Electronic Resistor Research Articles

Fabrication of submicron CoFeB/MgO/CoFeB magnetic tunnel junction using a resistive mask HSQ/PMMA

The technology of manufacturing magnetic tunnel junctions based on CoFeB/MgO/CoFeB layers with characteristic lateral dimensions from 200 to 700 nm using a combination of HSQ/PMMA electronic resistors has been developed. To study the processes of magnetization reversal in the obtained samples, measurements of magnetoresistance curves were carried out. It is shown that, depending on the structure of the magnetically sensitive layer and the geometric parameters of the TMR contacts, elements with both vortex and quasi-homogeneous distribution of the magnetization of the free layer are realized. At the same time, in the latter, the width of the magnetization reversal front is from 2 to 6 Oe.

A novel high-performance three-phase magnetic field energy harvester for powering up vehicle onboard electronics

The boosting development of vehicle electrification and onboard sensing networks in the intelligent vehicle era poses a significant challenge to conventional electrical power supply systems. This study developed a novel passive three-phase magnetic field energy harvester (TMEH) for reliable and sustaining power to drive vehicle onboard electronics, which recycles the induced magnetic field energy around the power lines of a permanent magnet synchronous motor (PMSM) on an electric vehicle (EV). A Y-Y topological connection pattern for three-phase coils was designed to enhance and stabilize the TMEH output performance. Furthermore, three auto-shift operating modes were assigned to the TMEH to tackle the dynamic changes of the captured power caused by unpredictable vehicle manoeuvres and road conditions. The theoretical model and numerical method were also established for structural optimization of the TMEH, followed by a series of experimental tests for highlighting the impacts of the power lines carrying alternating current on TMEH. The results have indicated that the proposed TMEH showed impressive energy conversion efficiency, providing an independent power supply for sensors and other electronics applications on a 4 kW-PMSM driven EV. Bench testing results and practical EV driving trials demonstrated the capability of the TMEH prototype to power up multiple types of sensors and electronic devices under most EV driving conditions. Specifically, an average power of 5.69 W and power density of 123.85 mW/cm3 were generated by the harvesting coils when excited by a 50 A current at 50 Hz. Furthermore, the maximum TMEH energy conversion efficiency of 41.9% at the excitation current frequency of 50 Hz is obtained in laboratory conditions. In EV driving tests at speeds of 20–30 km/h, the TMEH presented steady output power up to 5.98 W, capable of driving various loads such as an electronic resistor, Li-ion battery, GNSS/INS device, driving recorder, and cellphone, either with the employment of one or two sets of harvesting coils. The approach of this study offers a promising application scenario to power up numerous electronics on a commercial transport EV platform driven by a more powerful PMSM.

Elektronik Olarak Ayarlanabilen FDCCII Tabanlı Yeni Memkapasitör Emülatör Devresi

Since memcapacitor and meminductor elements have not been produced yet, emulator circuits are used to examine their application areas. In this paper, a new FDCCII-based grounded memcapacitor emulator circuit is presented. The proposed circuit consists of one FDCCII, one multiplier, three capacitors and two MOSFETs. These two MOSFETs are utilized as electronic resistors in the circuit. The variable part of memconductance can be adjusted electronically and the proposed memcapacitor possesses an incremental-decremental adjustable structure. Moreover, it contains fewer active elements than many memcapacitor emulator studies in the literature. The proposed circuit was designed in LTspice, and frequency response, temperature, and Monte Carlo analyses were performed. In addition, the electronic resistor has been simulated at various values, demonstrating that the circuit is electronically adjustable. The simulation results are consistent with the mathematical results presented in the article.

Investigation of Roughness Correlation in Polymer Brushes via X-ray Scattering.

Thin polymer films and coatings are used to tailor the properties of surfaces in various applications such as protection against corrosion, biochemical functionalities or electronic resistors. Polymer brushes are a certain kind of thin polymer films, where polymer chains are covalently grafted to a substrate and straighten up to form a brush structure. Here we report on differences and similarities between polymer brushes and spin-coated polymer films from polystyrene and polymethyl methacrylate with special emphasis on surface roughness and roughness correlation. The phenomenon of roughness correlation or conformality describes the replication of the roughness profile from the substrate surface to the polymer surface. It is of high interest for polymer physics of brush layers as well as applications, in which a homogeneous polymer layer thickness is required. We demonstrate that spin-coated films as well as polymer brushes show roughness correlation, but in contrast to spin-coated films, the correlation in brushes is stable to solvent vapor annealing. Roughness correlation is therefore an intrinsic property of polymer brushes.

