Diode Voltage Research Articles

Vertical GaN diode BV maximization through rapid TCAD simulation and ML-enabled surrogate model

In this paper, two methodologies are used to speed up the maximization of the breakdown voltage (BV) of a vertical GaN diode that has a theoretical maximum BV of ∼ 2100 V. Firstly, we demonstrated a 5X faster accurate simulation method in Technology Computer-Aided-Design (TCAD). This allows us to find 50 % more numbers of high BV (>1400 V) designs at a given simulation time. Secondly, a machine learning (ML) model is developed using TCAD-generated data and used as a surrogate model for differential evolution optimization. It can inversely design an out-of-the-training-range structure with BV as high as 1887 V (89 % of the ideal case) compared to ∼ 1100 V designed with human domain expertise.

A high efficiency and high power L-band relativistic magnetron with all-cavity extraction

Relativistic magnetron (RM) is a promising high-power microwave source, whose advantages include high efficiency, high power, and compact configuration. Enhancing power efficiency and output power are the most important two development directions for RM. Based on the two targets, a high efficiency and high power RM is presented and investigated numerically and experimentally in this paper. When the diode voltage is 485kV, the beam current is 6.9kA, and the magnetic field is 0.34T, and high power microwave is generated with the power of 1.35 GW, frequency of 1.47GHz, and power efficiency of 40.3% in the experiments.

A 500kV, 10kA, 40ns coaxial Marx generator pulser for cable fed flash x-ray system.

Flash x-ray (FXR) systems are used for dynamic radiography. Depending on the speed of the object, these systems typically require a very short pulse duration (∼25ns) for image acquisition without motion blur. The conventional Marx generators with zigzag discharge paths result in higher inductance; hence, they do not meet the requirement of shorter pulse duration (30-40ns) and low impedance (40-60 Ω) simultaneously. A coaxial Marx generator has been designed and developed, which is capable of generating 500kV peak voltages and 10kA peak current within a 40ns pulse duration. The CST simulation of the coaxial Marx generator has been carried out to validate the design parameters. The FXR electron beam diode is powered by this Marx generator. Experiments were carried out to measure the x-ray parameters like pulse width, source size, x-ray energy spectrum, penetration depth, and cone angle. The maximum measured x-ray dose was 62 mR at 1m distance from the source window. The x-ray radiograph demonstrates a penetration depth of 32mm in steel kept at 2.5m distance from the source for 500kV diode voltages.

A Single-Switch High-Voltage-Gain DC–DC Converter With Reduced Switch Voltage Stress

In this article, a novel single-switch high-voltage-gain dc–dc converter is presented. The proposed converter is operated with continuous input current, and the voltage stress across the power switch is lower compared to the competitive high-voltage-gain topologies. Hence, a lower rating active switch can be selected for the proposed configuration to achieve reduced conduction losses due to its low <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> -state resistance of the switch. The leakage energy of the coupled inductor is effectively recycled to the load through the voltage multiplier used in the topology. The voltage stress across the power diode at the output side is low, and hence, there is an improvement in the output-side reverse recovery performance. Moreover, the proposed topology has reduced aggregate diode voltage stress. A detailed comparative study consisting of steady-state analysis, working principle, and efficiency and reliability evaluation of the proposed converter for the continuous conduction mode is presented. The proposed concept is verified through extensive simulation studies and from the measured results from the experimental prototypes.

An X-band high-power and high-efficiency coaxial relativistic klystron oscillator with four-gap buncher and three-gap extractor

Because of the scaling invariance, the over-mode ratio of the coaxial resonator can be increased to increase the power handling capability. However, as the over-mode ratio increases, the characteristic impedance and external quality factor decrease, which causes the modulation of the electron beam to be weakened. Moreover, when the output microwave power increases, the double-gap output cavity will suffer from severe radio frequency breakdown. Therefore, an X-band high-power and high-efficiency coaxial relativistic klystron oscillator with a four-gap modulation cavity and a three-gap extraction cavity is proposed. First, a four-gap modulation cavity can increase the modulation depth of the electron beam to improve the beam-wave conversion efficiency. The operating mode of the modulation cavity is the 3π/4 mode of the coaxial TM01 mode. Second, a three-gap extraction cavity is adopted to enhance the microwave extraction energy and reduce the RF field strength. The simulation results show that when the diode voltage is 650 kV, the beam current is 15.4 kA, and the guiding magnetic field is 0.48 T, the device outputs a microwave power of 4.2 GW, a frequency of 8.4 GHz, and an efficiency of 42%.

