Switching Capability Research Articles

Highly Efficient Switching Operation of 1.2 kV-Class SiC SWITCH-MOS

A 1.2 kV silicon carbide (SiC) SBD-wall-integrated trench metal oxide semiconductor field effect transistor (MOSFET) (SWITCH-MOS) exhibits potential for solving body-PiN-diode-related problems such as bipolar forward degradation and switching losses among relatively low breakdown voltage 1.2 kV-class SiC MOSFETs. In this study, dynamic characteristics and switching losses of the SWITCH-MOS and conventional MOSFET are compared. The results demonstrate that the SWITCH-MOS exhibits smaller turn-on and reverse recovery losses than a conventional MOSFET at high temperatures. Ruggedness performances such as short circuit and unclamped inductive switching capabilities were evaluated.

Design principles of dual-functional molecular switches in solid-state tunnel junctions

Molecular electronics has improved tremendously over the past 20 years, but it remains challenging to develop molecular switches that operate well in two-terminal tunnel junctions. Emerging technologies demand multi-functional junctions that can switch between different operations within a single molecule or molecular monolayer. Usually the focus is placed on molecules that shift the junctions between high and low conductance states, but here we describe molecular junctions with dual-functional switching capability. We discuss the operating mechanism of such switches and present examples of “two-in-one” junctions of a diode placed in series with an additional switch, which can operate either as an electrostatic or a memory on/off switch. We propose guidelines for future designs of such dual-function molecular switches and provide an outlook for future directions of research.

The impact of balanced agile project management on firm performance: the mediating role of market orientation and strategic agility

PurposeThis study aims to examine the impact of balanced agile project management (balanced APM) on firm performance through the mediating role of market orientation and strategic agility of medium and large telecommunication technology providers in Indonesia.Design/methodology/approachResearch data was collected from the executive management of telecommunication technology providers in Indonesia via a questionnaire survey to obtain 150 valid questionnaires for analysis. This study analyzed the overall model fit through confirmatory factor analysis and causal relationships through structural equation modeling.FindingsThe results indicate that market orientation mediates the link between balanced APM and strategic agility and that strategic agility mediates the link between market orientation and firm performance.Research limitations/implicationsThe choice of single telecommunication industry in a single country, Indonesia, provides a limitation on external validity. It is, therefore, suggested to extend the research efforts to other industry sectors in multi-country environments.Originality/valueThis study extends the knowledge about agile project management by embracing balancing control enforcement and tests it empirically. This study also re-conceptualizes strategic agility to embrace business partner switching capability and market orientation to embrace the inter-partner coordination dimension. Finally, the results highlight that agile project management needs to be framed by market orientation to create higher value for customers. However, market orientation alone is not enough and that the organization requires strategic agility to achieve firm performance.

Numerical modeling of integrated electro-optic modulators based on mode-gap shifting in photonic crystal slab waveguides containing a phase change material

This paper presents novel designs and simulation results of electro-optic modulators in integrated silicon photonics platforms. The electro-optic modulators described in this paper are based on the modulation of the photonic bandgap in a silicon photonic crystal slab waveguide, consisting of a phase change material (germanium selenide) sandwiched in between silicon layers. Three-dimensional finite difference time domain (FDTD) modeling is employed to simulate two configurations of electro-optic modulators based on mode-gap shifting in photonic crystal slab waveguides—one that is designed for operation with the transverse electric (TE) polarization of light and the other for the transverse magnetic (TM) polarization. When the electric field is applied across the germanium selenide layer surrounded by doped silicon layers, there is a change of phase of the germanium selenide layer. A large refractive index contrast between the two phases of the germanium selenide layer—i.e., between the amorphous phase and the crystalline phase—on application of the electric field is responsible for shifting of the mode gap in the dispersion characteristics of the PhC slab waveguide. Our results show excellent performance of the electro-optic modulators in terms of the high On/Off extinction ratio ( > --> 37 d B in the TE configuration and > --> 28 d B in the TM configuration), broadband switching capability ( ∼ 100 n m ), low insertion loss in the On state ( < 2 d B ), high range of tunability (by changing the lattice constant and radius of air holes), and low operating voltage ( < 4 V ). The proposed devices can be used as electro-optic modulators in future nanoscale photonic integrated circuits.