An electronically controllable, fully floating memristor based on active elements: DO-OTA and DVCC

In this paper, we have presented a Dual-Output Operational Transconductance Amplifier (DO-OTA) and Differential Voltage Current Conveyor (DVCC)-based fully floating emulator which enables the memristor current to flow in both directions when used with other circuit elements. The proposed memristor consists of only one DO-OTA, one DVCC, one grounded capacitor that is attractive for an integrated circuit, and two PMOS transistors operating as an electronic resistor. The proposed fully floating memristor emulator includes two very important features: (1) the fixed and variable memductance parts of the circuit are electronically adjustable, and (2) both incremental and decremental circuit behaviors can be obtained without altering the circuit topology. The circuit was laid using the Cadence Spectre Analog Environment with TSMC 0.18 µm process parameters and occupied a layout area of only 119 µm × 90 µm. The post-layout simulation results for the memristor circuit were obtained for different operating frequencies and all simulations were fully compatible with the experimental memristor behaviors. Finally, the memristor circuit was built on a breadboard using discrete circuit elements, and all experimental results were also compatible with the expected memristor characteristics.

Emergence of electronic conduction in bismuth oxide eletrolyte under high pressure

The ionic transport properties of bismuth oxide (Bi2O3) were investigated under high pressures with impedance spectrum and Raman spectrum measurements. It was found that Bi2O3 is a pure ionic conductor below 9.0 GPa. Its pressure-dependent ionic conduction is determined by the diffusion rate of O2− ions. Above 9.0 GPa, the number of O2− ions that participate in electrical transportation are reduced rapidly by the pressure-induced distortion of crystal lattice, which becomes the essential factor to affect the ionic conduction. Most importantly, electronic conduction began to appear in the transportation process and coexist with the ionic conduction at 9.0 GPa indicating a few of originally localized electrons are involved in the electrical transportation due to the enhancement in distorted intension of Bi polyhedrons. Meanwhile, from the impedance spectra studies, it was also known that the electrical transport behaviors of Bi2O3 can be tuned by the frequency of input signals. At high frequencies, Bi2O3 behaves like an ionic solid electrolyte, but at low frequencies, it behaves like an electronic resistor.

DESIGN AND CONSTRUCTION OF AN AUTOMATIC ENERGY EFFICIENCY DEVICE FOR INDUSTRIAL AND DOMESTIC APPLICATIONS

Energy is the key driver of macroeconomic growth. As the very basis of development, energy usage is closely related to the level of productivity in the industries, commercial establishments, offices and in our domestic homes activities. This paper present the design and construction of an automatic energy efficiency device. This is necessary to ensure that energy is affordable and our electrical appliances are intelligently used by, providing automatic control to major energy consuming equipment. The method used is the design and construction of the device with various electronic component like, microcontroller, transistors, diodes, resistors and sensors but, to mention but a few. The various units were connected together, soldered and finally coupled. The microcontroller is programmed with assembling language. Test were made to ensure that the various units delivered the specified input and output in line with design specifications. The device was integrated into an office with two lighting points and the results showed that the device performed efficiently well. The cost implication of the design and construction of the automatic energy efficiency device is about one hundred and fifty US dollars ($150), equivalent of thirty five thousand naira (#35,000) only.

Electronic resistor emulators for ferroresonance damping in MV transformers

The occurrence of ferroresonances, due to the presence of voltage transformers in isolated-neutral in medium-voltage (MV) distribution grids, results in overvoltages and overcurrents that may damage the connected equipment. To prevent this phenomenon, the protection windings of the MV transformers have to be properly loaded for damping purposes. Mitigation equipment based on resistors, passive/active circuits and static converters have been proposed in the literature. This study proposes a new variety of mitigation equipment based on very simple power electronic converters operated as configurable resistor emulators. The proposed approach is evaluated theoretically and validated experimentally. A resistor emulator proof of concept is designed and applied for damping ferroresonances due to the occurrence of line-to-ground faults in isolated-neutral MV distribution power systems.

