Bias Voltage Source Research Articles

A novel vibrational energy harvester with electric double layer electrets

We propose a new type of vibrational energy harvester with an electric double layer (EDL) electrets. Instead of using any external bias-voltage source or dielectric layer on top of the metal electrode to sustain EDL, we succeed to anchor the ions to polymer network to form the EDL electrets. By changing contact area between the EDL electrets and the electrode, large electric current is generated in the circuit. Owing to extremely large capacitance of the EDL electret, vibrational energy harvesters have the unique capability to leverage the high- density charge accumulation to the electrode and obtained current density becomes as high as 200 μA/cm2 with output voltage of 1V even with low frequency vibrations as low as 1 Hz.

Research of an integrative technique with polarization modulation for generating high-quality multi-wavelength optical source

With the development of society, the need of fiber optical communication expansion and upgrades is increasing. Multi-wavelength optical source has been popularly researched as one of the key component of DWDM. A integrative technique with polarization modulation for high-quality multi-wavelength optical source has been proposed theoretically and experimentally. A comprehensive and systematic overview of how to get a high-quality multi-wavelength optical source, based on in-depth and detailed experiment research. It is found that the optical intensity of the sidebands are not only related to the microwave source and DC bias voltage loaded at EOIM, but also affected by the polarization state of the input light. Five perfect sidebands with equal peak value can be realized by regulating the polarization state of the input light, in addition to regulating the microwave source and DC bias voltage loaded at EOIM as well as. The peak–peak difference of intensity of sidebands can be down to 0.00dBm in the best situation. Polarization state of the input light plays a good role in generating wonderful sidebands with equal space, balanced peak value, high signal-to-noise ratio. The number of sidebands can be selected according to specific application. The findings may have important implications for high-quality multi-wavelength optical source.

An effective energy harvesting method from a natural water motion active transducer

We demonstrated a new water motion active transducer (WMAT) without any external bias-voltage sources or additional processes, which critically limit the use of conventional passive capacitive transducers that convert mechanical motion into electric energy. From a simple structure, we successfully turned on an LED using various kinds of natural water motion. The WMAT, which has wide applicability, has good potential to be a candidate for generating sustainable electric energy.

Pure Al Coatings Prepared by Arc-Added Glow Plasma Depositing Technique and Subsequence Plasma Oxidation

Al coatings were prepared on 316L stainless steel substrate by arc-added glow plasma depositing technique and then plasma oxidized. The influences of bias voltage and arc source current on both the thickness and surface roughness of Al coatings were investigated respectively. Then, the microstructure and the composition of Al and Al2O3 coatings were characterized. Finally, the bonding force and the corrosion resistance of as-prepared alumina coatings were discussed. The results indicated that nanostructured pure Al coatings with surface roughness (Ra) of 267.93 nm were obtained when the bias of the substrate was-300V and the arc current was 70A. The Al2O3 coatings oxidized from nanoAl coatings were dense and uniform, with a bonding force of 37.4 N, an excellent corrosion potential of-0.202V and corrosion current of 0.197 μm·cm-2 in 3.5% NaCl solution.

Effect of Advanced Plasma Source bias voltage on properties of HfO2 films prepared by plasma ion assisted electron evaporation from metal hafnium

HfO2 films, using metal hafnium as starting material, are deposited by plasma-ion assisted electron evaporation with different Advanced Plasma Source (APS) bias voltages. The refractive index and extinction coefficient are calculated, the chemical state and composition, as well as the stress and aging behavior is investigated. Laser induced damage threshold (LIDT) and damage mechanism are also evaluated and discussed. Optical, structural, mechanical and laser induced damage properties of HfO2 films are found to be sensitive to APS bias voltage. The film stress can be tuned by varying the APS bias voltage. Damage morphologies indicate the LIDT of the HfO2 films at 1064nm and 532nm are dominated by the nodular-defect density in coatings, while the 355nm LIDT is dominated by the film absorption. HfO2 films with higher 1064nm LIDT than samples evaporated from hafnia are achieved with bias voltage of 100V.