Optical transport for Industry 4.0 [Invited

Industry 4.0 represents a new industrial revolution that will dramatically change the landscape in many sectors, including manufacturing and logistics. Robotics, machine intelligence, and new forms of connectivity are key ingredients of this paradigm. 5G mobile networks are expected to play a crucial role, supporting a lower cost per transported bit in air and a lower latency compared with 4G. 5G radio ensures different performance levels in very heterogeneous coverage situations, including a mix of indoor and outdoor contexts. Mobile network evolution requires new transport networks to address the new challenging requirements: increasing transmission capacity, compatibility with latency-critical applications, significantly reduced cost with respect to conventional metro network segments, lower energy consumption, and, in some cases, switching capabilities. Optical communications and networking will play a key role in these new transport scenarios, where tailored transmission techniques and network architectures are needed. This paper discusses the requirements and challenges that Industry 4.0 scenarios pose to optical communications and networking architectures. Performance of optical transmission schemes, tailored to support these new radio access networks, are detailed and benchmarked. A network test bed, focused on transport for vertical use cases, is described. Experimental results demonstrate the compliance of the proposed optical transport network with a latency-critical cloud robotics application, which presents industry-grade connectivity needs.

Multilevel Switching-Mode Operation of Finite-Set Model Predictive Control for Grid-Connected Packed E-Cell Inverter

In this article, we propose a modified finite-set model predictive control (M-FS-MPC) for multilevel switching-mode operation of grid-connected nine-level packed E-cell (PEC9) inverter. With a single-dc source, six power switches, back-to-back-connected switches as bidirectional and two capacitors horizontally extended, PEC9 inverter topology has remarkably reduced the components count. Packed E-cell (PEC) prominent feature has the capability of switching among different multilevel voltages: nine-, seven-, or five-level under faulty switch cases without any structural modification and only if the controller is appropriately designed. M-FS-MPC is proposed to operate the grid-connected PEC with the multilevel switching mode under bidirectional switch fault operation. Switching among five-, seven-, or nine-level voltages is attained by proper dc capacitors' voltages regulation, whereas the desired current injection with low total harmonic distortion (THD) and requested power factor for addressing grid connectivity applications is guaranteed. The system discrete model is developed and the experimental results verify the performance and robustness of M-FS-MPC in targeting the capability of PEC multilevel switching-mode operation and grid connectivity requirements in both steady and transient states.

MXene Ti3C2Tx as a passive Q-switcher for erbium-doped fiber laser

Abstract A layered metal carbide/nitride known as MXene owns superior optical properties such as high optical damage tolerance, fast-optical switching capability, and excellent nonlinear transmittance property, making it a favourable SA device for a fiber laser cavity. We synthesis the MXene Ti3C2Tx using selective etching and developed two SA devices, which were MXene-film and MXene D-shaped fiber (MXene-DS). The optical properties of the as-prepared SA devices were investigated, and MXene-DS shows a significant improvement in terms of nonlinear transmittance with 3% modulation depth and 58.5% nonlinear loss. The SA devices were then incorporated into an EDFL and generated Q-switched lasers at the threshold pump power of 44 mW for MXene-film and 81 mW for MXene-DS. The MXene-film initiates a stable Q-switched with a minimum pulse width of 2.31 µs whereas, MXene-DS exhibit a pulsed laser with a minimum pulse width of 2.58 µs. MXene-DS shows excellent pulse stability at a high pumping power, making it a suitable SA device for EDFL.

Unified Voltage Balancing Feedforward for Three-Level Boost PFC Converter in Discontinuous and Critical Conduction Modes

This brief presents a unified voltage balancing feedforward (UVBFF) for three-level boost (TLB) power-factor-correction (PFC) circuit in discontinuous and critical conduction modes. In general, the topology in both modes puts emphasis on low-cost system. Thus, electrolytic capacitors with wide-tolerance are commonly used at outputs and voltage unbalance is inevitable even under symmetric operations of two boost cells. In this brief, three-level switching capability of TLB PFC is introduced and asymmetric on-time feedforward for main switches is proposed. The proposed UVBFF can be realized by a single equation and harmonized with conventional feedback voltage-loop so that easy implementation is the key merit. The effectiveness of UVBFF is proven by analyses and experimental results.