Design of Programmable Transmitarray Antenna With Independent Controls of Transmission Amplitude and Phase

A design method of programmable transmitarray with independent controls of transmission amplitude and phase is proposed in C-band. The unit cell with cascaded structures mainly consists of four parts, including the receiving antenna, reconfigurable attenuator with PIN diodes, reconfigurable phase shifter with varactors and transmitting antenna. Correspondingly, various manipulations of spatial electromagnetic (EM) fields are achieved by varying the bias voltages of PIN diodes and varactors in the transmitarray. The fabricated unit cell is measured in a standard waveguide, and the whole array with 8*8 unit cells is measured with two horns for calibration of the programmable EM features. The experimental results show that the transmission magnitude can range from -16 dB to -3.6 dB and the transmission phase achieves 270-degree coverage independently under the 16-bit programmable control. To further exhibit the capability and functionality of the proposed transmitarray, the waveform engineering of adaptive beamforming and power-allocation beamforming are separately realized in the experiment. The measured results have good agreements with our theoretical calculations, verifying the validity of our design method.

Multilevel inverter with active clamping diodes for energy efficiency improvement

Multilevel inverters can replace commonly used two-level inverters for three-phase electrical drives. In this lowvoltage range new wide-bandgap power switches (SiC MOSFET, GaN FET) are available. In the four-, five- and sevenlevel inverters, the majority of the power losses are caused by the threshold voltage of the clamping diodes. The new idea is the replacement of the clamping diodes by active switches, since they only have low on-resistance in the forward direction. In this case freewheeling paths of the clamping diodes would have to be actively switched. However, the control signals for the clamping switches can be generated by logic operations from the control signals for the main switches. The use of active clamping switches has significant potential to reduce semiconductor losses, but requires the development of wide-bandgap power semiconductors with reverse blocking capability. At nominal motor operation point of the 5.5 kW induction motor a loss reduction of 56 % between active clamping switches and clamping diodes is possible. With a higher number of inverter levels, the size of the motor filter can be reduced by about 70 % and also the losses can be reduced by 73 %.

Achieving low driving voltage and high-efficiency afterglow organic light-emitting diodes through host–guest doping

Achieving afterglow organic light-emitting diodes (OLEDs) that exhibit the organic ultralong room temperature phosphorescence (OURTP) emission after switching off the applied voltage is highly attractive. However, it is difficult to obtain appropriate emitting layers that are of excellent charge transport ability and OURTP properties simultaneously to fabricate highly efficient afterglow OLEDs. Here, we report an easy but effective strategy to construct afterglow OLEDs via host–guest doping by adopting the excellent carrier transporting materials as rigid host and the commendable OURTP emitters as guest. The resultant green afterglow OLEDs exhibit the state-of-the-art maximum external quantum efficiency, luminance, and OURTP lifetimes of up to 1.47%, 743 cd m−2, and 356 ms, respectively, with the low turn-voltage of 4.4 V. Due to the inherent stable afterglow properties and outstanding carrier transport ability of the emitting layer, the OLEDs show admirable afterglow emission stability with the intensity and lifetimes keeping almost the same for more than ten repeated voltage pulses. The current work paves the way to develop highly efficient and stable afterglow OLEDs by host–guest doping.

