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This paper presents two novel measurement methods to characterize silicon carbide (SiC) MOSFET devices. The resulting data are utilized to significantly improve the extraction of a custom device model that can now accurately reproduce device switching behavior. First, we consider the $I_{\text{d}}- V_{\text{ds}}$ output characteristics of power devices such as SiC transistors. These are typically measured using traditional curve tracers, but the characterization of the high-voltage and high-current (HVHC) region is very challenging because of device power compliance and self-heating. In this paper, we introduce a measurement technique that overcomes self-heating and derives the HVHC region from switching waveforms. The switching transient characteristics of devices are used to determine drain current $(I_{\text{d}})$ as a function of drain–source voltage $(V_{\text{ds}})$ in the HVHC range. Second, we consider another challenging characterization area: measurement of nonlinear capacitances when device is turned on. These capacitance characteristics of on-state devices are important for correcting disagreements between simulations and measurements in turn-off switching transient waveforms and cannot be measured using a conventional capacitance-voltage meter. We introduce S-parameter measurements as an effective method to obtain the capacitance characteristics of both off-state devices and on-state devices. These novel measurement techniques have been applied to the modeling of a SiC device. The extracted device model, a modified version of the popular Angelov−GaN high-electron-mobility transistor model, shows significant improvement in terms of the accuracy of switching waveforms of devices over a wide range of operating conditions. [ABSTRACT FROM AUTHOR]

Currently, proper vehicle head restraint (HR) positioning requires manual adjustment and knowledge on the part of the occupant. By removing the requirement for manual adjustment, an HR positioning system that autonomously moves and adapts the HR position properly to any seated occupant could serve to reduce the social and personal costs of whiplash injuries, as compared with existing manual systems. To achieve this, quantification of the occupant's head position relative to the HR is required. In a previous paper, a rectangular capacitive proximity-sensing array for the purpose of occupant head position quantification was studied. Here, a range-maximized sensor was first designed to reduce electrostatic and environmental disturbances. To achieve this, numerical modeling and laboratory experiments were conducted, and then, a design process for an interdigitated comb-shaped sensor geometry was proposed to maximize the sensing range of the sensor. The effects of temperature and humidity on the sensor were also evaluated and compensated. A novel capacitive proximity-sensing array was then designed, which had the minimum number of the aforementioned comb-shaped sensors necessary for accurately estimating the 3-D position of an occupant's head in near real time. This estimation was carried out using a nonparametric neural network. The above capacitive array was then integrated and fully contained in a customized HR as part of a vehicle seat safety system. The system was tested and demonstrated that such a head position sensing methodology would be capable of autonomously positioning an HR to meet the guidelines of the Insurance Institute for Highway Safety (IIHS). [ABSTRACT FROM PUBLISHER]

Nowadays, the miniaturization of the passive components is the major challenge in the better integration of electronic circuits in portable devices. This paper presents the simulation, the modeling, the manufacturing, and the characterization of a face to face transformer where conductors are buried in the magnetic layer and where the transformer’s primary and secondary windings are turned in the plane by 45°. The buried conductors allow the inductor magnetizing to be increased by a ratio of 50%. The turn of the transformer’s primary and secondary windings allows the capacitance coupling to be decreased by a ratio of 100%. Simulations are made by using the high-frequency structural simulator, which is 3-D finite-element software. Measurements are performed for frequencies ranging from 40 Hz to 300 MHz by an impedance meter and a vector network analyzer. Good consistency between the simulation and measurement is obtained. [ABSTRACT FROM AUTHOR]

A new capacitance-to-digital converter (CDC) that gives a digital output proportional to the measurand kx , independent of its nominal capacitance, is reported in this paper. Various CDCs are available in the market, but their output is a function of the nominal value C_{0} of the sensor. Thus, a manual correction is required in the output, whenever a new capacitive sensor is interfaced to such CDCs. Moreover, the C_{0} of the sensors is usually a large value compared with the change in capacitance due to kx . Thus, in a typical CDC, a large percentage of the output counts/bits is used to measure and represent the C_{0} leading to an underutilization of the hardware as far as the measurement of kx is concerned. The proposed CDC uses a new automatic calibration (AC), employing a switched-capacitor (SC) circuit-based voltage source in a feedback topology, and provides an output independent of the C0 of the sensor employed. The proposed CDC is based on an SC dual-slope technique and possesses the advantages of the dual-slope conversion method. The CDC circuit is designed such that the entire full scale can be used for representing the change in the kx . In addition to this advantage, the AC helps to remove the dependence on the accuracy of the reference capacitor employed in the CDC. A detailed analysis of the effect of various sources of errors in the CDC has been conducted and presented in this paper. A prototype of the proposed CDC has been developed and tested. The results obtained show that the output of the CDC is not a function of the C0~(C0 varied from 60 pF to 1.46 nF) of the sensors interfaced. [ABSTRACT FROM AUTHOR]

