High-voltage Amplifier Research Articles

WITHDRAWN: An 81MV/s SR, ±12.5V Swing Operational Amplifier with 2.15nV/√Hz Noise floor

—This brief introduces a high-voltage, high-speed and low-noise operational amplifier designed with a standard BCD process. High noise performance is achieved by using the bipolar transistors as input stage. However, the significant parasitic capacitance of the bipolar transistors leads to slew rate (SR) deterioration bandwidth deterioration. To overcome these problems, an improved folded-cascode structure with bipolar-based source degeneration current mirror (BSD-CM), the mirror pole control technique and the fast response output stage is proposed. The simulation results show that the BSD-CM improves the bandwidth by 35dB compared to the traditional bipolar current mirror. The mirror pole control improves the bandwidth of amplifier by 9dB. The fast response output stage improves the SR by 2 times. The proposed amplifier is fabricated with a standard 0.18 μm BCD process. The chip area is 3.75 mm2. The measurement results show that this amplifier consumes 4.5 mA with a ±15 V voltage supply. The SR is 81MV/s, the GBW is 158MHz and the input referred noise is 2.15 nV/√Hz.

Elastic wave based Non-Destructive Evaluation for joint characterization in thin section welded structures

Ensuring safety and reliability in aerospace, automotive, civil, and mechanical industries require efficient evaluation of weld integrity. This involves assessing mechanical, metallurgical, and morphological properties of the bonded zone. Elastic wave-based Non-Destructive Evaluation provides a cost-effective and efficient alternative for long-range, through-thickness, and in-situ inspection. For this investigation, two 2mm-thick plates of Al5052-Al6083, measuring 250mm x 180mm, were friction stir welded in a lap arrangement. Out-of-plane displacement was generated by a Piezoelectric Transducer and measured using a Laser Doppler Vibrometer. To generate pulses of 60V and 120V at frequencies of 60kHz and 80kHz, a high-voltage amplifier was utilized. Additionally, visco-elastic bands were employed at the structure boundary for damping purposes. This study used both fundamental modes to analyze various weld discontinuities such as voids, tunnels, microcracks, hooking bonds etc. Frequency-wavelength filtering techniques were applied for advanced signal processing. Also, the results were cross validated using X-ray, SEM, EDS, and CT scans. This investigation found a direct correlation between lamb wave propagation and weld performance, as the defect size increased, wave transmission decreased from 13.50dB to 6.34dB at 120V and 60kHz. Abruptly lower transmission behavior at 80 kHz of D2 defect is due to S0 mode conversion. Keywords: Lamb wave, Non-Destructive Evaluation, Weld integrity, Friction stir welding, Thin section lap joint

Lamb wave based damage imaging under nonlinear chirp excitation

Considering a trade-off between temporal-spatial resolution and multi-mode nature of Lamb waves, tone bursts with short durations are usually used as excitations in Lamb wave based damage detection. A short-duration excitation usually requires a large amplitude to carry sufficient energy so as to obtain response signals with enough signal-to-noise ratio and cover a large inspection area. In this paper, an alternative Lamb wave damage imaging method using nonlinear chirp (nonlinear frequency modulation, NLFM) excitation with a long duration and a small amplitude is proposed. The signal processing techniques of pulse compression and dispersion compensation are adopted to compress the long-duration wave packets of response signals into short ones. Compared with conventional tone burst excitations with short durations and small amplitudes, due to the long duration of the nonlinear chirp excitation and the use of pulse compression, sufficient energy can be applied to transducers under small amplitude excitations so the image contrast in imaging will not degrade. Furthermore, as large amplitude excitations are no longer required, high voltage amplifiers are not necessary so the hardware of the Lamb wave testing system is simplified. Experiments on a carbon steel plate with an artificial crack are carried out and Lamb wave signals are collected using a linear array consisting of nine PZTs. Experimental results under the NLFM signal and conventional tone bursts are provided. Experimental results show that under the condition of the same excitation amplitude, the proposed method under the NLFM excitation can achieve better imaging quality compared with methods under conventional tone bursts.