Experimental research based on a C-band compact transit-time oscillator with a novel diode loading an embedded soft magnetic material and shielding structure

In order to reduce the external magnetic field and improve the conversion efficiency of high-power microwave generation devices with low external magnetic field, a novel diode with an embedded soft magnetic and shielding structure is proposed. The soft magnetic material is designed to enhance the local magnetic field in the diode region. Moreover, the diode applies a shielding structure which can reduce the radial electric field. From simulation research, it is found that the emission and transmission quality of the electron beam with low magnetic field is greatly improved when loading this diode. Through simulation research, it is verified that the diode can increase the conversion efficiency of the transit-time oscillator (TTO) from 30% to 36.7%. In our experimental study, under the conditions of a diode voltage of 540 kV and a current of 10.5 kA, the output microwave power is 1.51 GW when loading the novel diode and the microwave frequency is 4.27 GHz when an external guiding magnetic field of 0.3 T is applied. The corresponding conversion efficiency is improved from 20.0% to 26.6%, which is 6.6% higher than that of a device loaded with a conventional diode. Our experiments have verified that this novel diode can effectively improve the conversion efficiency of high-power microwave sources operating with low magnetic field, and contribute to the miniaturization and compactness of high-power microwave devices.

Design of vertical diamond Schottky barrier diode with a novel beveled junction termination extension

In this paper, vertical diamond Schottky barrier diode with a beveled junction termination extension is designed by using Silvaco TCAD. We firstly investigate the effects of the pn junction termination extension on the electrical performances to optimize the doping concentration. In addition, the beveled structure with an angle of 45° decreases the current conduction path slightly, but it also enhances the reverse breakdown voltage effectively. By combining the junction termination extension and beveled structures, a new termination structure is proposed for the vertical diamond Schottky barrier diode. Under forward bias, the depletion region introduced by the pn junction hindrances the current conduction slightly and increases the on-resistance. However, the electric field crowding phenomenon is alleviated drastically under reverse bias, resulting in a more uniform electric field distribution and high breakdown voltage. Therefore, the beveled junction termination structure is promising to balance the on-resistance and the reverse breakdown voltage of the diamond Schottky barrier diode.

Self-powered silicon PIN neutron detector based on triboelectric nanogenerator

Silicon PIN neutron detectors play an important role in nuclear science with advantages such as small size, light weight, low cost, and mature manufacturing process. This paper proposes a self-powered neutron detection system based on a triboelectric nanogenerator (TENG) and silicon PIN diode for the first time. The proposed environmentally efficient and low-cost TENG is connected to the detector through a rectifier bridge circuit. When the TENG powered silicon neutron detector is irradiated, the PIN diode generates defects in the silicon body, which leads to a decrease in the lifetime of excess carriers. The neutron dose can be measured by monitoring the change of the terminal voltage of the PIN diode.

The lock-on effect and collapsing bipolar Gunn domains in high-voltage GaAs avalanche p-n junction diode

We present experimental evidence and physics-based simulations of the lock-on effect in high-voltage GaAs avalanche diodes. The avalanche triggering is initiated by steep voltage ramp applied to the diode and in-series 50 Ω load. After subnanosecond avalanche switching the reversely biased GaAs diode remains in the conducting state for the whole duration of the applied pulse (dozens of nanoseconds). There is no indication of the p-n junction recovery that is commonly expected to develop on the nanosecond scale due to the drift extraction of non-equilibrium carriers. The diode voltage keeps a constant value of ∼70 V much lower than the stationary breakdown voltage of 400 V. Numerical simulations reveal that the conducting state is supported by impact ionization in narrow high-field collapsing Gunn domains as well as in quasi-stationary cathode and anode ionizing domains. Collapsing Gunn domains spontaneously appear in the dense electron-hole plasma due to the negative differential mobility of electrons in GaAs. The effect resembles the lock-on effect of GaAs bulk photoconductive switches but is observed in reversely biased p-n junction diode switched by a non-optical method.

