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"Switching circuits"
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Simulation-Based DC and RF Performance Analysis of an Enhancement-Mode T-Gate Al0.15Ga0.85N/GaN/Al0.07Ga0.93N/GaN/Al0.05Ga0.95N MIS-HEMT Device on a GaN Substrate
This paper presents a metal–insulator–semiconductor high-electron-mobility transistor (MIS-HEMT) device, operating in enhancement mode, with a double-channel triple-barrier (DCTB) Al0.15Ga0.85N/GaN/Al0.07Ga0.93N/GaN/Al0.05Ga0.95N device structure. Initially, we simulate the Al0.15Ga0.85N/GaN single-channel single-barrier (SCSB) MIS-HEMT, featuring a T-gate design that offers a significant gap between the gate and a drain electrode, resulting in a high breakdown voltage (VBD) and low parasitic capacitance, enhancing cut-off frequency (ft) and a maximum frequency of oscillation (fmax). In the current era, high breakdown voltage, high current drive, and high-frequency enhancement-mode-operated devices are needed for power switching circuits and high-frequency power amplifier applications. To meet these requirements, we propose a DCTB MIS-HEMT device structure that adds additional back-barrier layers and channel layers to form a double-hump characteristic due to the interaction between two-dimensional electron gas (2DEG) accumulation layers and the electric field across the device. We optimize the devices with an optimistic doping profile in channel and buffer layers, a field plate, recessed gate structure, and control the barrier layers thickness, ensuring enhancement-mode operation. Numerical simulations of the DCTB device provide high drain current (Ids) of 1.5 A/mm, transconductance (gm) of 0.232 S/mm, threshold voltage (Vt) of 2.8 V, VBD of 633.1 V, ON resistance (RON) of 6.074 Ω mm, ft of 49.8 GHz, and fmax of 107.8 GHz. Due to improvements in these parameters, the DCTB MIS-HEMT outperforms the SCSB MIS-HEMT, making it suitable for high-current drive, high-frequency, and high-speed switching applications. In this work, we also examine the merits of utilizing DCTB MIS-HEMT as the switching element in an ultra-low-loss boost converter circuit.
Journal Article
Combinational Regularity Analysis (CORA) — a new method for uncovering complex causation in medical and health research
Background
Modern configurational comparative methods (CCMs) of causal inference, such as Qualitative Comparative Analysis (QCA) and Coincidence Analysis (CNA), have started to make inroads into medical and health research over the last decade. At the same time, these methods remain unable to process data on multi-morbidity, a situation in which at least two chronic conditions are simultaneously present. Such data require the capability to analyze complex effects. Against a background of fast-growing numbers of patients with multi-morbid diagnoses, we present a new member of the family of CCMs with which multiple conditions and their complex conjunctions can be analyzed: Combinational Regularity Analysis (CORA).
Methods
The technical heart of CORA consists of algorithms that have originally been developed in electrical engineering for the analysis of multi-output switching circuits. We have adapted these algorithms for purposes of configurational data analysis. To demonstrate CORA, we provide several example applications, both with simulated and empirical data, by means of the eponymous software package
CORA
. Also included in
CORA
is the possibility to mine configurational data and to visualize results via logic diagrams.
Results
For simple single-condition analyses, CORA’s solution is identical with that of QCA or CNA. However, analyses of multiple conditions with CORA differ in important respects from analyses with QCA or CNA. Most importantly, CORA is presently the only configurational method able to simultaneously explain individual conditions as well as complex conjunctions of conditions.
Conclusions
Through CORA, problems of multi-morbidity in particular, and configurational analyses of complex effects in general, come into the analytical reach of CCMs. Future research aims to further broaden and enhance CORA’s capabilities for refining such analyses.