Drift-Step-Recovery Diode Characterization by a Bipolar Pulsed Power Circuit

A stack of drift- step-recovery diodes (DSRDs) can produce high-voltage pulses with a rise rate of the order of 1 kV/ns. Their building blocks, i.e., the DSRD dies, are designed and manufactured at Soreq Nuclear Research Center based on silicon epitaxial layers. A characterization circuit for DSRDs is presented. The circuit features a power MOSFET, which serves to pump the DSRD in the forward direction and then to pulse it in the reverse direction, and a bias voltage source to balance the forward pumping current with respect to the reverse discharge. Placing the DSRD in series between the MOSFET and the load results in temporal and polarity separation of the MOSFET and DSRD pulses at the load, thus allowing viewing of the net DSRD signal. High-voltage probes are employed to measure the MOSFET and load voltages. Based on this measurement, we formulate the voltage and current extraction of the circuit signals. A 1-ns 190-V epi-Si DSRD die was characterized by this circuit. We show that the DSRD pulses when its reverse discharge is equal to the forward charge, as expected. The DSRD switching loss was measured. An accurate 98% energy balance, which includes the input and output energies with respect to the MOSFET and DSRD switching losses, was obtained. The relationship between the bias voltage, the pumping current, and the main supply voltage is provided. The experimental results are supported by a numerical simulation of the DSRD in the circuit using the Synopsys technological computer-aided design incorporated with a SPICE solver.

Advances for dielectric elastomer generators: Replacement of high voltage supply by electret

Dielectric generators require an external circuit with a high bias voltage source to polarize them. To drastically reduce this circuit and to avoid external polarization, we propose here original transducers combining electrets and dielectric elastomer. Two operating modes have been studied and electromechanical analytical models have been developed from the combination of electrets theory and dielectric model. These concepts are applied on e-textile application: scavenging energy during human motion. An energy density around 6 mJ g−1 is expected on an optimal load of 10 MΩ. More generally, the flexibility, the lightness, the absence of high-voltage supply open many fields of applications beyond e-textiles.

Thermal instability effects in SiC Power MOSFETs

Silicon carbide (SiC) power MOSFETs are characterised by potentially thermally unstable behaviour over a broad range of bias conditions. In the past, such behaviour has been shown for silicon (Si) MOSFETs to be related to a reduction of Safe Operating Area at higher drain–source bias voltages. For SiC MOSFETs no characterisation exists yet. This paper presents a thorough experimental investigation for devices of different voltage classes (600 and 1200V) and different manufacturers, highlighting important differences in electro-thermal performance and failure mode as compared to Si devices. The goal is to derive information for design optimisation and reliable device development for a diverse range of target applications.

Effect of voltage source internal resistance on the SQUID bootstrap circuit

The voltage-biased SQUID bootstrap circuit (SBC) is suitable for achieving simple and low-noise direct readout of dc SQUIDs. In practice, an ideal voltage bias is difficult to realize because of non-zero internal resistance Rin of the bias voltage source. In order to clearly observe the influence of Rin on the SBC parameters (namely the flux-to-current transfer coefficient (∂I/∂Φ)SBC and the dynamic resistance Rd(SBC)) and the noise performance, we introduced an additional adjustable resistor Rad at room temperature to simulate a variable Rin between the SQUID and the preamplifier. We found that the measured SQUID flux noise does not rise, even though Rad increases significantly. This result demonstrates that a highly resistive connection can be inserted between the liquid-helium-cooled SQUID and the room-temperature readout electronics in the SBC scheme, thus reducing the conductive heat loss of the system. This work will be significant for developing multichannel SBC readout systems, e.g. for biomagnetism, and systems using SQUIDs as amplifiers, for example, in TES-array readout.

Design For Test Technique for Leakage Power Reduction in Nanoscale Static Random Access Memory

Problem statement: As technology scales down, the integration density of transistors increases and most of the power is dissipated as le akage. Leakage power reduction is achieved in Stati c Random Access Memory (SRAM) cells by increasing the source voltage (source biasing) of the SRAM array. Another promising issue in nanoscaled devices is the process parameter variations. Due to these variations, higher source voltage causes t he data stored in the cells of the SRAM array to fl ip (weak cell) in the standby mode resulting in hold f ailure. The weak cells identified are replaced usin g redundant columns. Maximum source voltage that can be applied to reduce the leakage power without any failure depends on the number of redundant colu mns available to repair the weak cells. Approach: This study proposes a novel Design For Test (DFT) t echnique to reduce the number of March tests, thus reducing the test time using a source bias (V SB ) predictor. In the proposed method, V SB predictor predicts the initial source bias voltage to be appl ied to the SRAM array. The proposed DFT verified by designing an 8◊16 SRAM array in 90 nm technology. March algorithm was used to identify the weak cells and predict the maximum source voltage from '0' mV. This process was run large number of March tests consuming more test time. Results and discussion: The predicted V SB helps to make a fast convergence of maximum V SB to be applied, which will improve the speed perfor mance of the adaptive source bias and saves the test time by 60 %.

