Switching Transistors Research Articles

Research of Gate-All-Around Field-Effect Transistors

This report provides an overview of GAA FETs also known as Gate-All-Around FETs, focusing on their introduction and limitations, based on a comprehensive review of current literature and online resources. GAA FETs represent an evolution of FinFET technology, which itself was developed from traditional MOSFET designs. Each iteration has aimed to improve performance and overcome limitations of its predecessor. The GAA architecture offers superior electrostatic control, resulting in higher drive currents, reduced leakage, and improved subthreshold swing, making it ideal for high-performance, low-power applications. Despite these advantages, GAA FETs still face challenges with short-channel effects (SCEs) as device dimensions shrink. Gate-All-Around (GAA) is a transistor architecture designed to address the limitations of the FinFET design. Unlike FinFET, where the channel is surrounded on three sides by the gate, GAA surrounds the channel on all four sides by turning the FinFET structure sideways, making the channels horizontal. This design provides enhanced control over the transistor switch. The fabrication of GAA transistors involves a series of highly precise processes, which enable improved transistor scaling with reduced variability, resulting in increased performance and lower power consumption.

Low-energy and tunable LIF neuron using SiGe bandgap-engineered resistive switching transistor

We have proposed leaky integrate-and-fire (LIF) neuron having low-energy consumption and tunable functionality without external circuit components. Our LIF neuron has a simple configuration consisting of only three components: one bandgap-engineered resistive switching transistor (BE-RST), one capacitor, and one resistor. Here, the crucial point is that BE-RST with a silicon–germanium heterojunction possesses an amplified hysteric current switching with a low latch-up voltage due to improved hole storage capability and impact ionization coefficient. Therefore, the proposed neuron utilizing BE-RST requires an energy consumption of 0.36 pJ/spike, which is approximately six times lower than 2.08 pJ/spike of pure silicon-RST based neuron. In addition, the spiking properties can be tuned by modulating the leakage rate and threshold through gate bias, which contributes to energy-efficient sparse-activity and high learning accuracy. As a result, our proposed neuron can be a promising candidate for executing various spiking neural network applications.

Inverter optimization of soft-switching DC-DC converter*

The paper describes the influence of the magnetizing inductance of the transformer on zero-voltage switching of the primary transistors in a soft-switching full-bridge dc-dc converter with a controlled rectifier and turn-off snubber. The optimized version of the transformer allows for achieving a full zero-voltage and zero-current turn-on of the primary transistors in a full-bridge soft-switching DC-DC converter. The analysis is verified by measurements on a laboratory model of the converter. The influence of undischarged output capacitances on the efficiency is measured as well. Also, the impact of the GaN transistors on the zero-voltage switching is discussed.

IP2 optimization in frequency mixers using ferroelectric field-effect transistors

Ferroelectric devices have traditionally been utilized in memory circuits due to their ability to retain a polarization charge and potentially act as a nonvolatile storage device. Their usage in applications unrelated to memory has also previously expanded into other digital and analog circuits, and now, it is being investigated in radio frequency circuits. This work explores the implementation of a frequency mixer using ferroelectric field-effect transistors in order to demonstrate stability against voltage offsets in a single-balanced mixer, making use of the polarization in the switching transistors to improve the performance of the second-order intermodulation product.

Fully Printed Negative-Capacitance Field-Effect Transistors with Ultralow Subthreshold Swing and High Inverter Signal Gain.

The switching of conventional field-effect transistors (FETs) is limited by the Boltzmann barrier of thermionic emission, which prevents the realization of low-power electronics. In order to overcome this limitation, among others, unconventional device geometry with a ferroelectric/dielectric insulator stack has been proposed to demonstrate stable negative-capacitance behavior. Here, the switching of the ferroelectric layer behaves like a step-up amplifier and results in a body factor less than 1. This implies a larger change in the semiconductor surface potential compared to the applied gate voltage variation. The transistors with such ferroelectric/dielectric stack are known as negative-capacitance field-effect transistors (nc-FETs), and can demonstrate a subthreshold slope lower than the Boltzmann's limit (60 mV/decade). While nc-FETs have typically been realized with high-vacuum-deposition processes, here we show fully printed nc-FETs with amorphous indium-gallium-zinc oxide (a-IGZO) as the semiconductor material, Al2O3 as the dielectric, and poly(vinylidene fluoride-trifluoroethylene) (PVDF-TrFE) as the polymer ferroelectric. The printed nc-FETs demonstrate an extremely low subthreshold slope of ∼2.3 mV/decade at room temperature, which remains below the Boltzmann's limit for over 5 orders of magnitude of drain currents. Furthermore, the unipolar depletion-load-type inverters fabricated using n-type nc-FETs have demonstrated an extraordinary signal gain of 2691.

