Showing papers on "Rise time published in 2019"

Properties of HPK UFSD after neutron irradiation up to 6e15 n/cm2

Abstract: In this paper we report results from a neutron irradiation campaign of Ultra-Fast Silicon Detectors (UFSD) with fluences of 1e14, 3e14, 6e14, 1e15, 3e15 and 6e15 neq/cm 2. The UFSD used in this study are circular 50 μ m thick Low-Gain Avalanche Detectors (LGAD), with a 1.0 mm diameter active area. Hamamatsu Photonics (HPK), Japan, produced the UFSD with pre-irradiation internal gain in the range 5–70 depending on the bias voltage. The sensors were tested pre-irradiation and post-irradiation with minimum ionizing particles (MIPs) from a 90Sr β -source. The leakage current, internal gain and the timing resolution were measured as a function of bias voltage at −20 °C and −30 °C. The timing resolution of each device under test was extracted from the time difference with a second calibrated UFSD in coincidence, using the constant fraction discriminator (CFD) method for both. The dependence of the gain upon the irradiation fluence is consistent with the acceptor removal mechanism; at −20 °C the highest gain decreases from 70 before radiation to 2 after a fluence of 6e15 n/cm2. Consequently, the timing resolution was found to deteriorate from 20 ps to 50 ps. The results indicate that the most accurate time resolution is obtained varying with fluence the CFD value used to determine the time of arrival, from 0.1 for pre-irradiated sensors to 0.6 at the highest fluence. Key changes to the pulse shape induced by irradiation, i.e. (i) the contribution of charge multiplication not limited to the gain layer zone, (ii) the shortening of the rise time and (iii) the reduced pulse height, were compared with the WF2 simulation program and were found to be in agreement.

Optimal PID tuning for controlling the temperature of electric furnace by genetic algorithm

Abstract: Temperature is one of the exigent parameters that needs to be controlled in today’s industries. Importantly this temperature control should be precise and fast. As the conventional controllers are not optimally tuned, the controller used for controlling the temperature of the electric furnace does not exhibit better performance. Its rise time and settling time is too large as well as it has a sizable amount of overshoot. This paper presents a Genetic Algorithm based PID controller to overcome the low precision, long rise time and settling time of the controller. In this algorithm, Integral of Absolute Error is taken as the object function for minimizing the error. Using this function, the algorithm engenders the optimum value of the gain parameters (Kp, Ki, Kd) for the PID controller. It shows better control over the conventional controllers. As the overshoot, settling time, and rise time are substantially improved, it provides sharp and prompt control over the temperature. This precise and instant control of temperature has a great impact on the food and medicine industries. As the temperature could be controlled precisely and instantly, we can avoid the change/degradation of the physical properties of the materials that are under process.

Optimized Charge Pump With Clock Booster for Reduced Rise Time or Silicon Area

Abstract: In this brief an improved Dickson charge pump (DCP) topology exploiting a clock boosting is presented. An accurate while simple theoretical model for the dynamic behavior of the charge pump is carried out. Analytical comparison with the traditional DCP reveals that the proposed solution can achieve a rise time or area reduction between 10% and 60% at the cost of a slight circuit complexity. Finally, simulation results using a 65-nm CMOS technology show the accuracy of the analytical model as well as the advantages of the proposed solution.

Electrical treeing in silicone gel under repetitive voltage impulses

Abstract: Silicone gel is widely used to encapsulate power electronic modules. The weakness of the electrical insulation is surface discharges initiated at the gel-substrate-electrode triple junction and the subsequent formation of cavities; so called electrical trees. The propagation characteristics of cavities under high frequency and fast rise time voltages, which are typical waveforms formed in power electronic modules, have not been fully understood. Thus, in this research, the influence of frequency, rise time, and polarity on electrical treeing under repetitive voltage impulses are investigated. The results show that discharge tracks under positive impulses have filamentary shapes, and discharge tracks under negative impulses have spindle-shapes. The cavity length increases with the frequency and is especially long when the rise time is short under high frequency. This indicates the importance of understanding the cavity propagation characteristics under actual voltage waveforms in power electronics modules.