Journal Article
Chaotic ant colony algorithm-based frequency-optimized random switching frequency SVPWM control strategy
To solve the problem where the space vector pulse width modulation (SVPWM) of a three-phase inverter produces large harmonic components near the switching frequency (
f
s
) and its doubling frequency, a frequency-optimized random switching frequency SVPWM (FORSF-SVPWM) control strategy is proposed in this paper. In this strategy, the basic principle of the chaotic ant colony algorithm in path optimization is used to determine the optimized scheme of the switching frequency distribution in the FORSF-SVPWM. Research shows that the frequency sample formed by the sigmoid function curve in the switching frequency range can cause the energy that was originally concentrated on the switching frequency and its doubling frequency to be more evenly distributed in the whole frequency range. Moreover, the amplitude of each harmonic wave is shown to be suppressed. The proposed strategy reduces the high-frequency noise and conducted electromagnetic interference (EMI) existing in power switching circuits. Thus, this strategy is obviously better than the traditional random switching frequency SVPWM (RSF-SVPWM) algorithm with its approximately uniform frequency distribution. Simulation and experimental results show that this strategy can work well in the hardware platform of a three-phase inverter without changing the topology of the main circuit of the system. In addition, this strategy is easy to implement.
Journal Article
Performance evaluation of PI and FLC controller for shunt active power filters
Shunt active power filters (SAPF) play a vital role in power systems. Integration of renewable energy sources and electrical vehicle (EV) charging stations proliferate in the modern power system. In such scenario, SAPF is an efficient method for improving power quality. The article suggests a SAPF with multilevel cascaded H-bridge inverter using the instantaneous real and reactive power (P–Q) theory based control technique to derive reference currents for the compensation unit from active and reactive power to suppress harmonics present in the power system. The conventional-proportional integral (PI) and intelligent-fuzzy logic controller (FLC) were used as voltage controllers for maintaining the DC link voltage. The article proposed an aggregated PWM signal-switching circuit for balancing the individual capacitor voltage. The proposed system harmonic results are compared with conventional triangular PWM and aggregated PWM. The proposed switching circuit balanced the individual capacitor voltage and minimized the total harmonic distortion (THD) in the sinusoidal source voltages and currents. Simulation and prototype results reveals that proposed aggregated PWM system with FLC dominates the conventional PI controller.
Journal Article
A Novel Design of Optical Switch Based on Guided Mode Resonances in Dielectric Photonic Crystal Structures
In this work, a novel idea of optical switch design based on guided mode resonance in the photonic crystal structure is numerically investigated. The designed switching device work on the principle of optical amplification and wavelength shift of data signal with the help of a control signal. The data signal can be coupled into the waveguide using guided-mode resonance, whereas, a control signal is index-coupled into the waveguide to influence the data signal. The optical switching action is optimized by introducing a photonic crystal cavity and varying the number of photonic crystal elements, where the resonant wavelength, reflection peaks, linewidth, and quality factor of the data signal can be adjusted. The device is based on low refractive index contrast dielectric materials compatible with fiber optic communication and can operate in a near-infrared range of around 1.55 μm. The numerical simulations are carried out in an open source finite-difference time-domain-based software. An optical switching action is achieved with 7% amplification in the data signal at a central wavelength of 1.55 µm with a maximum shift of the wavelength of 0.001 µm. The proposed device can be easily implemented in cascade designs of programmable photonic and optical switching circuits.
Journal Article
Energy Management Switch for a Self-Powered Wireless Sensor in Monitoring Power Systems
An efficient switching scheme for magnetically self-powered wireless sensor is proposed. Under a stochastic nature of currents in the power lines, the proposed switch can store excessive harvested energy into a supercapacitor and supply energy for sensing operation when a conductor current becomes extremely low. The smart switching was realized by integrating autonomous switching circuits with digital logic circuits. The self-powered wireless sensors enabled real-time monitoring of power lines for an extended range of the conductor current and sustained sensing operation even during power outages. Moreover, to investigate feasibility of the self-powered sensor running on a commercial LoRa network, harvested power requirement for the network was assessed.