The formation of a p–n junction in a polymer electrolyte top-gated bilayer graphenetransistor

We show simultaneous p- and n-type carrier injection in a bilayer graphene channel by varyingthe longitudinal bias across the channel and the top-gate voltage. The top gate is appliedelectrochemically using solid polymer electrolyte and the gate capacitance is measured to be1.5 µF cm−2, a value about 125 times higher than the conventionalSiO2 back-gate capacitance. Unlike the single-layer graphene, the drain–source current does notsaturate on varying the drain–source bias voltage. The energy gap opened between thevalence and conduction bands using top- and back-gate geometry is estimated.

Adaptive circuits and methods for reducing vibration or shock induced errors in inertial sensors

Adaptive circuits (104,114,118,128,140,160,168) and methods for reducing vibration-induced bias errors in inertial sensors are disclosed. An adaptive circuit for reducing vibration or shock induced errors in an inertial sensor having a proof mass (12,14) and sense electrode (74,76) may include a sense bias voltage source (90), a charge amplifier (80), a means for detecting and/or anticipating an external vibration or shock on the inertial sensor, and a means for selectively dampening the proof masses and/or adjusting the gain sensitivity of the charge amplifier in response to an external vibration or shock on the inertial sensor. A dampening resistive element (108,122) may be provided to dampen the proof mass motion in response to an external vibration or shock on the inertial sensor. Alternatively, or in addition, the gain sensitivity of the rate signal (82,146,150) outputted by the charge amplifier can be adjusted in response to an external vibration or shock on the inertial sensor. During operation, the dampening and/or gain sensitivity can be adjusted to prevent signal saturation or clipping from occurring in the sense electronics, allowing the inertial sensor to continue functioning during periods of vibration or shock.

Dynamically configurable ultrasound transducer with integral bias regulation and command and control circuitry

A dynamically configurable ultrasound transducer element and related circuits and methods. The transducer may comprise an array of capacitive transducer elements, a row decoder coupled to said array of capacitive transducer elements, a column decoder coupled to said array of capacitive transducer elements, a bias voltage source coupled to said row decoder, and a driving signal source coupled to said column decoder. Preferably, a master clock also is provided to allow for a synchronization of signals between the row decoder and column decoder.

The effects of intake pressure, fuel concentration, and bias voltage on the detection of ions in a Homogeneous Charge Compression Ignition (HCCI) engine

Determining when the combustion event occurs in a Homogeneous Charge Compression Ignition (HCCI) engine can prove challenging given that the combustion event is governed by temperature sensitive chemical-kinetics which results in auto-ignition of the fuel/air mixture. Auto-ignition variability can affect emissions and efficiency. Thus, measuring and controlling the combustion event is of the utmost importance. Ion sensors can be used reasonably to detect the combustion event for various fuels used in HCCI engines over a wide range of operating conditions. Experiments have been conducted to measure ion signals produced from the combustion of gasoline, ethanol, and n-heptane in a 4-cylinder HCCI engine with different equivalence ratios and intake pressures. It was found that the ion signal is reduced under several situations: with an increase in intake pressure, reducing equivalence ratio (under lean conditions), and decreasing the bias voltage source. Results from a Well-Mixed-Reactor (WMR) model suggest that gasoline and ethanol produces more ions than n-heptane during combustion under the same operating conditions; these predictions are supported by experiments.

Switch-controllable OTRA-based bistable multivibrators

Two bistable multivibrators based on the operational transresistance amplifier (OTRA) are presented. The first topology consists of only one OTRA and a positive feedback network. The second multivibrator utilises a single-pole double-throw (SPDT) switch along with a bias voltage source to shift the hysteresis loop into either the right-half-part or the left-half-part of the νi–νo plane. These two proposed circuits have a common attractive feature. That is, both clockwise and counter-clockwise hysteresis operations can be fulfilled with an additional SPDT switch connected to different configurations. In order to extend the applications, a general multiple-output configuration is also suggested. The presented bistable multivibrators are simple and versatile. The operation principles are described in detail. Theoretical analyses are verified by the experimental results on the prototype circuits.