Contribution to the analysis of PWM inverter parameters influence on the partial discharge inception voltage

Abstract: The work presented in this paper deals with the influence of pulse width modulation (PWM) power supply parameters on the partial discharge inception voltage (PDIV). For a given system supplied using PWM, the behavior of partial discharges may be different from a classical AC or DC power supply configuration. An experimental study was conducted in order to observe changes in PDIV levels with respect to PWM parameters such as duty cycle, switching frequency and voltage rise time. Measurements were done on a simple twisted pair of enameled wires, placed inside a climatic chamber for control of the environmental conditions. The experimental results show that the PDIV depends mainly on the waveform of the voltage oscillations; a voltage oscillation with a low frequency would favor the appearance of partial discharges (PD) because the probability of the presence of an initiatory electron to initiate the discharge is higher. Moreover, the waveform shape depends mainly on the rise time of the voltage and the length of the power cable. A parameter that also has a significant effect is the duty cycle; a low duty cycle in unipolar power is favorable for the appearance of PD.

Design and Development of an Inexpensive Sub-Nanosecond Gaussian Pulse Transmitter

Abstract: A design of a hybrid Gaussian pulse transmitter using a transistor-based pulse generator and two pulse-shaping networks, a shorted stub delay circuit and a 90° hybrid coupler, is presented. A transistor-based pulse generator drives the pulse-forming network to achieve a sub-nanosecond pulsewidth. The shorted stub delay line was modified to optimize the frequency response and phase linearity. The transistor-based pulse generator is an inexpensive way of producing a square pulse of sharp rise time; this design achieved 280-ps rise time. A Schottky diode was used to eliminate the negative part of the output pulse as well as to reduce the ringing. Multiple simulations and measurements were performed to study the circuit behavior. The measurement results demonstrated a pulsewidth as sharp as 153 ps with 0.83-V amplitude and a low ringing on the order of 10%. The Gaussian monopulse was obtained by feeding the Gaussian pulse to a broadband 90° hybrid, which acts as a differentiator in the time domain. The pulse has a width on the order of 100 ps. The transmitter circuit was completed by connecting the monopulse circuit with an antenna. The measured radiated pulse in the far field of the transmitter is a second derivative Gaussian pulse with 85 ps of pulsewidth.

A Fast Modular Semiconductor-Based Marx Generator for Driving Dynamic Loads

Abstract: The challenging demands of pulsed electron beam devices (such as the GESA device) with respect to their pulsed power supply have led to the development of a new semiconductor-based Marx generator. At a maximum output voltage of 120 kV and 600-A pulse current for a duration of up to 100 μS, stepwise arbitrary output waveforms are desired. A fast rise time of the generator is achieved by using fast switching circuitry, low inductance capacitors, and a low inductance stage arrangement. For low jitter triggering of all stages and efficient signal transmission, the generator uses an optical bus system for communication. Due to the inherent dynamic load characteristics of the GESA device, the generator features a fast overcurrent protection scheme. This paper presents selected design aspects of the generator and their validation in a small-scale assembly able of delivering up to 8 kV at 600-A load current.

Time response in carbon nanotube/Si based photodetectors

Abstract: We investigated the response of carbon nanotube/Si photodetectors to nanosecond light pulse using two electrode configurations for photovoltaic and photoconductive operations. When operating in photovoltaic mode, the devices show a linear dependence of the photocurrent as a function of the light pulse energy with rise time of 20 ns. In photoconductive mode, an increase of the maximum photocurrent as high as 30 times and a gain in the number of photogenerated charges up to 200% is recorded with a correspondent decrease in the time response below 10 ns. Current voltage characteristics measured as a function of the temperature indicate that the fast response of these devices can be ascribed to the formation of Schottky junctions at carbon nanotube/Si interface. These results make our devices comparable to most commercial photodetectors and pave the way for their use as avalanche photomultipliers.