This paper describes the use of a focused aircoupled capacitance transducer combined with pulse compression techniques to form high-resolution images of thin materials in air. The focusing of the device is achieved by using an off-axis parabolic mirror. The lateral resolution of the focused transducer, operating over a bandwidth of 1.2 MHz, was found to be less than 0.5 mm. A combination of the focused transducer as a source and a planar receiver in through-transmission mode has been developed for the measurement of different features in paper products, with a lateral resolution in through-transmission imaging of ∼0.4 mm. Images in air of thin samples such as bank notes, high-quality writing paper, stamps, and sealed joints were obtained without contact to the sample. [ABSTRACT FROM AUTHOR]

In this paper, a regenerative electromagnetic brake, which has the same structure as conventional electromagnetic brakes and the same principle as self-excited induction generators, is introduced, and a miniature model is designed. The most important part of the design stage is to choose proper equivalent circuit parameters for self-excitation within a given operating speed range. This paper describes a 3-D map, called a CN-map, that consists of the rotating speed, capacitance, and stator resistance to verify the possibility of self-excitation during the design stage. A miniature model is designed using the map, and the experimental results obtained with the miniature model confirm the feasibility of the design process. [ABSTRACT FROM AUTHOR]

This paper deals with the deep characterization of a novel electrical parasitic effect in AlGaN/GaN technology so called “electrical runaway mechanism.” It is characterized by an anomalous gate current behaviour. Electrical measurements versus temperature show that the runaway mechanism threshold is temperature independent on the contrary to the gate current progression as a function of \mathrm V\mathrm{DS} . Optoelectrical measurements show that the physical mechanism inducing the runaway mechanism occurs below the gate area. Then, reliability aging tests performed in the frame of a 0.5- \mu \textm GaN technology present the runaway mechanism as a wear out mechanism. Finally, the runaway mechanism has been associated with tunnel conduction through gate metal and AlGaN layer. [ABSTRACT FROM PUBLISHER]

This paper explores the performance of asymmetrical dual-k underlap spacer (ADKUS) SOI FinFET (device-D1) over the wide temperature range (200 K-450 K). An attempt has been made to find out the zero temperature coefficient (ZTC) biased point to enhance the digital, analog and RF performance at 20 nm channel length. The proposed device will be suitable for VLSI circuit’s design, internet of things (IoT) interfacing components and algorithm development for security applications of information technology. The potential parameters of device-D1 like intrinsic gain (AV ), output conductance (gd ), transconductance (gm ), early voltage (VEA ), off current (Ioff), on current (Ion), Ion/Ioff ratio, gate to source capacitance (Cgs), gate to drain capacitance (Cgd), cut-off frequency (fT), energy (CV²), intrinsic delay (CV/I), energy-delay product (EDP), power dissipation (PD), sub-threshold slope (SS), Q-Factor (gm,max/SS), threshold voltage (Vth) and maximum transconductance (gm,max) are subjected to analyze for evaluating the performance of ADKUS SOI FinFET for wide temperature environment. The validation of a temperature based performance of ADKUS SOI FinFET gives an opportunity to design the numerous analog and digital components of internet security infrastructure at wide temperature environment. These ADKUS SOI FinFET based components give new technology to the IoT which has the ability to connect the real world with the digital world and enables the people and machines to know the status of thousands of components simultaneously. [ABSTRACT FROM AUTHOR]

In this paper, we present a high-efficiency transmitter based on an integrated circuit (IC) supply modulator implemented in the same 0.15- $\mu \text{m}$ gallium nitride (GaN)-on-SiC RF process as the power amplifier (PA) monolithic microwave IC. The X-band 10-W two-stage PA is designed for stable operation with minimal drain capacitance, which enables fast supply modulation. The multilevel supply modulator provides eight voltage levels with 3-bit digital control [(power digital-to-analog converter (pDAC)], achieving a state-of-the-art slew rate of 5 kV/ $\mu \text{s}$. Characterization of the dynamic $R_{\mathrm{\scriptscriptstyle ON}}$ of the GaN switches allows the development of an efficiency model for the pDAC and an investigation of the effects of the pDAC internal resistance on the PA performance, resulting in a comprehensive efficiency model for the supply-modulated PA. The flexible compact transmitter consisting of the PA and pDAC ICs shows high efficiency in backoff for a variety of signals, both for radar and communications. Measured results for amplitude- and frequency-modulated radar pulses show a composite power-added efficiency (CPAE) of 44% with a peak power of 10 W at 9.57 GHz, with simultaneous spectral confinement and 52-dB improvement of the first time sidelobe. For a 20-MHz high peak-to-average ratio LTE signal, the CPAE increases from 11% to 32% compared to a fixed supply voltage transmitter, while linearity under dynamic supply operation is maintained through digital predistortion. [ABSTRACT FROM AUTHOR]