Design and implementation of an innovative single-phase direct AC-AC bipolar voltage buck converter with enhanced control topology

Direct AC–AC converters are strong candidates in the power converting system to regulate grid voltage against the perturbation in the line voltage and to acquire frequency regulation at discrete step levels in variable speed drivers for industrial systems. All such applications require the inverted and non-inverted form of the input voltage across the output with voltage-regulating capabilities. The required value of the output frequency is gained with the proper arrangement of the number of positive and negative pulses of the input voltage across the output terminals. The period of each such pulse for low-frequency operation is almost the same as the half period of the input grid or utility voltage. These output pulses are generated by converting the positive and negative input half cycles in noninverting and inverting forms as per requirement. There is no control complication to generate control signals used to adjust the load frequency as the operating period of the switching devices is normally greater than the period of the source voltage. However, high-frequency pulse width modulated (PWM) control signals are used to regulate the output voltage. The size of the inductor and capacitor is inversely related to the value of the switching frequency. Similarly, the ripple contents of voltage and currents in these filtering components are also inversely linked with PWM frequency. These constraints motivate the circuit designer to select high PWM frequency. However, the alignment of the high-frequency control input with the variation in the input source voltage is a big challenge for a design engineer as the switching period of a high-frequency signal normally lies in the microsecond. It is also required to operate some high-frequency devices for various half cycles of the source voltage, creating control complications as the polarities of the half cycles are continuously changing. This requires at least the generation of two high-frequency signals for different intervals. The interruption of the filtering inductor current is a big source of high voltage surges in circuits where the high-frequency transistors operate in a complementary way. This may be due to internal defects in the switching transistors or some unnecessary inherent delay in their control signals. In this research work, a simplified AC–AC converter is developed that does not need alignment of high-frequency control with the polarity of the source voltage. With this approach, high-frequency signals can be generated with the help of any analog or digital control system. By applying this technique, only one high-frequency control signal is generated and applied in AC circuits, as in a DC converter, without applying a highly sensitive polarity sensing circuit. So, controlling complications is drastically simplified. The circuit and configuration always avoid the current interruption problem of filtering the inductor. The proposed control and circuit topology are tested both in computer-based simulation and practically developed circuits. The results obtained from these platforms endorse the effectiveness and validation of the proposed work.

Research on controlling dual buck inverter in sliding mode based on buffered inductor

Abstract To overcome the problems of power transistor passthrough and switching loss in traditional bridge inverters, it is suggested to replace the conventional double Buck inverter with a double Buck inverter that has a buffer inductor placed in the center of the bridge arm with one that has a very modest inductance value. Firstly, a dual inductor single structure of the Buck inverter was examined, and based on this, a dual Buck inverter topology structure based on a buffer inductor was proposed. Then, the application of the sliding mode control strategy in dual Buck inverters based on buffer inductance was elaborated. Ultimately, tests were conducted to confirm the accuracy of the theoretical theory. The proposed dual Buck inverter based on buffer inductance solves the problem of low inductance utilization while retaining high reliability. Compared with single inductance DBI, it has smaller losses and lower control complexity, which has practical application value.