Traveling-Wave Marx Circuit for Generating Repetitive Sub-Nanosecond Pulses

Abstract: The traveling-wave Marx generator was first proposed by Carl Baum to analyze the switch-closure propagation process in fast pulsed-power systems. To improve the performance of the transistorized sub-nanosecond pulse generator, the traveling-wave Marx circuit with inter-stage transmission lines is studied. Simulations indicate that the delay time and the impedance of inter-stage transmission lines [microstrip lines on printed circuit board (PCB)] are main factors affecting the pulse waveform. Based on it, the series connection of modularized Marx circuits is proposed, which has the advantages of adjustable amplitude and bendable circuit layout. A compact high-amplitude pulse generator is developed with the amplitude of 8.2 kV, the rise time of 150 ps, and the PCB length of 35 cm. For higher pulse repetition rate, the heat dissipation design of PCB is necessary; however, due to the variations in the microstrip line structure, the commonly used metallic heat sink may cause a significant decrease in pulse amplitude. Thus, a novel heat dissipation design is proposed by optimizing the layout of metallic sinks and introducing heat-conducting ceramic sinks. A high-repetition-rate pulse generator is developed with the maximum pulse repetition rate of 600 kHz, the amplitude of 1.1 kV, and the rise time of 160 ps.

High Speed and Wider Swing, Level Shifter Using Low-Temperature Poly-Silicon Oxide TFTs

Abstract: We report the CMOS level shifter (LS) made of p-type low-temperature poly-Si (LTPS) TFT using blue laser annealing (BLA) of amorphous Si (a-Si) and an n-type amorphous indium-gallium-zinc oxide (a-IGZO) TFT. Two cascaded inverters with the bootstrap capacitor are utilized. 1- clock signal and 2- supply voltage are employed to obtain a full output swing from high output voltage to ground. For an input swing of (2–10) V, the proposed LS shows a shifted output swing of (10–30) V. Having the fast rise time of 688 ns, it operates in the broad clock frequency range of 1 ~ 500 kHz. The operating clock frequency, ‘rail-to-rail’ level shifting and faster rise time confirm its superiority.

Detection and characterization of extreme wind speed ramps

Abstract: . The present study introduces a new method to characterize ramp-like wind speed fluctuations, including coherent gusts. This method combines two well-known methods: the continuous wavelet transform and the fitting of an analytical form based on the error function. The method provides estimation of ramp amplitude and rise time, and is herein used to statistically characterize ramp-like fluctuations at three different measurement sites. Together with the corresponding amplitude of wind direction change, the ramp amplitude and rise time variables are compared to the extreme coherent gust with direction change from the IEC wind turbine safety standard. From the comparison we find that the observed amplitudes of the estimated fluctuations do not exceed the one prescribed in the standard, but the rise time is generally much longer, on average around 200 s. The direction change does however exceed the one prescribed in the standard several times, but for those events the rise time is a minute or more. We also demonstrate a general pattern in the statistical behaviour of the characteristic ramp variables, noting their wind speed dependence, or lack thereof, at the different sites.

A comparison study of a novel self-contained electro-hydraulic cylinder versus a conventional valve-controlled actuator-part 1: Motion control

Abstract: This research paper presents the first part of a comparative analysis of a novel self-contained electro-hydraulic cylinder with passive load-holding capability against a state of the art, valve-controlled actuation system that is typically used in load-carrying applications. The study is carried out on a single-boom crane with focus on the control design and motion performance analysis. First, a model-based design approach is carried out to derive the control parameters for both actuation systems using experimentally validated models. The linear analysis shows that the new drive system has higher gain margin, allowing a considerably more aggressive closed-loop position controller. Several benefits were experimentally confirmed, such as faster rise time, 75% shorter settling time, 61% less overshoot, 66% better position tracking, and reduction of pressure oscillations. The proposed control algorithm is also proven to be robust against load variation providing essentially the same position accuracy. In conclusion, the novel self-contained system is experimentally proven to be a valid alternative to conventional hydraulics for applications where passive load-holding is required.