Customization of an atomic force microscope for multidimensional measurements under environmental conditions.

Atomic force microscopy (AFM) is an analytical surface characterization tool that reveals the surface topography at a nanometer length scale while probing local chemical, mechanical, and even electronic sample properties. Both contact (performed with a constant deflection of the cantilever probe) and dynamic operation modes (enabled by demodulation of the oscillation signal under tip-sample interaction) can be employed to conduct AFM-based measurements. Although surface topography is accessible regardless of the operation mode, the resolution and the availability of the quantified surface properties depend on the mode of operation. However, advanced imaging techniques, such as frequency modulation, to achieve high resolution, quantitative surface properties are not implemented in many commercial systems. Here, we show the step-by-step customization of an atomic force microscope. The original system was capable of surface topography and basic force spectroscopy measurements while employing environmental control, such as temperature variation of the sample/tip, etc. We upgraded this original setup with additional hardware (e.g., a lock-in amplifier with phase-locked loop capacity, a high-voltage amplifier, and a new controller) and software integration while utilizing its environmental control features. We show the capabilities of the customized system with frequency modulation-based topography experiments and automated voltage and/or distance spectroscopy, time-resolved AFM, and two-dimensional force spectroscopy measurements under ambient conditions. We also illustrate the enhanced stability of the setup with active topography and frequency drift corrections. We believe that our methodology can be useful for the customization and automation of other scanning probe systems.

Electrostatic separation process of metal/plastic granular mixtures using a horizontal rotating disk

A rotating disk electrostatic separation device was developed and studied for the separation of mm-size metal and plastic particles. The device is constituted by two helical concentric electrodes build up on the top side of a simple layer PCB, and supplied by two high voltage amplifiers delivering square, DC and AC waveform signals. The separation mechanism is based on an electro-adhesion force applied on metal particles and an air suction force for recovering the plastic particles. The obtained results as functions of the voltage level, the rotating speed, and the suction force confirmed the high separation performance in terms of recovery and purity rates which reached values of 95 and 100%, respectively.

A Portable Real-Time Test Bench for Dielectric Elastomer Actuators

Recently, a significant amount of research has been devoted to soft robots. Artificial muscles belong to the most important components of soft robots. Dielectric elastomer actuators (DEAs) represent the technology that comes closest to the capabilities of a natural muscle, making them the best candidates for artificial muscles in robotics and prosthetics applications. To develop these applications, an analysis of DEAs in a test bench must be possible. It is important that the environmental conditions are known, and all components are specified, which is not the case in most publications. This paper focuses on the development of a real-time test bench for DEAs which provides environmental conditions and all components that are specified. Its goal is to open up the research field of dielectric elastomer actuators or soft robots. The stacked DEA used is powered by a high-voltage amplifier, which can be controlled via a real-time block diagram environment together with a data acquisition (DAQ) device. The response of the actuator is measured with a laser triangulation sensor. Furthermore, information about the applied voltage, the operating current, the temperature, and the humidity are collected. It was demonstrated that the selected laser sensor is a suitable device for this application. Moreover, it was shown that the selected high-voltage amplifier is adequate to power a DEA. However, the DAQ is not fast enough to measure the actuator current. It was demonstrated that housing keeps environmental conditions constant, is transportable, and offers the flexibility to investigate different DEAs.