Extended ZCS Region of AAC-HVDC Systems Through On-Load Tap Changer Coordination

Arm inductances and the operation of two arms of a phase leg in an alternate arm converter (AAC) can lead to hard-switching of the director switches (DSs) during steady-state operation, increasing voltage stresses across the DSs. The DS voltage stress also depends on the magnitude of the interrupted arm current, which, in turn, depends on the output active/reactive power. Hard-switching of the DSs limits the operating region of the AAC. This article characterizes the zero-current switching (ZCS) capability of the AAC and proposes extended ZCS operation in steady state for HVDC applications. This is achieved by coordinating the AAC operating point and the transformer on-load tap changer (OLTC). The coordinated operation utilizes the tap positions of the HVDC transformer effectively to extend the ZCS operating region with no added effort on circulating current control. Results based on an AAC-HVDC transmission system demonstrate the effective coordination of the transformer OLTC and the converter operating point to achieve extended ZCS performance.

Analogue switches made from boron nitride monolayers for application in 5G and terahertz communication systems

Hexagonal boron nitride (hBN) has a large bandgap, high phonon energies and an atomically smooth surface absent of dangling bonds. As a result, it has been widely used as a dielectric to investigate electron physics in two-dimensional heterostructures and as a dielectric in the fabrication of two-dimensional transistors and optoelectronic devices. Here we show that hBN can be used to create analogue switches for applications in communication systems across radio, 5G and terahertz frequencies. Our approach relies on the non-volatile resistive switching capabilities of atomically thin hBN. The switches are composed of monolayer hBN sandwiched between two gold electrodes and exhibit a cutoff-frequency figure of merit of around 129 THz with a low insertion loss (≤0.5 dB) and high isolation (≥10 dB) from 0.1 to 200 GHz, as well as a high power handling (around 20 dBm) and nanosecond switching speeds, metrics that are superior to those of existing solid-state switches. Furthermore, the switches are 50 times more efficient than other non-volatile switches in terms of a d.c. energy-consumption metric, which is an important consideration for ubiquitous mobile systems. We also illustrate the potential of the hBN switches in a communication system with an 8.5 Gbit s–1 data transmission rate at 100 GHz with a low bit error rate under 10−10. Resistive switching in atomically thin sheets of hexagonal boron nitride can be used to create analogue switches for applications in communication systems across radio, 5G and terahertz frequencies.

Sub-nanosecond-speed frequency-reconfigurable photonic radio frequency switch using a silicon modulator

Radio frequency (RF) switches are essential for implementing routing of RF signals. However, the increasing demand for RF signal frequency and bandwidth is posing a challenge of switching speed to the conventional solutions, i.e., the capability of operating at a sub-nanosecond speed or faster. In addition, signal frequency reconfigurability is also a desirable feature to facilitate new innovations of flexible system functions. Utilizing microwave photonics as an alternative path, we present here a photonic implementation of an RF switch providing not only the capability of switching at a sub-nanosecond speed but also options of frequency doubling of the input RF signals, allowing for flexible output waveforms. The core device is a traveling-wave silicon modulator with a device size of 0.2 mm × 1.8 mm and a modulation bandwidth of 10 GHz. Using microwave frequencies, i.e., 15 GHz and 20 GHz, as two simultaneous RF input signals, we experimentally demonstrated their amplitude and frequency switching as well as that of the doubled frequencies, i.e., 30 GHz and 40 GHz, at a switching frequency of 5 GHz. The results of this work point to a solution for creating high-speed RF switches with high compactness and flexibility.

Push-pull microring-assisted space-and-wavelength selective switch.