Improving the production of high-performance solar-blind β-Ga2O3 photodetectors by controlling the growth pressure

Abstract: In this work, β-Ga2O3 films are obtained by the RF magnetron sputtering method. Effects of the growth pressure on properties of the deposited β-Ga2O3 films and the corresponding solar-blind metal–semiconductor–metal photodetectors are investigated systematically. It is shown that when the deposition pressure increases, the full width at half maximum of β-Ga2O3 $$ \left( {\bar{2}01} \right) $$ X-ray diffraction peaks decreases firstly and then increase. The peak intensities increase firstly, reach a maximum at 25 mTorr and then decrease with increasing pressure. The similar variation tendency is also reflected on the bandgap, oxygen vacancy and roughness of β-Ga2O3 films. It is supposed that all these properties depend on two factors: atoms diffusion ability and the defects with growth pressure. By controlling the growth pressure, the fabricated interdigitated solar-blind photodetectors exhibit excellent characteristics, including a large spectral responsivity (303 A/W), a low dark current (10pA at 20 V), a large photo-to-dark current ratio (> 105), a high external quantum efficiency (over 1 × 105%) and a fast response speed (rise time: 0.52 s and fall time: 0.12 s).

Partial Discharge Behavior on Twisted Pair under Ultra-short Rise Time Square-wave Excitations

Abstract: The use of wide-bandgap (WBG) semiconductor device is increasing due to its capability to operate at much higher voltage, frequency and temperature compared with traditional semiconductor device. WBG semiconductor device is capable to generate voltages with ultra-high dv/dt (ultra-short rise time), which would alter the voltage stress in various electrical apparatus, e.g., inverter-controlled motors, and consequently change partial discharge (PD) behavior. Combine this with the fact that PD detection in inverter-controlled motor winding, even with slow-rising voltages, is intrinsically complicated, the study of PD behavior under ultra-fast squarewave voltages is much needed. In this paper, experimental observations and results for twisted pair samples stressed by an impulse generator with the ability of generating ultra-fast square-wave voltage are presented. Statements and hypotheses on PD behaviors and mechanism under ultra-fast dv/dt squarewave excitations are also put forward based on the test results.

Design of a prototype readout electronics with a few picosecond time resolution for MRPC detectors

Abstract: Multi-gap Resistive Plate Chamber (MRPC) is widely used as a Time-of-Flight (ToF) detector in physics experiments, featuring a high time precision requirement both on the detector and readout electronics. Efforts are being devoted to the research of a new MRPC structure, aiming at a much higher resolution, which demands an enhancement of the readout electronics performance. In this paper, a 10-ps prototype readout electronics for the MRPCs is presented. By using the cascaded high performance preamplifiers , gain between 20 dB and 40 dB is achieved for an 8-channel Analog Frontend Electronics (AFE) prototype module. The output signals of the AFE are digitized by a 16-channel high-speed Waveform Digitization Module (WDM), integrating the waveform correction and filtering, digital discrimination, linear interpolation, and other control logics within one Field Programmable Gate Array (FPGA) device. To evaluate the performance of the proposed design, a series of tests were conducted with synthesized signals from a pulse generator. These signals have the same rise time and width with that of real MPRC output signal, and cover the detector’s charge range. Test results indicate that the prototype readout electronics functions well, and its time resolution is better than 10 ps in the dynamic range of 50–500 fC.

