature deviations, proved Ge-VTFET to be an exceptional contender for low-power switching & analog applications.

Performance Enhancement of Dual Material Gate Junctionless FinFETs using Dielectric Spacer

In this work, a detailed investigation is done on the effectiveness of various spacer materials having different spacer lengths (LSP), in improving the performance of Dual-Material Gate-Junctionless FinFET (DMG-JLFinFET). Various performance metrics, such as Drain Induced Barrier Lowering (DIBL), Sub-threshold Swing (SS), ON current (ION), OFF current (IOFF), ratio of ION to IOFF (ION/IOFF), and tunneling current (Itunn), are closely monitored at gate lengths (Lg) down to 10 nm. DIBL degradation of 3.46 mV/V and SS degradation of 4.97 mV/dec are observed when Lg scales down from 30 nm to 10 nm. Except for the case of Itunn, other performance metrics improve with an increase in dielectric constant and length of spacer materials. The optimum performance of DMG-JLFinFET with a channel length of 10 nm is obtained when LSP is 5 nm. Enhancement in analog performance metrics is observed when high κ materials are used as spacers. Transconductance Generation Factor (TGF) improves from 35.86 V−1 to 47.4 V−1 and intrinsic gain increases from 6.93 dB to 11.98 dB when high κ dielectric materials like TiO2 are incorporated as spacers in a DMG-JLFinFET.