Comprehensive Controller for Super Sonic Molecular Beam Gas Chromatograph Mass Spectrometer

This paper presents a new, comprehensive digital circuit used for the control of a novel gas chromatograph mass spectrometer (GC-MS) interface that is based on supersonic molecular beam (SMB). The circuit includes a Texas Instruments 150 MHz digital signal controller (DSC), high voltage amplifiers for 8 independent channels and 4 independent channels of high resolution pulse width modulation (PWM). The circuit, along with a sophisticated embedded program and a custom made personal computer (PC) application, control all aspects of the interface: smart filament emission-current stabilization, static and scanning mass-dependent ion-source voltages, transfer-line heater proportional integral differential (PID) controls with thermocouple feedbacks, on/off valves, relays and several peripheral device controls that enable the full operation of a turbo-molecular vacuum pump, and of gas flow and pressure controllers. All aspects of this comprehensive controller were successfully tested. The signal for the 450 Th ion (C32H66) for example increased by 123% which is a significant increase. It is obvious that correctly tuned dynamic voltages can guarantee the optimal signal for each mass.

A Self-Powered Dielectrophoretic Microparticle Manipulation Platform Based on a Triboelectric Nanogenerator.

Lab-on-a-chip systems aim to integrate laboratory operations on a miniaturized device with broad application prospects in the field of point-of-care testing. However, bulky peripheral power resources, such as high-voltage supplies, function generators, and amplifiers, hamper the commercialization of the system. In this work, a portable, self-powered microparticle manipulation platform based on triboelectrically driven dielectrophoresis (DEP) is reported. A rotary freestanding triboelectric nanogenerator (RF-TENG) and rectifier/filter circuit supply a high-voltage direct-current signal to form a non-uniform electric field within the microchannel, realizing controllable actuation of the microparticles through DEP. The operating mechanism of this platform and the control performance of the moving particles are systematically studied and analyzed. Randomly distributed particles converge in a row after passing through the serpentine channel and various particles are separated owing to the different DEP forces. Ultimately, the high-efficiency separation of live and dead yeast cells is achieved using this platform. RF-TENG as the power source for lab-on-a-chip exhibits better safety and portability than traditional high-voltage power sources. This study presents a promising solution for the commercialization of lab-on-a-chip.

High-voltage detuning power system of HIRFL-CSRm electron cooler for Dielectronic-Recombination experiments

Dielectronic-Recombination (DR) experiments of highly charged ions are performed in the main Cooler Storage Ring (CSRm) at Heavy Ion Research Facility in Lanzhou (HIRFL) accelerator complex. A new detuning power system of the electron cooler is developed to modulate the electron velocity from the cooling velocity and thus control the collision energy in the experiment. In this paper, the design and commissioning of the detuning power system are reported. The detuning power supply adopts the scheme of HVDC (high-voltage DC) and HVA (high-voltage amplifier) connected in series. A FPGA digital controller combined with a high-precision ADC/DAC board is used for multiple-linear voltage settings and feedback. The output maximum DC voltage is −5 kV and the detuning voltage is in the range of 0 to ±1 kV. The main features are the good output voltage stability of 10 ppm and the rapid voltage changing of 10 V/μs. The decoupling and protection of the detuning power supply under the high detuning pulse current are described as well. Finally, a DR spectrum of Ar15+ ions measured with the new detuning power system is presented. The experimental result shows a good resolution, verifying the reliability and feasibility of the design.

The DC Performance and RF Characteristics of GaN-Based HEMTs Improvement Using Graded AlGaN Back Barrier and Fe/C Co-Doped Buffer