APPLICATION OF SOFT SWITCHING IN THREE-PHASE VOLTAGE INVERTERS OF TRACTIONAL ROLLING STOCK

Autonomous voltage inverters with PWM, which are used in electric drive systems with brushless motors, occupy an important place in the complex of electrical equipment of modern traction rolling stock of railways. The article presents the results of the research of the traction three-phase bridge voltage inverter with soft switching of power switches. Using the soft switching mode allows you to reduce the switching losses in the power transistors of the keys, increase the PWM frequency and improve other performance indicators of the converter. It is advisable to implement soft switching in the key transistors of the three-phase voltage inverter using soft switching nodes with fast-acting four-quadrant switches based on IGBT. It is proposed to consider the possibility of using transistor switches of a voltage inverter with capacitive non-dissipative snubbers at high PWM frequencies. For this purpose, a synthesis of the scheme and algorithm for the implementation of soft switching in a three-phase bridge voltage inverter with bipolar sinusoidal PWM with soft switching nodes with high-speed four-quadrant switches based on IGBT was performed. An analysis of the characteristics of the three-phase voltage inverter was carried out when using high-speed switches in the soft switching nodes to implement soft switching in the power transistors of the inverter switches.On the basis of the study, it is proposed to modernize the scheme of the soft switching unit in order to provide better preparation for the switching of the power transistors of the keys at large load currents. The improved soft switching unit includes low-voltage sources of constant voltage, which will compensate for energy losses in the recharging circuit of the snubber capacitors and contribute to the soft switching on of the power transistors of the voltage inverter keys. The performance test was carried out and the characteristics of the converter were analyzed when using a modernized soft switching node using simulation modeling in the MATLAB package.

On performance evaluation of high‐power, high‐bandwidth current measurement technologies for SiC switching devices

AbstractSilicon carbide (SiC) power metal‐oxide‐semiconductor field‐effect transistors (MOSFETs) switch at an unprecedented speed, even at high currents. For accurate dynamic characterization, current sensors must measure high currents at a high bandwidth. Moreover, at high switching speeds, parasitic impedances in the commutation loop become critical. To ensure high‐accuracy measurements, the current sensor insertion impedance must be minimal. Here, a two‐step current sensor evaluation method is proposed. This method serves the characterization and suitability assessment of high‐power, high‐bandwidth current sensors for fast‐switching applications using SiC power MOSFETs. Conducting a small‐ and a large‐signal transmission behaviour analysis separately results in holistic information about the current sensor behaviour in both time and frequency domain. The proposed method is validated using four commercially available current sensors that are widely used for SiC power MOSFET characterization. The work concludes transferring the knowledge derived in the conducted experiments to a practical, application‐oriented sensor selection guide.

Investigation into active‐gate‐driving performance and potential closed‐loop controller implementations for silicon carbide MOSFET modules

AbstractActive gate driving (AGD) is a promising concept for achieving high‐performance power transistor switching. This is particularly crucial for Silicon Carbide (SiC) MOSFETs since their inherently fast switching characteristics give rise to severe overshoots and oscillations which translate into increased levels of electromagnetic interference (EMI) emissions. In this paper, an AGD strategy using a single‐pulse applied during the switching transient is considered for a 1200 V 400 A SiC MOSFET module. The effect of single‐pulse timing, load current, and temperature on the switching performance is analyzed in detail. The radiated EMI reduction benefits are quantified by H‐field and E‐field probes. A conceptual closed‐loop AGD approach is presented and compared to open‐loop operation. For the transistor turn‐off case under full load current of 400 A, experimental results show that it is possible to reduce voltage overshoot by 43.3%, voltage and current oscillations by 69.7% and 52.2% respectively, and EMI by 76.6%, with a trade‐off in the switching energy by a relatively minor increase of 18.2%, compared to the conventional gate driving case. For the turn‐on case, current overshoot was reduced by 32.7%, EMI by 52%, voltage and current oscillations by 54.6% and 52.8%, respectively, with a penalty of 50.9% increase in the switching loss.

Soliton colliding in hybrid glass photonic crystal fiber for optical transistor switching

Soliton colliding in hybrid glass photonic crystal fiber for optical transistor switching

Improving Low-Frequency Digital Control in the Voltage Source Inverter for the UPS System

Today voltage source inverters (VSIs) operate with high switching frequencies (let us assume higher than 50 kHz) owing to the fast Si (Silicon) or SiC (Silicon Carbide) switching transistors. However, there are some applications, e.g., with slower switches (e.g., IGBT—Isolated Gate Bipolar Transistor) or when lower dynamic power losses are required when the switching frequency is low (let us assume about 10 kHz). The resonant frequency of the output filter is usually below 1 kHz. The measurements of Bode plots of the measurement traces of various microprocessor-controlled VSIs show that in this frequency range, the characteristics of these channels can be simply approximated through two or three switching periods delay. For the high switching frequency, it is not noticeable, but for the low frequency it can cause some oscillations in the output voltage. One of the solutions can be to use the predictor of the measured state variables based on the full-state Luenberger observer or the linear Kalman filter. Both solutions will be simulated in MATLAB/Simulink and the chosen one will be tested in the experimental VSI. The research aims to omit delays in the measurement channels for the low switching frequency by using the predictions for the measured state variables and finally increasing the gains of the controller to decrease the output voltage distortions.