Versatile tunable current-mode universal biquadratic filter using MO-DVCCs and MOSFET-based electronic resistors.

This paper presents a versatile tunable current-mode universal biquadratic filter with four-input and three-output employing only two multioutput differential voltage current conveyors (MO-DVCCs), two grounded capacitors, and a well-known method for replacement of three grounded resistors by MOSFET-based electronic resistors. The proposed configuration exhibits high-output impedance which is important for easy cascading in the current-mode operations. The proposed circuit can be used as either a two-input three-output circuit or a three-input single-output circuit. In the operation of two-input three-output circuit, the bandpass, highpass, and bandreject filtering responses can be realized simultaneously while the allpass filtering response can be easily obtained by connecting appropriated output current directly without using additional stages. In the operation of three-input single-output circuit, all five generic filtering functions can be easily realized by selecting different three-input current signals. The filter permits orthogonal controllability of the quality factor and resonance angular frequency, and no inverting-type input current signals are imposed. All the passive and active sensitivities are low. Postlayout simulations were carried out to verify the functionality of the design.

Time-Average Velocity and Turbulence Measurement Using Wireless Bend Sensors in an Open Channel with a Rough Bed

This paper is motivated by the need to develop low cost, wireless velocity sensors for hydraulic research and application in streams. A velocity bend sensor (VBS) is a flexible plastic polyimide substrate sheet with an electronic resistor connected to a voltage divider. Drag of a moving fluid bends the sensor, changes the electronic resistance, and produces a voltage drop that can be related to the time-averaged freestream velocity of the fluid. VBSs were tested in a recirculating hydraulic flume with a gravel bed. The VBSs show transition from rigid to elastic bending with increasing freestream velocity, which can be described using dimensionless fluid and beam- bending properties. The relationship between stream velocity and voltage drop across the circuit is nonlinear. A semitheoretical approach to estimate time-averaged streamwise velocity from the voltage drop based on fluid drag, elastic member bending, and circuit principles is applied and shows good agreement with experimentally derived calibration curves. The triple decomposition theorem and spectral analysis are performed on VBS and acoustic Doppler velocimeter (ADV) time series. Results show that the VBS captures low-frequency character- istics of macroturblence present within the turbulent open channel flow but is unable to measure smaller-scale characteristics of eddy shed- ding for these hydraulic conditions. Turbulent intensity calculated using VBS data is 12% of that from the ADV attributed to the lack of detection of shedding-sized eddies. But, the linear fit between turbulent intensity from the VBS and ADV suggests that the VBS can be used as a proxy for more detailed turbulent measurements when applied in streams. DOI: 10.1061/(ASCE)HY.1943-7900.0000725. © 2013 American Society of Civil Engineers. CE Database subject headings: Probe instruments; Decomposition; Spectral analysis; Turbulence; Open channels; Velocity; Flow measurement.

DVCC-based Electronically Tunable First-Order Current-mode Filters

The advent of differential voltage current conveyor (DVCC) has opened up new avenues in analog circuit design. In the present work, a DVCC has been employed to design currentmode first-order continuous-time analog filters. Parameter tunability is achieved by the use of a two-MOSFET electronic resistor which exhibits variation in resistance in accordance with a control voltage. The proposed circuits are amenable for monolithic integration by virtue of the fact that only MOSFETs and grounded capacitors are utilized. Circuit simulations using PSPICE yielded promising results.

All‐pass filters using DDCC‐ and MOSFET‐based electronic resistor

AbstractThe main motivation in this paper is to draw attention to the tunability and input‐signal amplitude limitations when a nonlinear device is used as a resistor. For this purpose, two first‐order all‐pass filters are proposed using differential difference current conveyor (DDCC), a capacitor and a resistor without element‐matching restriction. These all‐pass filter circuits can be made electronically tunable with electronic resistors. Tunability and input‐signal amplitude limitations of the proposed circuits due to the operational restrictions of the electronic resistors are examined. PSPICE simulations confirm the validity and the practical utility of the proposed circuits. Copyright © 2010 John Wiley & Sons, Ltd.