Fiber-Optic Current Sensor Based on FBG and Optimized Magnetostrictive Composite

Abstract: In this letter, we present a compact, open-loop fiber-optic current sensor (FOCS) based on fiber Bragg gratings (FBG) and magnetostrictive composites of Terfenol-D (TD) optimized for enhanced sensitivity and linearity using small concentrations of this alloy. Using magnetic field concentration techniques and orientation of magnetic domains of the composites, a prototype of the proposed FOCS was built with different doping concentrations of TD (10%, 20%, and 40%) and characterized with currents of 15–700 Arms. The proposed FOCS showed a linear response for currents of up to 450 Arms with a linearity error of ±0.55%, a sensitivity of $201~\mu \text{V}$ /A, and 4.8 degrees of phase shift between output and input signals, which are competitive features compared to previous works, since it employs very small amounts of TD (1.5 g max.). The developed prototype also presented a fast response-time to a current transient and a rise time of 1.5 ms, allowing for the proposed FOCS to be applied not only for current sensing, but also to fault detection and monitoring in transmission and distribution lines.

Design, simulation and comparative analysis of a novel FinFET based astable multivibrator

Abstract: In this work, design and simulation of FinFET and CMOS based Astable Multivibrator (AMV) have been performed. Performance of proposed circuit was compared by varying resistance-capacitance ( R – C ) delay topology, supply voltage ( V dd ) and operating temperature (T) at 45 nm technology node using spice simulator. FinFET-AMV shows significant improvement over CMOS-AMV. An increase of 1.66% in amplitude, 84.4% in rise time and 73.3% in fall time of output square wave in FinFET-AMV was observed. A significant increase in the slew rate by 398% which improved the percentage wave slewed by 77.3% resulted in the increase of bandwidth by 655% from 768 MHz to 5.8 GHz. It was also observed that FinFET-AMV Starts to function properly at 0.39 V compared to CMOS-AMV which starts to function properly at 0.58 V. The power dissipation was found to be 2.23 times in FinFET-AMV, however, the study revealed that this could be improved by lowering the supply voltage.

Fast Pulsed Power Generation With a Solid-State Impedance-Matched Marx Generator: Concept, Design, and First Implementation

Abstract: In this article, we present the concept, design, and first implementation of a new solid-state pulse topology: the solid-state impedance-matched Marx generator (IMG). This new topology can bring fast, adjustable pulse generation to a wide range of pulsed power applications. Where the original IMG is a high-power device (using spark gaps) for relatively low-repetition-rate, high-energy-density physics, we require a pulse source with a (sub)nanosecond rise time at moderate voltages of tens of kilovolts at high repetition rates for transient plasma generation. To achieve this, we adapted the IMG pulse source concept to a solid-state concept with additional transmission lines and metal–oxide–semiconductor field-effect transistor (MOSFET) switches. In this article, we present the general concept, a 20-stage design (with 3-D transient electromagnetic simulations), and a first 5-stage, 5-kV prototype. The prototype achieves 5–6-ns rise time pulses at voltages up to 2.5 kV into a matched 50- $\Omega $ load (due to an oscillation in the drive circuit, the pulse was somewhat distorted at higher voltages) and can generate flexible pulse waveforms. Finally, improvements are suggested to achieve the desired pulse specifications.

Electrical treeing initiation and breakdown phenomenon in polypropylene under DC and pulse combined voltages

Abstract: In this paper, the effects of DC voltage, pulse voltage and pulse frequency on the electrical treeing characteristics in polypropylene (PP) under DC and pulse combined voltages were investigated. The rise time of the pulse voltage is 50 μs. The DC amplitude range is from −25 kV to +25 kV, and the pulse amplitude range is from −35 kV to +35 kV. The pulse frequency range is from 400 to 800 Hz. The results show that the electrical tree structures change with different DC amplitudes, pulse amplitudes and pulse frequencies. With the increase in the positive DC voltage, the treeing process is accelerated. However, with the increase in the negative DC amplitude, the breakdown time decreases first and then increases. This phenomenon is attributed to the different charge transport processes under different DC amplitudes. With the pulse amplitude and frequency increasing, the growth rate and accumulated damage increase significantly. The pulse amplitude and frequency affect significantly the breakdown time. The pulse voltage with the same polarity as that of the DC voltage is more likely to cause breakdown than the pulse voltage with opposite polarity of that of the DC voltage because of the larger effective values of the composite voltages.