CNT thin films based on epoxy mixtures: fabrication, electrical characteristics

The simple scaling of silicon transistors no longer ensures the advantages of high energy efficiency, driving research into nanotechnologies beyond silicon. Specifically, digital circuits based on carbon nanotube (CNT) field-effect transistors promise significant advantages in energy efficiency. However, the inability to perfectly control internal nanoscale defects and the variability of carbon nanotubes hinder the realization of very large-scale integrated systems. In this study, we investigated a novel method for fabricating transistors based on carbon nanotubes (CNTs) using epoxy mixtures, obtained the electrical properties of the transistors, and compared their microstructure and composition via the scanning electron microscopy. The carrier mobility on epoxy-based transistors was 28.87 cm²/V∙s, and the transistor switching frequency was 2.2 MHz. The samples exhibited electrical and physical stability over an extended period of time. The use of carbon nanotubes in epoxy resin as a conducting layer for transistors opens significant prospects in the field of electronics. The CNT-epoxy mixture technology allows for more flexible and rapid fabrication of thin-film transistors compared to classical methods. However, it is not appropriate to speak of a complete replacement; in this study, we present an alternative method for producing thin-film transistors, which may be of interest for specific purposes.

A Symmetric Sixth-Order Step-Up Converter with Asymmetric PWM Achieved with Small Energy Storage Components

This research explores an improved operation of a recently studied converter, the so-called two-phase sixth-order boost converter (2P6OBC). The converter consists of a symmetric design of power stations followed by an LC filter; its improved operation incorporates an asymmetric pulse width modulation (PWM) scheme for transistor switching, sometimes known as an interleaved PWM approach. The new operation leads to improved performance for the 2P6OBC. Along with studying the 2P6OBC, one of the contributions of this research is providing design equations for the converter and comparing it versus the interleaved (or multiphase) boost converter, known for its competitiveness and advantages; the single-phase boost topology was also included in the comparison. The comparison consisted of a design scenario where all converters must achieve the same power conversion with an established maximum switching ripple, and then the stored energy in passive components is compared. Although the 2P6OBC requires a greater number of components, the total amount of stored energy is smaller. It is known that the stored energy is related to the size of the passive components. Still, the article includes a discussion of this topic. The new operation of the converter offers more streamlined, cost-effective, and efficient alternatives for a range of applications within power electronics. The final design of the 2P6OBC required only 68% of the stored energy in inductors compared to the multiphase boost converter, and 60% of the stored energy in capacitors. This result is outstanding, considering that the multiphase boost converter is a very competitive topology. Experimental results are provided to validate the proposed concept.

Quantum Transport Simulations of Sub-60-mV/Decade Switching of Silicon Cold Source Transistors

Quantum Transport Simulations of Sub-60-mV/Decade Switching of Silicon Cold Source Transistors

Alleviation of the on-state dynamic conductance decline in a GaN high electron mobility transistor with heavy carbon doping

Carbon doping is a standard blocking-voltage-enhancing technique for commercial silicon substrate-based AlGaN/GaN power switching transistors, although the incorporation of carbon into GaN may deteriorate the dynamic on-state resistance (dy-R on) properties of the device. Commonly, researchers have believed that the greater the carbon doping, the greater the deterioration in dy-R on. Surprisingly, in this work, the opposite was observed: the dy-R on value decreased as the carbon concentration increased, particularly when the density exceeded several 1017 cm−3. This phenomenon is explained by the effect of electric field-induced band-to-band electron tunneling into the two-dimensional electron gas (2DEG) conduction channel, originating from the ionization of acceptor-like nitrogen site carbon atoms (CN) in the device off-state with large drain bias. Simulation data indicated that negatively ionized CN may generate a much larger electric field in samples with higher carbon doping, which may induce a narrower 2DEG back energy band barrier that increases the possibility of electron band-to-band tunneling.