A novel phase shifter using two NMOS transistors and passive elements

In this paper, a new voltage-mode configuration for realizing a first-order phase shifter is suggested. The proposed phase shifter contains low number of components, i.e. two n-type metal-oxide semiconductor field effect transistors (NMOS transistors) both operating in saturation region, a grounded capacitor and three resistors. The presented circuit can be equipped with electronic tunability by using externally controllable electronic resistor. Computer simulation results, using SPICE program, are given to demonstrate the performance of the proposed phase shifter.

The Corrosion of Electronic Resistors

Precision thick chip resistors are used in a variety of different industries, from telecommunications to automotive electronics, and as such can be exposed to mild and aggressive corrosive environments. This paper investigates the corrosion performance of two generic precision thick chip resistors in a controlled corrosive atmosphere consisting of 60degC, 4 ppm H2S and water vapor in purified air. The resistors were exposed in an environmental chamber for periods of 5, 10, 15, 30, and 60 days. Following exposure, the samples were cross sectioned and subjected to surface analysis using microscopy and microanalysis. After the initial stages of exposure, corrosion was observed on only one of the two types of resistors. The corrosion developed because H2S gas and water vapor diffuses through the thin protective organic layer on the resistor, and subsequently reacts with the silver conductor layer. Corrosion was facilitated by poor overlapping of the solder and nickel layer and, in particular the glass binder over the glass overcoat, which allowed silver and sulphur to diffuse along the interface. In addition, this poor overlapping allowed contact between the nickel layer and the silver layer resulting in the development of an electrochemical corrosion cell. The main corrosion products that developed were silver sulfide (Ag2S) and nickel sulphur residue.

Musical signals from Chua's circuit

Chua's circuit can produce a very rich variety of signals that are both periodic and chaotic. The authors explore some classes of these attractors with respect to their auditory display and musical properties. They discuss the fast control of the circuit through a specially developed computer-controlled electronic resistor and how chaotic control methods might be applied to optimally switch between different attractors. The Chua circuit has parameter regions where noisy frequency and amplitude modulated sounds are generated, each of which is related to a certain transition to chaos. The authors discovered a period-adding sequence of bassoon-like sounds that produces interesting almost harmonic pitch changes. Finally, they emphasize the importance of transient dynamics especially in the context of percussion-like sounds. >

A Useful Infrared Source

Reliable Inconel-sheathed cartridge heaters rated at hundreds or thousands of watts have been in use for many years. Miniature heaters have been manufactured, having axial leads, which when treated with an emissive coating meet or exceed Globar emissivities in the ir. Free-air temperatures approximating 800 degrees C have been obtained for power inputs of 10 W, while temperatures as high as 1150 degrees C are possible for short lifetimes, e.g., 10 h, at power dissipations of 24 W or more. Sources can be designed to operate from d or ac power with higher voltages and lower currents depending upon physical size limitations, resulting in simplified power supply problems. Although voltages from 12 V to 230 V are practical for larger units, the sources described below operated at 1060 degrees C from a nominal 1.07 A at 18.7 V d for apower consumption of 20 W variable continuously about this value. The small dimensions of these sources compare favorably to those of a 0.5-W electronic resistor. The present units are cylindrical, 1 cm long x 4 mm diam. The construction of smaller units is possible bt difficult under present state-of-the-art limitations.

Adjusting resistors in an electronic way

In this paper a method is described for adjusting electronically the value of a resistor. The method is based on the time-division principle. Switching a resistor << onand << offhigh-frequency the effective mean value of the conductivity is proportional to the relative << on -time. There are several possibilities of application for these electronic resistors. Here we will discuss the realization of the coefficients of an operational amplifier by means of electronic resistors. In this investigation the usual d.c. high gain amplifier of an operational amplifier has been replaced by an electronic comparator. This has been done to enable the use of the two-level output signal of the operational amplifier or a signal obtained from it by some logic operation for controlling one or more electronic resistors. For some examples we will show that one-and more-dimensional non-linear functions can be generated in this way.