International Journal of Numerical Modelling-Electronic Networks Devices and Fields最新文献

The uncontrollable angles (UAs) in direct torque control (DTC) algorithm is an important issue through which the effects of voltage vectors (VEs) on the magnetic flux and the torque are accurately determined. In this paper, a unique analysis of UAs is performed at different operating conditions, including parameters variations in two different strategies: Direct torque and stator flux control (DTC_SC) and (DTC_RC). Values of Those angles were accurately determined for wide speed, stator and rotor variations, and load changes. In addition, a detailed numerical comparison was performed in terms of these angles in the two strategies mentioned above for each operating condition. The comprehensive comparison showed the superiority of the DTC_RC strategy over its DTC_SC counterpart, being the maximum values of UAs in DTC_RC were 8°, 33°, and 21° versus 15°, 45°, and 38° in DTC_RC strategy for the following operations: Variable speed with variable stator resistance, variable speed with variable stator and rotor resistances, variable speed with variable load, respectively. MATLAB/Simulink results of the contributed analysis and comparisons were accomplished and validated. In addition, DS1103-based experimental tests supported and verified the theoretical analysis.

Medium-speed wind generators in the MW-range with high-temperature superconducting excitation winding are analyzed by means of non-linear 2D and 3D FEM models. Besides an inverter-based sinusoidal stator current feeding, a grid connection via a diode rectifier is analyzed by using coupled FEM and circuit simulations. The newly proposed modeling techniques are used to determine the excitation requirement for speed-variable, unity power factor operation at constant stator voltage, as required for a diode rectifier feeding of the stator winding. 2D FEM models in the H-A-formulation are developed and used for the calculation of the hysteresis loss in the superconducting field winding at stationary operation as well as for an investigation of field current variations in the HTS field winding. The major modeling challenges consist in very long settling times of voltage-fed models, several strong model non-linearities and high requirements on the spatial discretization. Approaches for overcoming these difficulties with reasonable computational efficiency are proposed.

The compact model plays a pivotal role as a critical link between device fabrication and circuit design. While conventional compact model theories and techniques are generally mature, the intricate physical mechanisms of gallium nitride (GaN) high-electron mobility transistors (HEMTs) pose challenges due to their strong non-linearity in high-power radio frequency (RF) applications. This complexity hinders achieving the required precision for applications using traditional modeling methods. Therefore, the development of physics-based compact modeling techniques becomes crucial for a deeper understanding of the intricate features of GaN HEMTs. This paper explores the advancements and the current state-of-the-art in physics-based compact models. The comprehensive review covers both intrinsic core models and real-device effects models. Core models are presented with a focus on fundamental concepts, development overviews, and applications. Additionally, the real-device effects models are introduced, encompassing advanced characterization techniques and modeling methodologies. Furthermore, the paper outlines future trends in physics-based compact modeling, providing valuable insights for individuals engaged in transistor compact modeling work.

In this article, a field-plated and recessed gate III-Nitride Nano-HEMT developed on β-Ga₂O₃ substrate is proposed and investigated for various performance characteristics over different temperatures. The 2DEG (Two Dimensional Electron Gas) dependence on temperature is critical for commercial utilization of GaN-based HEMTs (high electron mobility transistors). Here, the temperature influence on 2DEG for proposed HEMT over the range of 300–400 K has been investigated. The results demonstrate that the 2DEG density of proposed HEMT reduces as temperature increases. It has been observed that phonon scattering results in a sharp decline in the mobility of 2DEG as temperature increases, which causes the electric field to decrease. It also exhibited that the cut-off frequency decreased over the temperature changes from 300 to 400 K due to diminution in electron mobility. This research aims to contribute an extensive overview of proposed III-Nitride Nano-HEMT designed on a lattice-matched substrate of β-Ga₂O₃ to foster future research on the latest developments in this field.

This paper presents a new circuit approach to realize a capacitance multiplier circuit with positive and negative multiplication factors. Based on this approach, two new implementations of positive and negative grounded capacitance multiplier (GCM) circuits are proposed, which utilize only one current follower differential input transconductance amplifier (CFDITA), in conjunction with only one resistor and one virtually grounded capacitor. The presented GCM circuits can enhance a low capacitance value to a very high value (used in low frequency applications), up to 9202 times its original value. An important aspect of the proposed circuits involves designing a lossy parallel inductor circuit by interchanging the passive elements (RC:CR transformation) with each other. The obtained value of the capacitance and inductance can be controlled independently and electronically through the transconductance of CFDITA. The practical usability of the suggested circuits as first and second order filters is discussed. The functionality of the proposed GCM circuits is validated using CMOS CFDITA implemented with 180 nm TSMC technology parameters. Experimental verification of the proposed circuits and application examples is reinforced through the utilization of CFDITA implemented with readily available ICs AD844 and LM13700. These outcomes emphasize the dependability of the suggested circuits.

The increasing complexity of wireless communication systems coupled with shorter design cycles has increased the need for modeling and design methodologies that are both accurate and fast. It is, however, extremely difficult to meet these contradictory requirements using conventional computer-aided design (CAD). Over the past few decades, artificial intelligence (AI) and machine learning (ML) techniques have gained popularity in the RF and microwave community and are increasingly being used. Particularly in recent years, there has been an increase in the use of AI and ML methods for the modeling and design of wireless devices, circuits, and systems, including active device modeling, power amplifier modeling and digital predistortion, passive circuit design and optimization, active circuit design and optimization, wireless power transfer, wireless systems design and optimization and more.