Моделирование влияния электромагнитных полей на микросхемы

The article examines the influence of electromagnetic fields on radiation effects in microcircuits, describes the influence of electromagnetic fields depending on the distance from the center of the explosion, and evaluates the degree of protection of microcircuits. Assessments of the impact of electromagnetic fields created by gamma radiation on CMOS microcircuits are considered, the physical process, a mathematical model of the occurrence of leakage current, charge loss, transistor switching speed and electronic mobility are described. The methods of protecting CMOS semiconductors from the effects of electromagnetic fields are considered: shielding, reducing the power and frequency of radiation, and compensation for the effects. Both the physical basis and the mathematical model of the parameters for shielding are considered: attenuation coefficient and shielding efficiency. The main method of protecting microcircuits from electromagnetic fields is determined using shielding, reducing the power and frequency of radiation, as well as compensating for exposure. The article describes the mathematical and algorithmic models on the basis of which a computer model was built to assess the impact of the electromagnetic field on CMOS semiconductors. The assessment of the reliability of the chip security assessment is based on a computer experiment built using a program written in the C# programming language. The result was data from an analysis of protection from the effects of an electromagnetic field on CMOS semiconductors for distances from the epicenter of the explosion at a distance of 10 to 100 km with a step of 10 km.

Bioinspired carbon nanotube-based nanofluidic ionic transistor with ultrahigh switching capabilities for logic circuits.

The voltage-gated ion channels, also known as ionic transistors, play substantial roles in biological systems and ion-ion selective separation. However, implementing the ultrafast switchable capabilities and polarity switching of ionic transistors remains a challenge. Here, we report a nanofluidic ionic transistor based on carbon nanotubes, which exhibits an on/off ratio of 104 at operational gate voltage as low as 1 V. By controlling the morphology of carbon nanotubes, both unipolar and ambipolar ionic transistors are realized, and their on/off ratio can be further improved by introducing an Al2O3 dielectric layer. Meanwhile, this ionic transistor enables the polarity switching between p-type and n-type by controlled surface properties of carbon nanotubes. The implementation of constructing ionic circuits based on ionic transistors is demonstrated, which enables the creation of NOT, NAND, and NOR logic gates. The ionic transistors are expected to have profound implications for low-energy consumption computing devices and brain-machine interfacing.

Design and Fabrication of Switched Reluctance Motor for Energy Efficient Operation by Minimizing Torque Ripple

Around the world, motor is consuming more than 40% of the total-generated electrical energy. Accordingly, energy efficient electrical drives are the needs of the hour. The Switched Reluctance Motor (SRM) is more energy efficient than other kinds. Since SRM has a rugged structure, it has inherent fault tolerance characteristics and is cost-effective than synchronous and induction machines. Nevertheless, the application of such a motor is limited due to low torque density, torque ripples and power losses because of control circuit. In this research work, the author proposed a novel-designed SRM, which is achieved by optimizing stator and rotor pole arc. Alongside, a novel control circuit, which has single transistor, is proposed. The modification of stator and rotor pole arcs assists in the reduction of the torque ripple. The stator pole arc is modified from 32 degree to 36 degree, and the rotor pole arc is modified from 30 degree to 28 degree. Thus, the torque ripple is reduced from 3.25 to 2.92 Nm, and thus, the useful torque is increased from 4.94 to 5.2 Nm. Furthermore, a single transistor switching device is used instead of the conventional one with four switches. Hence, energy loss on the control circuit is significantly reduced. From the experimental analysis, it is found that, with-pole-arc modified SRM has higher efficiency than the one without it.

Integrated 2T1C pixel circuit with a-Si TFT and NMOS for active matrix mini-LED displays

The 2T1C pixel driver circuit for mini-LED direct display has been proposed, which separates the switching transistor and the driver transistor from the same display substrate, replaces the driver transistor with n-metal oxide semiconductor (NMOS), and combines printed circuit board substrate and thin-film transistor (TFT) substrate to improve the driving capability of the circuit. The NMOS was soldered with mini-LEDs simultaneously onto a substrate which connects to the a-Si TFT array. Two driving modes for a 32-level gray-scale display panel were investigated to compare the voltage-current and optical characteristics. The results demonstrated that the drain-driving mode is better suited for high brightness and high-power display application scenarios as it supports higher-driven currents, but the source-driving mode is more appropriate for precision gray-scale applications due to the higher current linearity of the mode.