Effect of Microwave Leakage on Backward Current in an X-Band Dual-Mode RBWO Packaged With Permanent Magnet

In this article, the effect of microwave leakage into the diode region on the suppression of backward current in a relativistic backward wave oscillator (RBWO) operating at low magnetic field is investigated by the theoretical analysis, particle-in-cell (PIC) simulation, and experiments. The theoretical results show that some backward electrons are absorbed by the cathode holder due to microwave leakage, and as the microwave power increases, the microwave frequency increases, and the guiding magnetic field decreases, it will promote the absorption of electrons. The PIC simulations based on the first principle reveal that the leakage microwave partially suppresses the backward current and the suppression is enhanced when the incidence TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">02</sub> is dominant. In the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${X}$ </tex-math></inline-formula> -band dual-mode RBWO packaged with permanent magnet experiments, a microwave pulse with the power of 3.9 GW, the frequency of 9.93 GHz, and the efficiency of 33% was measured when the diode voltage was 820 kV and diode current was 14.5 kA.

Thermal Model of the Output Traction Converter of an Electric Locomotive with Induction Motors

The aim of research is to develop a thermal model of the output converter of an electric locomotive with vector control, taking into account the operating modes of the electric locomotive. The aim was achieved by using energy losses at the moments of switching functions that describe the nature of the change in the curves of currents and power voltages of transistors and converter diodes. The object of research is an autonomous voltage converter, which is part of the traction drive of an electric locomotive with a vector control system. The simulation was carried out for an autonomous voltage converter, the load of which is two traction induction motors operating in the nominal mode. The temperature of transistors and diodes is obtained for the established modes of operation of traction motors. The most important results are the analytical dependence of thermal power losses in the inverter as a function of inverter phase currents and voltages. The significance of the results obtained is to establish the dependence of the temperature of the power devices of the inverter on the actual operating conditions of the electric locomotive. The established dependencies will further determine the spectral power of thermal noise. This will allow, when designing a traction drive control system, to develop an effective system for filtering thermal noise. This will increase the energy performance of the traction drive of the electric locomotive by improving the accuracy of regulation.

Transient Response of ESD Protection Devices for a High-Speed I/O Interface

System-efficient electrostatic discharge (ESD) design (SEED) models of a diode and transient voltage suppressor (TVS) were developed to study their transient response in a high-speed input/output interface. Previously reported SEED models were improved to strengthen their convergence stability and facilitate accurate predictions over a wide range of conditions. These improvements were required to accurately capture the race conditions between the TVS and <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> -chip diode, where the diode's turn <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> may prevent turn <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> of the TVS. Simulations and measurements were performed to demonstrate the impact of the ESD pulse's rise time on race conditions. During a race, results showed the worst-case quasi-static diode current could be twice as high for long rise-time pulses than for short rise-times where the TVS does not turn <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> , and <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> -chip diode current may be larger at low test voltages than at high test voltages where the TVS does turn <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> . Adding a small passive impedance between the external TVS and the <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> -chip diode helps the TVS turn <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> and reduce the current through the <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> -chip diode by more than 50%. Similarly, lengthening the trace between the TVS and diode could reduce <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> -chip diode current by up to a factor of two.

Experimental research on a novel C-band compact transit-time oscillator with low guiding magnetic field

Compactness and miniaturization are important development directions of high-power microwave sources at present. In the previous simulation research, we proposed a compact C-band transit-time oscillator with a low external guiding magnetic field. In order to verify whether the device can be better applied to practice, we have carried out experimental research on the device. With a diode voltage of 570 kV, current of 11.5 kA, and external guiding magnetic field of 0.35 T, the output microwave pulse of 1.3 GW is obtained at 4.3 GHz. The power conversion efficiency is about 20%. By observing the fluorescent screen imaging and the far-field pattern in the experiment, it can be seen that the working mode of the device is relatively stable. The experimental results show that the device has the ability to output GW-level C-band high-power microwave under a low external guiding magnetic field.