In this article, the impact of the graded AlGaN back barrier and Fe\C co-doping buffer structure on the AlGaN <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$/$ </tex-math></inline-formula> GaN high electron mobility transistors (HEMTs) is proposed and systematically investigated. Due to effective suppression of Fe tail in unintentionally doped GaN (uid-GaN) layer by the insertion of the thick graded AlGaN back barrier layer, a large maximum drain current density and a transconductance peak are achieved. Meanwhile, the breakdown voltage is significantly improved by the use of Fe\C co-doping GaN buffer design. More importantly, it is revealed that the graded-AlGaN design can reduce the range and intensity of the electrical potential distribution in uid-GaN layer and then effectively suppress the acceptor-induced trapping\detrapping effect under high drain voltage. The RF small-signal performance of Fe-doped GaN (GaN:Fe)\C co-doping buffer HEMT exhibits significant improvement. In addition, load-pull measurement at 8 GHz revealed that a saturation power increases from 38.04 to 41.07 dB, a power gain increases from 9.06 to 10.58 dB, and an associate power-added-efficiency (PAE) increased from 40.27% to 50.18%. Our proposed GaN-based epitaxial structure can not only suppress the gate lag by reduce AlGaN surface electric field, but it can also suppress the drain lag by reduce the amplitude and range of potential distribution. It indicates that our proposed device has great potential for future high-voltage RF power amplifier application.

The Usage of High Voltage Amplifiers to Set up Reference Calibrators for Combined and Impulse Voltages up to 1 kV

An approach to set up reference calibrators to generate combined voltages, using voltage amplifiers, has been demonstrated. Four high voltage amplifiers were tested and studied. Measurements and experiments have shown that this approach could be used to set up calibrators for combined voltages, at least up to 1 kV. The advantage is the flexibility to generate separate or combined wave shapes (combination of AC, DC, distorted shapes, double exponential impulses such as lightening and switching impulses). This method could be beneficial to the fields where impulses, combined or not with DC or AC voltages, need a reference calibrator to calibrate digitizers. This method, relatively cheaper and simple to develop, reaches high metrological performance. For example, for lightning impulses up to 900 V, the uncertainties are lower than 0.2 % for the peak voltage, 1 % for the front time and 0.5 % for the time to half value . The traceability to the international system of units can be ensured by characterizing the gain using a step response, followed by the convolution technique.

A novel microscale platform for leukemia tumor treating field therapy and electrochemical screening

Currently, chemotherapy methods are among the most commonly used strategies for all cancer treatments, including leukemia. Despite the marked successes of such therapies, their inevitable side-effects and dose-limiting complications hinder reaching the maximum efficacy. Recently, Tumor Treating Fields (TTFields) that exploits low intensity and intermediate frequency electric fields has shown great promise as a noninvasive cancer therapy. Combining TTFields and conventional chemotherapies allows treatment with lower drug doses, resulting in significant clinical outcomes and fewer side effects. Although such combinational therapies have been used to treat a wide range of cancer types, their potential applications on leukemia have yet to be explored. This study investigates the effects of TTFields on the leukemia cells in combination with imatinib using a novel microelectrode array platform enabling the on-chip application of TTFields. Microfabrication allows applying TTFields by conventional signal generators with a maximum 20 V peak-to-peak external voltage eliminating commonly used high voltage amplifiers. We evaluated the effectiveness of our method with several biological assays, including flow cytometry, Annexin-V staining, and MTT. Our results indicate that combining TTFields and imatinib can halve the required drug dose (1 μM to 0.5 μM) to reach the apoptotic rate (68.55%±2.4%) obtained by imatinib alone. By comparing the cells numbers, after 72 h, the K562 cells number in our combinational treatment were 7% lower than the initial values seeded, suggesting a considerable net reduction in the tumor cell. Furthermore, to explore the underlying mechanism, an electrochemical approach is employed to measure the secreting contents of the leukemia cells after treatment. We concluded that the enhancement in treatment efficacy could be attributed to the induction of intracellular reactive oxygen species by TTFields, resulting in increased cell apoptosis. Our method provides an in vitro basis to assess the application of TTFields in combination with chemotherapy for leukemia cells.

A time-shared switching scheme designed for multi-probe scanning tunneling microscope.