Journal Article
Performance Enhancement of an Electric–Wind–Vehicle with Smart Switching Circuit and Modified Sliding Mode Control
This paper presents a new strategy for wind energy harvesting to enhance the performance of the electric-wind vehicle (EWV). A wind turbine is mounted on the front of an electric-wind vehicle model to capture wind that blows in the opposite direction of the moving vehicle. When the primary battery runs low, the generator switches on, converting wind energy into electricity and storing it in a backup battery. The switching circuit is developed to alternate between the main battery and the backup battery based on the battery capacity level. During the movement of the EWV, the backup battery charges using the wind turbine while the main battery discharges. A modified sliding mode control is used to track the reference speed of the EWV and to regulate the speed by switching between the two batteries. Several scenarios are applied to investigate the proposed strategy. The results show that the proposed strategy can save power by 30% compared to the conventional strategy. Moreover, the modified sliding mode control enhances the EWV’s dynamic performance in contrast to PID control, which shows poor performance (low rise time and low overshoot).
Journal Article
Next-Generation Hybrid RF Front-End with MoS2-FET Supply Management Circuit, CNT-FET Amplifiers, and Graphene Thin-Film Antennas
One-dimensional (1D) and two-dimensional (2D) materials represent the emerging technologies for transistor electronics in view of their attractive electrical (high power gain, high cut-off frequency, low power dissipation) and mechanical properties. This work investigates the integration of carbon-nanotube-based field-effect transistors (CNT-FETs) and molybdenum disulphide (MoS2)-based FETs with standard CMOS technology for designing a simple analog system integrating a power switching circuit for the supply management of a 10 GHz transmitting/receiving (T/R) module that embeds a low-noise amplifier (LNA) and a high-power amplifier (HPA), both of which loaded by nanocrystalline graphene (NCG)-based patch antennas. Verilog-A models, tuned to the technology that will be used to manufacture the FETs, were implemented to perform electrical simulations of the MoS2 and CNT devices using a commercial integrated circuit software simulator. The obtained simulation results prove the potential of hybrid CNT-MoS2-FET circuits as building blocks for next-generation integrated circuits for radio frequency (RF) applications, such as radars or IoT systems.
Journal Article
Exploring chaos and ergodic behavior of an inductorless circuit driven by stochastic parameters
There exist extensive studies on periodic and random perturbations of various smooth maps investigating their dynamics. Unlike smooth maps, non-smooth maps are yet to be studied extensively under a stochastic regime. This paper presents a stochastic piecewise-smooth map derived from a simple inductorless switching circuit. The stochasticity is introduced in parameter values. The distribution of the parameter values is bounded and randomly selected from uniform and triangular distributions and ranges between high and low bifurcation parameter values of the deterministic map. Due to this inherent stochasticity in parameter values, the time evolution of the state variable cannot be predicted at a specific time instant. We observe that the state variable exhibits completely ergodic behavior when the minimum value of the parameter is the same as the minimum bifurcation parameter of the deterministic system. However, the ensemble average of the state variable converges to a fixed value. The system demonstrates nonchaotic behavior for a particular range of parameter values but the deterministic map in that bifurcation range shows interplay between chaos and periodic orbits. The values of Lyapunov exponents decrease monotonically with increased asymmetry of the distribution from which the bifurcation parameter values are chosen. We determine the probability density function of the stochastic map and verify its invariance under initial conditions. The most noteworthy result is the disappearance of chaotic behavior when the lower range of the distribution is varied while maintaining a fixed upper threshold for a particular distribution, even though the deterministic map exhibits an array of periodic and chaotic behaviors within the range. As the period-incrementing cascade with chaotic inclusion only occurs in nonsmooth maps, this paper numerically shows the stochasticity of a piecewise-smooth map obtained from a practical system for the first time where randomness is introduced in the parameter space.
Journal Article