Radio Frequency Based Wireless Battery Charging of Cellular Phones

The challenge of regularly charging the battery of cellular phones has brought about new and more convenient ways to realising cellular battery charging. The wireless power platform has been explored for years bringing about many dimensions to its realisation. In this research, developed a wireless charging of Li-Ion battery of a cellular phone using commercial-off-the-shelf components vis-a-vis Radio Frequency (RF) energy. A MAX2623 voltage controlled oscillator was used to generate RF signals at a frequency of 915 MHz. Through a series of amplifier stages, the signal is radiated using a half-wave dipole antenna. The signal is received by a remote receiver module made up of 5 dBi gain half-wave dipole antenna which is impedance matched to a bridge rectifier made of SMS3929 Bridge Quad Schottky low turn-on voltage diodes. The rectified output is received by a EH4205 low voltage booster which amplifies the input into two paralleled MAX 682 charge pumps. The paralleled MAX 682 charge pump delivers a constant output voltage of 5 V DC and current of 500 mA. Within a 4 m radius the receiver module can receive enough power for the realisation of wireless battery charging.

120 GHz Frequency-Doubler Module Based on GaN Schottky Barrier Diode.

Traditional GaAs-based frequency multipliers still exhibit great challenges to meet the demand for solid-state high-power THz sources due to low breakdown voltage and heat dissipation of the Schottky barrier diode (SBD). In this study, a GaN SBD chain was fabricated with n−/n+-GaN structure. As a consequence, the breakdown voltage of 54.9 V at 1 μA and cut-off frequency of 587.5 GHz at zero bias were obtained. A 120 GHz frequency-doubler module based on the GaN SBD chain was designed and fabricated. When driven with 500 mW input power in a continuous wave, the output power of the frequency-doubler module was 15.1 mW at 120 GHz. Moreover, the experiments show that the frequency-doubler module can endure an input power of 2 W. In addition, it is worth noting that the SBD chain works well at an anode temperature of 337.2 °C.

Do Artificial Neural Networks Always Provide High Prediction Performance? An Experimental Study on the Insufficiency of Artificial Neural Networks in Capacitance Prediction of the 6H-SiC/MEH-PPV/Al Diode

In this paper, we study a new model that represents the symmetric connection between capacitance–voltage and Schottky diode. This model has a symmetrical shape towards the horizontal direction. In recent times, works conducted on artificial neural network structure, which is one of the greatest actual artificial intelligence apparatuses used in various fields, stated that artificial neural networks are apparatuses that proposal very high forecast performance by the side of conventional structures. In the current investigation, an artificial neural network structure has been generated to guess the capacitance voltage productions of the Schottky diode with organic polymer edge, contingent on the frequency with a symmetrical shape. Of the dataset, 130 were grouped for training, 28 for validation, and 28 for testing. In order to evaluate the effect of the number of neurons on the prediction accuracy, three different models with different neuron numbers have been developed. This study, in which an artificial neural network model, although well-trained, could not predict the output values correctly, is a first in the literature. With this aspect, the study can be considered as a pioneering study that brings a novelty to the literature.

A Single Source Switched-Capacitor Inverter with Boosting Capability

ABSTRACT Throughout this paper, a single-source hybrid switched-capacitor multilevel inverter is presented. The suggested topology is comprised of switched-capacitor modules. In this topology, two types of switched-capacitor modules are utilised: 1) basic module (BM) and 2) auxiliary units (AUs). By adding more AUs to the proposed topology, the voltage levels can be increased. By taking advantage of the switching procedure, three various configurations are made for the suggested MLI, in which the voltages of the capacitors are determined differently. Hence, in each configuration, according to the voltages of capacitors, different output voltage levels with different maximum output voltage and total standing voltage of switches are attained. To show the superiority of the proposed topology, a comprehensive comparison is made in terms of the number of DC voltage sources, power switches, capacitors, and diodes. Moreover, to investigate the performance of the suggested topology, a sample circuit with all configurations is simulated in MATLAB/Simulink. Finally, the experimental results are demonstrated to illustrate and verify the feasibility of the proposed inverter.