We report the designof a time-shared switching scheme, aiming to realize the manipulation and working modes (imaging mode and transport measurement mode) switching between multiple scanning tunneling microscope (STM) probes one by one with a shared STM control system (STM CS) and an electrical transport characterization system. This scheme comprises three types of switch units, switchable preamplifiers (SWPAs), high voltage amplifiers, and a main control unit. Together with the home-made software kit providing the graphical user interface, this scheme achieves a seamless switching process between different STM probes. Compared with the conventional scheme using multiple independent STM CSs, this scheme possesses more compatibility, flexibility, and expansibility for lower cost. The overall architecture and technique issues are discussed in detail. The performances of the system are demonstrated, including the millimeter scale moving range and atomic scale resolution of a single STM probe, safely approached multiple STM probes beyond the resolution of the optical microscope (1.1 µm), qualified STM imaging, and accurate electrical transport characterization. The combinational technique of imaging and transport characterization is also shown, which is supported by SWPA switches with ultra-high open circuit resistance (909TΩ). These successful experiments prove the effectiveness and the usefulness of the scheme. In addition, the scheme can be easily upgraded with more different functions and numbers of probe arrays, thus opening a new way to build an extremely integrated and high throughput characterization platform.

Development of a compact power supply for dielectrophoretic applications

ABSTRACT Conventional supply systems of electrical curtains for dielectrophoretic applications generally use as many frequency generators in combination with as many linear high-voltage amplifiers. This paper aims to develop an ‘all-in-one’ compact power supply instead of the conventional supply system. The developed three-phase power supply delivers a voltage up to 1000 V with a variable frequency. The power supply includes a 1 kV DC/HVDC converter, which is then converted into three rectangular shape voltages with a phase shift of 120°. The developed supply was successfully tested and compared with the conventional supply system for the displacement of micronised plastic particles.

Designing and setting up the scintillationdetector using CsI(Tl) crystals and avalanche photodiode for gamma-ray measurement

Localization of the scintillation detectors manufacturing process has many benefits because of the high detection efficiency of the detectors, user-friendly, and consistent with general research objectives. Using a photodiode instead of a photomultiplier tube (PMT) allows saving energy, shortening the detector volume, and removing high voltage power supply and amplifier. The combination of CsI(Tl) scintillator, avalanche photodiode, charge sensitive preamplifier, wide range amplifier, and power supply system has been integrated into the detector. This study presents new results in manufacturing a home-made scintillation detector using avalanche photodiode. The detectors of this type can be used in hospitals, in the nuclear laboratory of universities for the students training, etc.

High-efficiency high-voltage class F amplifier for high-frequency wireless ultrasound systems.

This paper presents a novel amplifier that satisfies both low distortion and high efficiency for high-frequency wireless ultrasound systems with limited battery life and size. While increasing the amplifier efficiency helps to address the problems for wireless ultrasound systems, it can cause signal distortion owing to harmonic components. Therefore, a new type of class F amplifier is designed to achieve high efficiency and low distortion. In the amplifier, the resonant circuit at each stage controls the harmonic components to reduce distortion and improve efficiency. Transformers with a large shunt resistor are also helpful to reduce the remaining noise in the input signal. The proposed class F amplifier is tested using simulations, and the voltage and current waveforms are analyzed to achieve correct operation with adequate efficiency and distortion. The measured performance of the class F amplifier has a gain of 23.2 dB and a power added efficiency (PAE) of 88.9% at 25 MHz. The measured DC current is 121 mA with a variance of less than 1% when the PA is operating. We measured the received echo signal through the pulse-echo response using a 25-MHz transducer owing to the compatibility of the designed class F amplifier with high- frequency transducers. The measured total harmonic distortion (THD) of the echo signal was obtained as 4.5% with a slightly low ring-down. The results show that the low THD and high PAE of the new high-efficiency and high-voltage amplifier may increase battery life and reduce the cooling fan size, thus providing a suitable environment for high-frequency wireless ultrasound systems.