The special issue contains 25 papers that address a variety of topics including AI and ML based device modeling, circuit design and optimization, circuit modeling and digital predistortion, and so forth. Several outstanding contributions to modeling and characterization of electronic devices based on AI and traditional techniques are given.^1-4 Additionally, RF circuit design can benefit from AI and ML techniques, including active circuit design, such as PAs^5-9 and LNA,^{10, 11} and passive circuit design, such as filters.¹² The use of AI methods has also been extended to the modeling and predistortion of dynamic characteristic of circuits and systems, for example, RF PA modeling,^13-15 digital predistortion of high frequency transmitters,¹⁶ suppressing nonlinearity in circuits,^{17, 18} and analyzing circuit crosstalk and phased array errors.^{19, 20} Furthermore, AI methods can also be used to detect circuit defects and cracks.^{21, 22} Along with the aforementioned topics, AI and machine learning methods are applied to organic transistors, solar cells, and digital circuit design.^23-25

From the device level up to the system level, this special issue explores the different branches of knowledge that relate to AI and ML for the modeling and design of wireless devices, circuits, and systems. It is our intention to provide a comprehensive overview of these topics from the reader's point of view as well as useful hints for overcoming the technological challenges of the future.

As Guest Editors, we would like to express our gratitude to Prof. Giovanni Crupi (Editor-in-Chief of Int J Numer Model) for facilitating this special issue. In addition, we would like to thank all authors for their high-quality contributions, as well as all reviewers who took the time and effort to examine the submissions carefully. Readers of

This article centers its attention on the phenomenon of electrostatics, linearity, analogue, and RF performance of a 0.5 μm × (2 × 100) μm double heterojunction AlGaAs/InGaAs/GaAs pHEMT using on-wafer DC and RF measurements up to 50 GHz. With a high I_ON/I_OFF ratio (1.21 × 10⁷) and low subthreshold slope (72.7 mV/dec), a flat and high transconductance over a wide range of V_gs has been achieved for the tested device. Furthermore, the input intercept and higher-order voltage intercept point both attained large values with low intermodulation and harmonic distortion. Regarding RF parameters, the intrinsic gain has been achieved up to 28 dB. The GBW up to 750 GHz was attained, with the highest f_T and f_max values being 24.5 GHz and 99.3 GHz, respectively. Since the device has very low intrinsic capacitance, parameters like TFP, GFP, and GTFP also showed excellent results. The high intrinsic gain and TGF indicate ample potential of the device for use as an amplifier. Investigating the parameters reveals the device to have very good linearity and amplifying capability.

In this work, the harmonic balance approach is applied to a 2D nonlinear finite-element magnetic model with motion, coupled to a nonlinear circuit. The case study comprises a six-pole three-phase surface-mounted permanent magnet generator connected to a six-pulse full-wave diode bridge rectifier. Simulations are performed at fixed generator speed in two operating cases: with an open-circuit DC bus and supplying a load resistance. Both time stepping and harmonic balance approaches are deeply discussed focusing on the model under study, along with relevant implementation details. Harmonic balance results are compared with benchmark time stepping simulations in terms of voltage and current waveforms, progressively expanding the harmonic spectrum. The computational cost of the two approaches is reported as well. Simulation accuracy is satisfying with regard to time stepping benchmark results: relative errors on total harmonic distortion and global root-mean-square values are lower than 3% and 1%, respectively. However, the time stepping approach outperforms the harmonic balance one, due to the relatively short initial transient of the chosen case study. Further improvements on practical implementation are needed to exploit the potentialities of harmonic balance technique.

This study examines the electrical performance characteristics of a ferroelectric vertical tunnel field-effect transistor (TFET) with and without a source pocket (Si_0.5Ge_0.5). The incorporation of Germanium in the source of the TFET aims to enhance the on-current. The Silvaco TCAD simulation tool is utilized to simulate the proposed structure. To improve device performance, a ferroelectric layer with a vertical length is employed in the gate of the TFET. When the ferroelectric layer partially controls the channel region, device characteristics, such as on-current and subthreshold swing (SS) can be improved (i.e., I_ON = 15.21 × 10⁻⁵ A/μm, I_ON/I_OFF = 5.03 × 10⁹, and a minimum SS of 20.87 mV/decade at 300 K). This article studied a comparison between ferroelectric vertical TFETs and nonferroelectric vertical TFETs, as well as ferroelectric vertical TFETs with and without source pockets. The comparison is done on the basis of DC and RF parameters. Analysis of this comparison represents that ferroelectric vertical TFET with source pocket has improved characteristics.

Recently, antiferroelectric and antiferroelectric-like materials have regained interest in electronic devices, such as field-effect transistors, memory, and transducers. Particularly in micro/nano-electromechanical coupling systems such as actuators, these innovative materials, with their peculiar phase transition between antiferroelectric and ferroelectric phases, show promise in offering large electro-strain, fast response, and low power consumption devices. However, compared to numerous computational models of ferroelectric actuators, numerical modeling of antiferroelectric and antiferroelectric-like actuators remains relatively unexplored. In this paper, we propose a phenomenological model of uniaxial antiferroelectric and antiferroelectric-like actuators based on their switching polarization behavior. Specifically, both the double hysteresis loop of antiferroelectric materials and the pinched hysteresis loop of antiferroelectric-like materials can be captured by two hyperbolic tangent functions. This allows us to cast a polarization-dependent strain and piezoelectric tensor into the constitutive laws. The proposed model is then implemented into a finite element framework, in which the voltage-induced deformation can be solved using the Newton–Raphson procedure. Numerical examples of both antiferroelectric and antiferroelectric-like actuators are illustrated and compared with experimental data, showing our proposed model can serve as a useful tool for the design and development of antiferroelectric and antiferroelectric-like actuators.