We introduce a novel design of a space-and-wavelength selective switch based on microring-assisted Mach-Zehnder interferometers. Multiple pairs of overcoupled microring resonators are incorporated as efficient and narrowband phase shifters and are driven in push-pull scheme. We design and demonstrate a 2×2×2λ elementary switch block with full spatial and spectral switching capabilities. The switching device's cross talk suppression and extinction ratio both exceed 21 dB. We measure over 75 GHz optical bandwidth per channel and less than 1.5 dB power penalty at 10-9 BER when two 32 Gbps on-off keying signals are loaded simultaneously. This new class of switching elements can further enable compact and high-performance space-and-wavelength selective switch fabrics without the need for wavelength (de)multiplexers or parallel switching planes.

Efficient energy storage and fast switching capabilities in Nd-substituted La2Sn2O7 pyrochlores

Pyrochlore materials show intensive potential for various everyday applications owing to their highly stable structure with tunable lattice parameters. Energy storage tunability and switching capabilities of these materials can further be improved using suitable cationic substitutions. In this context, we report a series of Nd-substituted lanthanum stannate (La2−xNdxSn2O7) pyrochlores, prepared using sol-gel auto-combustion method. It has been observed that Nd-substitution finely tuned the lattice parameters of parent compound without compromising its cubic phase stability. The gradual replacement of La with Nd resulted in well crystalline grains, adopting diamond and cubic like shapes. Ferroelectric nature, electrical conductivity, switching charge density and normalized capacitance, which are among the key features of a ferroelectric material, were also analyzed. The increasing difference between saturation and remanent polarizations, especially when x ≥ 1.2, make them a potential candidate for energy storage devices. The maximum value of energy density efficiency i.e. more than 60% was observed for pure Nd2Sn2O7. In addition, low switching charge density makes them prominent for fast switching applications. Magnetic response revealed their superparamagnetic behavior with small remanence and low coercivity (~30 Oe), which exposed their potential for biomedical applications provided its particle size is controlled.

Impact of the forming and cycling processes on the electrical and physical degradation characteristics of HfO2-based resistive switching devices

In this work, electrical and physical analysis of filamentary-type Ni/HfO2/n+-Si resistive random access memory devices were carried out with the aim of evaluating the microstructural changes occurring in the oxide layer and metal electrode after the initial forming step and subsequent switching cycles. To this end, Scanning Electron Microscopy analysis of the top oxide surface after Ni removal was performed. The obtained images show the generation of small hillocks and defects in the active area of the device caused by current-induced Joule heating effects. Material analysis of these hillocks reveals that they are a Ni-based compound. The size and morphology of the generated damage is shown to depend both on the switching polarity and compliance used to limit the current flow during the formation of the conductive filament. In addition, the damage induced in the structure not only depends on the current magnitude reached in the set process, but also on the maximum current reached during the reset phase, with both current levels severely affecting the long-term switching capability of the devices.

Sensing and switching capabilities of a graphene-based perfect dual-band metamaterial absorber with analytical methods

In this paper, the simultaneous sensing and switching performance of a graphene-based plasmonic dual-band absorber in the terahertz region has been demonstrated and investigated. Due to the high confinement of graphene surface plasmons and the hydrophobic nature of graphene, the structure can be used as a refractive index sensor in biomedical applications such as detection of impurities of water, cancer cells, and STMV virus. The simulation results show an ultrahigh sensitivity of 360 THz/RIU and figure of merit of 654.54 R I U − 1 . Moreover, variation of the graphene chemical potential leads to a switching function between the perfect absorption and total reflection states, with the high extinction ratio of 12.15 dB and ultrafast response time of 1.5 ps. Two analytical methods of equivalent circuit model and transmission matrix have been used to validate the suggested idea of the proposed graphene-based structure. We have shown that there is a good agreement between the theoretical and simulation results. The specifications of our suggested structure are tunability, ultrahigh sensitivity, high extinction ratio, ultrafast response time, and simple design, which pave the ways for design and implementation of other multi-application terahertz plasmonic structures based on graphene in the future.