The Application of Classical Control in the Design and Analysis of Power Amplifiers for Driving Piezoelectric Stack Actuators

This study proposes a new method to design an analog circuit based on the control model of the circuit, and the method is applied in the design of the power amplifiers for driving piezoelectric stack actuators. Focusing on the stability of the circuit, two power amplifiers for driving piezoelectric stack actuators are analyzed deeply. The power amplifier using high-voltage operational amplifiers has a simple circuit structure, and the bandwidth and the ripple of the power amplifier are about 43 kHz and 16 mV, respectively. As for the power amplifier using general operational amplifiers, it possesses the qualities of low cost and simple circuit structure, and the bandwidth and the ripple are 53 kHz and less than 2 mV, respectively. Moreover, the proposed power amplifiers can well drive the mechanism stage during the moving range of the piezoelectric stack actuator, and the travelling ranges are both about 13 μm. Viewing the circuit design as control system design, applying control system design method in circuit design and working with PSpice simulation of the circuit: these are the main contents of the proposed method, and the method offers an answer to designing a power amplifier systematically.

A compact high frequency voltage amplifier for superconductor–semiconductor logic interface

The many advantages of cryogenically cooled single-flux quantum (SFQ) circuits imply that the high speed and low voltage output signals must be amplified and interfaced with standard electronics. State-of-the-art low-noise and wide-band amplifiers are required to interface with room temperature electronics. One solution is to place preamplifiers at the cryogenic stage, which requires specific semiconductor design and fabrication. However, a more viable and energy-efficient approach is to integrate the pulsed logic circuit output stages with on-chip superconductor preamplifiers. We designed, fabricated, and tested an on-chip compact voltage multiplier integrated with the output stage of SFQ circuits to increase the voltage amplitude of SFQ pulses. The circuit is designed with the same technology as the logic circuit hence its noise level is lower, and it works at higher frequencies compared to complementary metal-oxide semi-conductor amplifiers and due to quantized nature of it there is no added noise. The fabricated circuit has a compact size of 160 µm × 320 µm and provides about 10 dB gain with measured 600 µV output voltage at frequencies up to ∼25 GHz in simulations. By stacking more levels, over 20 dB gain at circuit level is achievable as shown in simulations. Moreover the gain of the superconductor voltage amplifier is quantized and programmable.

A driving power with filter compensator for micro-positioning improvement of piezoelectric bimorph actuators

To improve the micro-positioning accuracy of piezoelectric bimorph actuators, a driving power was designed with filter compensator. Amplifier modular was designed with high-voltage operational amplifier, and filter compensator modular is responsible for charge signal. Simulation results show that the output of filter compensator modular is proportional to the electric charge on the actuator. Experimental results indicate that the maximum error is 10μm without filter compensator modular, and reduced to 5μm with proposed driving power.

A High-Voltage and Low-Noise Power Amplifier for Driving Piezoelectric Stack Actuators.

In this paper, based on the principles of general operational amplifiers, a high-voltage operational amplifier is developed. Considering the influences of piezoelectric stack actuators on the circuit, a novel structure using the high-voltage operational amplifier as a noninverting amplifier is proposed. Because of the simple circuit principles and the voltage feedback control structure, the proposed power amplifier has the advantages of low noise and small size, and it can be realized by discrete electric elements easily. In the application of precision positioning, a power amplifier using the proposed circuit principles for driving piezoelectric stack actuators is designed, simulated, and tested. The simulated results show that the proposed power amplifier could conform to the theory of the circuit. The experimental results show that the designed power amplifier conforms to the simulation, the bandwidth of the power amplifier is about 57 kHz, and the ripple of the power amplifier is less than 2 mV. Furthermore, the output of the proposed power amplifier maintains the same type of wave within in a large range of frequency, while the input is the sinusoidal or square wave, and the resolution of the mechanism which the power amplifier is applied in is about 4.5 nm. By selecting the critical electronic elements and using feedback control, the proposed circuit structure is able to realize a low-cost and high-performance power amplifier to drive piezoelectric stack actuators flexibly, which is the novel work of the paper.