Nanosecond pulse generator based on cascaded avalanche transistors and Marx circuits

Abstract: Avalanche transistors have been widely used in nanosecond pulse generators because of high switching speed, low jitter, small size, low intrinsic inductance, and high-frequency operation. Marx circuits based on cascaded switches are often used to increase the voltage amplitude. In this paper, some current-limiting resistors in traditional Marx circuits were replaced by diodes to speed up the charging speed, to reduce the energy loss, and to increase the repetitive frequency. The influence of capacitance and the current limiting resistor on the output voltage amplitude and frequency were analyzed. The minimum on-resistance of a single BJT was calculated to be about 2.5 Ω, and the equivalent internal resistance of the Marx circuit based on cascaded switches reduced the output voltage amplitude over the load, so multiple Marx circuits in parallel were used to increase the output voltage amplitude. By changing the number of Marx modules in parallel, the influence of the equivalent internal resistance of the circuit on the output pulse was studied. By changing the load resistance, it verified that the Marx circuit in parallel had a better boosting effect over low-resistance loads. The experiments show that nanosecond pulses with a rise time of 3.4 ns, an amplitude of 2.5 kV and a repetitive frequency of 15 kHz were obtained over a 50 Ω resistor load with four Marx circuits in parallel.

Performance-enhanced silicon thermo-optic Mach-Zehnder switch using laterally supported suspended phase arms and efficient electrodes.

Abstract: We report a silicon thermo-optic Mach-Zehnder switch with a broadband, low switching power, and fast response. A broadband 3 dB directional coupler is used to act as a power splitter. Laterally supported suspended phase arms are employed to substantially reduce the switching power without sacrificing too much on the temporal response. Furthermore, two metallization steps are utilized to further decrease the power consumption. We experimentally obtain a switching power as low as 1.1 mW, as well as a fast response of 76 and 48 μs for rise time and fall time, respectively. The demonstrated device also has a relatively high mechanical strength and compact size, making it promising to be applied in silicon photonic integrated circuits.

Multistage converter of high-voltage subnanosecond pulses based on nonlinear transmission lines

Abstract: This paper presents new experimental data that enable the observed processes in nonlinear ferrite lines to be related with the theoretical positions of the spin waves of the magnetization precession under the conditions of a high-power microwave. Such an approach has not been considered in earlier discussions on the subject and can contribute to the theory of the generation of oscillations in a gyromagnetic ferrite medium. These new aspects were used to design a new type of generator. The specific feature is the presence of regularity in the ferrite lines in the generation mode of microwave oscillations. The repeating regularity enabled the implementation of multistage pulse shape converters capable of operating in two modes and providing extreme parameters of the output pulses. Two variants of multistage converters of nanosecond high-voltage pulse shapes with a duration of ∼4 ns at a half-height and with an amplitude of −500 kV were designed and tested. The assembly of the converters and the driving generator are described in the stationary setup. In the first case, the rise time shortened to ∼45 ps, and the amplitude increased to −850 kV due to the sharpening of a pulse and the formation of a shock wave by the cascade of three nonlinear transmission lines. A record rate for the increase of the leading peak voltage of ∼15.5 MV/ns was reached. In the second case, the new approach for the generation of a sequence of subnanosecond pulses was presented and tested, and each pulse of the previous stage was modulated by the next stage doubling the number of pulses while conserving a deeper modulation. As a result, at the top of the incident pulse, a sequence of subnanosecond peaks with a large modulation depth (∼70%) was formed when the maximum voltage amplitude reached −700 kV. The results of the emission of such pulses are also presented.