Electrical capacitance tomography (ECT) attempts to image the permittivity distribution of an object by measuring the electrical capacitance between sets of electrodes placed around its periphery. Image reconstruction in ECT is a nonlinear ill-posed inverse problem, and regularization methods are needed to stabilize this inverse problem. The reconstruction of complex shapes (sharp edges) and absolute permittivity values is a more difficult task in ECT, and the commonly used regularization methods in Tikhonov minimization are unable to solve these problems. In the standard Tikhonov regularization method, the regularization matrix has a Laplacian-type structure, which encourages smoothing reconstruction. A Helmholtz-type regularization scheme has been implemented to solve the inverse problem with complicated-shape objects and the absolute permittivity values. The Helmholtz-type regularization has a wavelike property and encourages variations of permittivity. The results from experimental data demonstrate the advantage of the Helmholtz-type regularization for recovering sharp edges over the popular Laplacian-type regularization in the framework of Tikhonov minimization. Furthermore, this paper presents examples of the reconstructed absolute value permittivity map in ECT using experimental phantom data. [ABSTRACT FROM AUTHOR]

This paper addresses shaft end-to-end and shaft-to-frame voltages that appear in the 400-V, 15-kW induction motor driven by a voltage-source pulsewidth modulation (PWM) inverter. A shaft-to-frame voltage can be observed at either shaft end with respect to the grounded motor frame. A shaft end-to-end voltage can be observed as a voltage difference between the shaft-to-frame voltage at the drive end (DE) and that at the nondrive end (NDE). Experimental waveforms lead to the following interesting observations: motor internal coupling and parasitic capacitance, along with the high-frequency common-mode voltage generated by the PWM inverter, cause a shaft-to-frame voltage with a peak of 8 Vat both DE and NDE. When the shaft-to-frame voltage at either DE or NDE exceeds a dielectric breakdown voltage of thin bearing lubricating grease films, a shaft end-to-end voltage with a peak of 2 V and a width of 30 ns occurs along the motor shaft. This paper makes experimental discussions on the shaft end-to-end voltage generation. Installing a differential-mode filter and/or a common-mode filter on the motor drive system gives a hint on the mechanisms of the occurrence of the shaft end-to-end voltage. [ABSTRACT FROM AUTHOR]

This paper presents a complete circuit-compatible compact model for single-walled carbon-nanotube field-effect transistors (CNFETs) as an extension to Part 1 of this two-part paper. For the first time, a universal circuit-compatible CNFET model including the practical device nonidealities is implemented with HSPICE. In addition to the nonidealities included in the companion paper, this paper includes the elastic scattering in the channel region, the resistive source/drain (S/D), the Schottky-barrier resistance, and the parasitic gate capacitances. More than one nanotube per device can be modeled. Compared to silicon technology, the CNFETs show much better device performance based on the intrinsic CV/I gate-delay metric (six times for nFET and 14 times for pFET) than the MOSFET device at the 32-nm node, even with device nonidealities. This large speed improvement is significantly degraded (by a factor of five to eight) by interconnect capacitance in a real circuit environment. We performed circuit-performance comparison with all the standard digital library cells between CMOS random logic and CNFET random logic with HSPICE simulation. Compared to CMOS circuits, the CNFET circuits with one to ten carbon nanotubes per device is about two to ten times faster, the energy consumption per cycle is about seven to two times lower, and the energy-delay product is about 15-20 times lower, considering the realistic layout pattern and the interconnect wiring capacitance. [ABSTRACT FROM AUTHOR]

This paper presents accurate analytical models to calculate the electrostatic gate capacitance of 1-D field-effect transistors (FETs) with multiple cylindrical conducting channels. Gate capacitance Cgg is decomposed into three major components: 1) capacitance Cgc between the gate and the parallel cylindrical conducting channels (the number of channels ≥ 1) in dual-layer dielectric materials; 2) outer fringe capacitance Cof between the gate and the source/drain cylinder conductors; and 3) coupling capacitance Cgtg between the adjacent gates. A realistic planar-gate structure with high-k gate dielectric material is considered in this paper, including the screening effect of the parallel conductors and different dielectric materials on capacitance. An accuracy of 10% is achieved from the analytic models, compared with the values that were simulated by 3-D numerical field solvers. Using a simple analytical expression for the gate delay that includes the parasitic capacitance and screening of multiple parallel conducting channels, this paper also shows that both increasing the number of channels per gate and reducing the gate height are effective ways to improve device speed. [ABSTRACT FROM AUTHOR]