Analytical Methods of Equivalent Circuit Model and Transmission Matrix for a Plasmonic Switch with Sensing Capability in Near-Infrared Region

In this paper, the simultaneous switching and sensing capabilities of a compact plasmonic structure based on a conventional rectangular hole in a silver film are proposed and investigated. The proposed structure has ultrahigh sensitivity up to 3000 nm/RIU and high figure of merit of 170 RIU−1. Also, the simulation results show the potential of the presented refractive index sensor to detect malaria infection, cancer cells, bacillus bacteria, and solution of glucose in water. Simultaneously, by changing the incident lightwave polarization, the structure behaves like a plasmonic switch, which has high extinction ratios of 15.81, 31.20, and 25.03 dB at three telecommunication wavelengths of 850, 1310, and 1550 nm, respectively. The ultrafast response time of 20 fs is achieved for the wideband application of the switching capability at the wavelength range of 1056 to 1765 nm. Moreover, the equivalent circuit model and transmission (ABCD) matrix methods are derived to validate the simulated results. Simple design, good agreement between the numerical and analytical results, biomedical applications, ultrahigh sensitivity, and ultrafast performance of the proposed structure help this idea to open up paths for design and implementation of other multi-application plasmonic devices in near-infrared region. To the best of our knowledge, the mentioned analytical methods have not been studied former at near-infrared wavelengths. Therefore, the achievements could pave the way for verifying the simulation results of plasmonic nanostructures in future investigations.

Sensing and switching capabilities of a tunable GST-based perfect absorber in near-infrared region

In this paper a GST-based perfect absorber is investigated for sensing applications. The simulation results show the high sensitivity and figure of merit of 900 nm per refractive index unit (RIU) and 15 RIU−1, respectively. The sensing parameters are also studied for different biomedical applications such as detection of glucose in water, malaria infection, bacillus bacteria, and cancer cells. The phase change material GST makes the structure tunable and switchable by changing the phase through different annealing temperatures. By changing temperature, the optical characteristics of GST are altered and so the perfect absorption can be tuned at different near-infrared wavelengths. Moreover, the sweep between the amorphous and crystalline states of GST results in switching capability with the high extinction ratio of 13.97 dB at λ = 1724 nm. Therefore, the perfect tunable absorber supports our new idea of multi-application plasmonic devices with two capabilities of sensing and switching, simultaneously. Also, the E-field distributions and analytical method of equivalent circuit model are utilized to verify the simulation results and demonstrate a better insight of the proposed structure performance. The polarization independency of the proposed structure, tunability, good sensing and switching performances are some other benefits of our proposed structure, which can pave the way for development of new investigations about the phase change material applications in plasmonic studies.

Hybrid modulation strategy of three-phase dual-active-bridge converter to improve power conversion efficiency under light load conditions in LVDC applications

A hybrid control strategy for the three-phase dual-active-bridge (3P-DAB) converter of LVDC applications is presented to improve the power conversion efficiency under light load conditions. The 3P-DAB converter is an attractive topology for high-power applications such as railway traction and aircraft due to its inherent the zero voltage switching (ZVS) capability and reduction of conduction loss due to an interleaved structure with seamless bi-directional power transitions. However, conventional phase shift modulation (PSM) applied to a 3P-DAB converter has disadvantages such as ZVS failure under light load conditions. In this paper, an asymmetrical pulse width modulation is inserted into PSM to replace the existing modulation algorithm of a 3P-DAB converter with a simple control approach. In the proposed control, the transferred power can be calculated according to the mode changes. In addition, the soft switching area of the power switches can be expanded by the proposed hybrid control strategy. Finally, experimental results validate the proposed hybrid modulation strategy using a 3-kW prototype 3P-DAB converter.

Search for Ferroelectric Binary Oxides: Chemical and Structural Space Exploration Guided by Group Theory and Computations

The presence of bistable polarization states along with accessible switching capabilities make ferroelectrics an ideal candidate for a variety of applications. Although many conventional ferroelect...

Initial states and analog switching behaviors of two major tantalum oxide resistive memories

A systematic study was performed to understand the two major operation modes, valence change memory (VCM) and electrochemical memory (ECM), of tantalum oxide resistive memory, which were categorized by the type of conductive filament. The tantalum oxide insulator layer was predictably fabricated to modify the pristine oxygen-vacancy concentration in the insulator layer, where tantalum and copper top electrodes were used to achieve VCM and ECM modes. The distinguishable characteristics of the initial state and analog resistive switching operation revealed the prerequisites for switching capabilities and demonstrated the effects of oxygen vacancies in the two switching modes.