Effect of rise time on nanosecond pulsed surface dielectric barrier discharge actuator

Abstract: Nanosecond pulsed surface dielectric barrier discharge (ns-SDBD) actuator is a novel technology for active flow control due to its high control capability and low power consumption. The electrical, and aerodynamic, characteristics of ns-SDBD actuator with different rise times are investigated by electrical measurement system, Schlieren optical system, and particle image velocimetry (PIV) system. Experimental results show that the short rise time leads to a high current amplitude and a diffuse-like plasma layer. The deposited energy reaches its maximum (9.26 mJ) at a rise time of 50 ns, and then declines, finally, slight changes occur when the rise time is increased from 150 ns to 500 ns. Furthermore, a circular arc wave and a plane wave are produced due to the localized heating. The intensity of the circular arc wave increases when the rise time decreases and the propagation distance of induced pressure waves in the vertical direction increases in a quasi-linear manner. In addition, due to the greater ability to transmit output energy to the surroundings, and the stronger tangential acceleration ability in the case of a short rise time, the area of action for the starting vortex is larger when rise time decreases and two vortexes are formed, which is conducive to mixing with the airflow and improving flow control capability.

555-Timer and Comparators Operational at 500 °C

Abstract: This paper reports an industry standard monolithic 555-timer circuit designed and fabricated in the in-house silicon carbide (SiC) low-voltage bipolar technology. This paper demonstrates the 555-timer integrated circuits (ICs) characterization in both astable and monostable modes of operation, with a supply voltage of 15 V over the wide temperature range of 25 °C–500 °C. Nonmonotonic temperature dependence was observed for the 555-timer IC frequency, rise time, fall-time, and power dissipation.

Survey on Single Stage Amplifiers for Column Drivers in Active Matrix LCD Panels Leading to a Highly Linear Rail-to-Rail Robust Amplifier

Abstract: This paper reviews single stage amplifiers identified in the literature as well as presents a new structure single stage highly linear rail-to-rail amplifier intended for column drivers in Active Matrix Liquid Crystal Display (AMLCD). The new proposed amplifier is based on applying current splitting technique on a rail-to-rail differential pair thus elevating the overall performance of the amplifier in terms of different performance parameters such as effective transconductance, output resistance, DC gain and unity gain frequency among others. One major advantage of the new proposed amplifier is its capability of providing a rail-to-rail stable operation without the need for compensation. The performance of the new proposed amplifier is tested on LTspice using 90nm CMOS technology under 1 Volts supply voltage and compared to other existing single stage amplifiers. Simulation results shows that the proposed amplifier provides a high DC gain, high effective transconductance and high output resistance while maintaining a stable operation with a phase margin of 80°. Obtained results also confirms that the amplifier exhibits rail-to-rail operation while maintaining a very low Total Harmonic Distortion (THD). The pulse response of the proposed amplifier indicates a fast response with a rise time and fall times almost twice as fast as the other examined topologies. Against Process, Voltage and Temperature (PVT) variations, the amplifier exhibits a robust performance as the DC gain variation range was within 20% only which is much less than the other examined topologies.

Fast Response Solar-Blind Photodetector with a Quasi-Zener Tunneling Effect Based on Amorphous In-Doped Ga2O3 Thin Films

Abstract: A high-performance solar-blind photodetector with a metal-semiconductor-metal structure was fabricated based on amorphous In-doped Ga2O3 thin films prepared at room temperature by radio frequency magnetron sputtering. The photodetector shows a high responsivity (18.06 A/W) at 235 nm with a fast rise time (4.9 μs) and a rapid decay time (230 μs). The detection range was broadened compared with an individual Ga2O3 photodetector because of In doping. In addition, the uneven In distribution at different areas in the film results in different resistances, which causes a quasi-Zener tunneling internal gain mechanism. The quasi-Zener tunneling internal gain mechanism has a positive impact on the fast response speed and high responsivity.