Synthesis and characterization of nano-composite Ti–Si–N hard coating by filtered cathodic arc deposition

Nano-composite Ti–Si–N films were deposited on tungsten carbide substrates by a filtered cathodic arc deposition system using TiSi-alloy as arc sources. The influences of bias voltages on the microstructure, mechanical and corrosion properties of the films were investigated. Field emission scanning electron microscope, atomic force microscopy, X-ray diffractometer, X-ray photoelectron spectroscopy, high-resolution electron probe microanalyzer, polarization and immersion tests were employed to identify microstructures and properties of Ti–Si–N films. Both magnetic 90°-filter duct arc source and substrate bias voltage have important effects on the surface roughness, microstructure and corrosion properties of Ti–Si–N coatings. The results showed that both the increase of Si content and decrease of grain size resulted from the increase of substrate bias voltage. The microhardness of the coatings was enhanced by increasing substrate bias voltage. The corrosion resistance of coatings tested in 1 N H 2SO 4 solution confirmed that Ti–Si–N coatings with a magnetic 90°-filter duct arc source were better than Ti–Si–N coatings without a magnetic 90°-filter duct arc source due to the effect of reducing microparticles. On the other hand, the corrosion resistance is also increased with reducing surface roughness of Ti–Si–N films, which can be controlled by substrate bias voltage in deposition process.

Analysis of Spatiotemporal Patterns in an Infinite-Dimensional Electromagnetic System

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> An infinite-dimensional electromagnetic system is proposed as a practical model for analyzing the spatiotemporal chaos. The system consists of a linear lossless transmission line connected to a p-n-junction diode in series with a dc bias voltage source at one end and to an active linear resistor at the other end. The temporal dynamics of the backward-traveling voltage wave is investigated by using a corresponding one-dimensional map, and the effects of the serial dc bias voltage source on the dynamics of the system are particularly studied here. Numerical results are presented to show that the spatiotemporal nonlinear oscillation of the voltages along the lossless transmission line is the oscillation of isotropism with respect to space and time, and spatial intermittency and chaos exist in this infinite-dimensional electromagnetic system. Several spatiotemporal patterns of the voltages are also observed. </para>

CONTROLLING INSTABILITIES OF HYDROGENERATED a-Si:H TFT UNDER BIAS TEMPERATURE STRESSING

The hydrogenerated amorphous silicon a-Si:H thin film transistors TFT with silicon nitride as a gate insulator have been stressed with independently varying gate (Vg), source (Vs), and gate-source (Vgs) bias voltage in order to elucidate the instability mechanism and suggest the new a-Si:H TFT structure. It was found that there was dependency of threshold voltage shift not only on Vgs, but also on Vg and Vs, which had not ever been reported. Its shift amount increased with increasing Vs and/or Vg. In this reports, we suggested the new TFT device structure to eliminate the dependency of Vth shift on Vg and Vs and found that with the new suggested TFT structure, the Vth shift controlling factor can only be Vgs.

Radon measurements with a PIN photodiode

Silicon photodiodes are well suited to detect alphas coming from different sources as neutron reactions or radon daughters. In this work a radon in air detecting device, using an 18×18 mm silicon PIN photodiode is studied. The ionized airborne decay products formed during radon diffusion were focused by an accelerating high voltage to the PIN surface. Several conducting rings were disposed inside a cylindrical PVC vessel in such a way that they reproduced the electric field created by a punctual charge located behind PIN position. Alpha spectra coming from the neutral and ionized species deposited on the PIN surface, dominated by 218Po and 214Po progeny peaks, were recorded for varying conditions. Those include radon concentration from a Pylon source, high voltage (thousands of volts) and PIN inverse bias voltage. Different parameters such as temperature and humidity were also registered during data acquisition. The increase in the particle collection efficiency with respect to zero electric field was compared with the corresponding to a parallel plates configuration. A discussion is made in terms of the most appropriate voltages for different radon concentrations.

Self-Sensing Active Magnetic Bearings Using a New PWM Amplifier Equipped with a Bias Voltage Source

In this paper, a self-sensing active magnetic bearing (AMB) with a new PWM amplifier is proposed. This amplifier employs two DC sources: one supplies a control current and the other supplies a bias current. A pair of electromagnets driven by this amplifier also works as a position sensor based on bridge measurement. In the experiment, a rotor running at 45,000 min-1 is suspended by the proposed 5-axis AMB without any position sensors. The experimental system is still stable even if the length of the cables between the PWM amplifiers and the electromagnets is varied within 45 meters.