Partial Discharge Detection Strategies under Fast Rise Time Voltages Generated by Wide-bandgap Semiconductor Devices

Abstract: Wide-bandgap (WBG) semiconductor device is one of the leading contenders for the next generation semiconductor device. Its advantages include but not limited to: higher voltage rating, switching speed and frequency. However, when electrical applications are driven by WBG devices, the voltage stress is inevitably changed. To be more precise, the voltage stress is more likely to be enhanced based on the premature failures observed for various applications driven by WBG devices. As has been well accepted, partial discharge (PD) is considered as the main cause for insulation failure in high frequency equipment. Thus, it is necessary to study PD behaviors under the new stress introduced by WBG device. However, the issue is inherently challenging due to the nature of the equipment under test and the extremely high dv/dt (fast rise time) square-wave voltage introduced. Huge charging/discharging current would be seen at the rising/falling edges of the square-wave pulse train. The magnitude of the charging/discharging current can be hundreds of or even thousands of times larger than that of PD pulse current. In some cases, even in frequency domain, the PD pulse current would be masked by the charging/discharging current. In this paper, a summary is made on past research related to PD detection strategies under fast rise time square-wave voltage or impulse voltage. Their advantages and disadvantages would be introduced to provide a full picture about this issue for future researchers when the need of PD detection under fast rise time excitations arises.

A Novel Filter Extracted Equivalent Control Based Fixed Frequency Sliding Mode Approach for Power Electronic Converters

Abstract: The key issue in the implementation of the Sliding Mode Control (SMC) in analogue circuits and power electronic converters is its variable switching frequency. The drifting frequency causes electromagnetic compatibility issues and also adversely affect the efficiency of the converter, because the proper size of the inductor and the capacitor depends upon the switching frequency. Pulse Width Modulation based SMC (PWM-SMC) offers the solution, however, it uses either boundary layer approach or employs pulse width modulation of the ideal equivalent control signal. The first technique compromises the performance within the boundary layer, while the latter may not possess properties like robustness and order reduction due to the absence of the discontinuous function. In this research, a novel approach to fix the switching frequency in SMC is proposed, that employs a low pass filter to extract the equivalent control from the discontinuous function, such that the performance and robustness remains intact. To benchmark the experimental observations, a comparison with existing double integral type PWM-SMC is also presented. The results confirm that an improvement of 20% in the rise time and 25.3% in the settling time is obtained. The voltage sag during step change in load is reduced to 42.86%, indicating the increase in the robustness. The experiments prove the hypothesis that a discontinuous function based fixed frequency SMC performs better in terms of disturbances rejection as compared to its counterpart based solely on ideal equivalent control.

Solid-State High-Voltage Pulse Generator for Low Temperature Plasma Ion Mobility Spectrometry

Abstract: Low-temperature plasma ion mobility spectrometry (LTP-IMS) is the method to identify some materials by measuring concentration of gas phase ions. IMS used in a wide range of laboratory-based biomedical research studies. A nanosecond pulse generator is necessary for LTP-IMS apparatus to enable direct analysis of various chemical compounds without having to evaporate the analyte or seek a solvent or any reagent. In this paper, a dual Marx pulsed generator for LTP-IMS Ionization power supply is proposed based on a new combination of some solid-state switches including insulated gate bipolar transistor (IGBT) and avalanche bipolar junction transistors (BJTs). The compact dual Marx generator is composed of a series of avalanche BJTs and an IGBT as the trigger switch, where its rise time is reduced from 100 to 5 ns by using an avalanche BJT in its command circuit. In this way, a controllable high-voltage pulse generator has designed, built, and tested. The proposed circuit can be used to generate the repetitive high-voltage pulses necessary for low temperature ionization in advanced IMS apparatus. The output voltage has an amplitude of up to 6 kV with pulse widths in the range of 40–1000 ns and pulse repetition rates up to 2 kHz, having rise time and fall time less than 10 ns independent of the load specifications.