This paper presents an analysis and design of an electronic load controller (ELC) for three-phase self-excited induction generators (SEIGs) suitable for stand-alone pico-hydro power generation with constant input power. Here, the SEIG can be used to generate constant voltage and frequency if the electrical load is maintained constant at its terminals. Moreover, under such operation, SEIG requires constant capacitance for excitation resulting in a fixed-point operation. For this purpose, a suitable control scheme has to be developed such that the load on the SEIG remains constant despite change in the consumer load. In such applications, water is freely available and, hence, a simple and cheap controller has to be developed, which can operate almost unattended in remote and hilly regions. The proposed ELC consists of an uncontrolled rectifier and chopper with a series ‘dump’ load. Proper design of rectifier, chopper, and dump load is very important for troublefree operation of ELC. In this paper, an analysis along with a design procedure for computing the rating of various components of ELC is presented for a range of SEIGs. [ABSTRACT FROM AUTHOR]

Essential task for companies in these days is to reduce operating costs and optimization of workflow processes of machines, in order to increase the competitiveness and productivity. Telematics systems is relatively widespread and utilized for fleet management and enables collecting a wide range of operating parameters. One of the monitored parameters of operating costs is fuel consumption of machines. The collection of data on fuel consumption can be realized using various methods. By default, the fuel consumption data is transmitted from CAN-BUS which does not always coincide with the value of the real fuel consumption. Another possible way of fuel consumption monitoring is realized via installation of capacitance probe mounted directly into the fuel tank. The principle of measurement of these two methods is different, and each method has its own specifics. For instance, a capacitive probe enables detection of nonstandard decreases of fuel level in the fuel tank. The aim of this paper is to compare the methods of fuel consumption measuring via the CAN-BUS and utilization of capacitive fuel probe. Measuring unit Gcom was used for collecting data which sends data of fuel consumption to the server in real-time. The purpose of this paper is to prove or disprove the hypothesis that measured fuel consumption is statistically significant between measuring via CAN-BUS compared to capacitance probe. [ABSTRACT FROM AUTHOR]

One of the challenges concerning proton exchange membrane fuel cell (PEMFC) is how to control the air compressor voltage so that enough oxygen is provided for reaction, while the net power (the produced electrical power minus the air compressor used power) is maximized. Another challenge is the enhancement of the PEMFC lifespan by controlling the inlet hydrogen flow in a way that enough hydrogen is provided for reaction, and the pressure difference between cathode and anode is kept as small as possible. This paper presents a gradient-based extremum seeking control, which controls the inlet oxygen flow for net-power optimization of a PEMFC. High speed, simplicity, and online control decision are the advantages of this controller. Additionally, the paper presents a first order sliding mode controller for decreasing the pressure difference between gases at cathode and anode in order to enhance the PEMFC lifespan. Control law simplicity, not requiring a state observer, and chatter free response are the advantages of the sliding mode controller, which controls the inlet hydrogen flow. Both controllers are simulated on a sample PEMFC model simultaneously, and the results show that the partial pressure difference of oxygen and hydrogen is approximately zero, and at the same time the PEMFC net power is increased up to 17 percent. [ABSTRACT FROM PUBLISHER]

This paper presents the evaluation of a capacitance matrix and the temporal body potential of an artificial orbiting satellite considering a metallic cuboid, parabolic reflector antennas, and solar panels. Integral equations are formed by relating the unknown charge density on the metallic conductor and are solved using the method of moments, in which the pulse functions are used as basis functions and the delta functions are used as testing functions. The surfaces of the conducting structure are meshed using nonuniform triangular subareas. The matrix equations are solved using an iterative generalized minimum residual algorithm. The numerical data on the capacitance matrix and the charge distribution of these structures have been presented. The validity of this analysis has been established by comparing the data on capacitance available in the literature for the metallic cuboid with the data on capacitance computed by the present method for similar structures. The temporal behavior of body potential of the satellite is computed for different cases. [ABSTRACT FROM PUBLISHER]

Transformer windings, as resonant systems, respond to impulse excitation by oscillating voltages and currents. In this paper, a detailed transient circuit analysis of an auto-transformer exposed to a full and a chopped standard lightning impulse has been performed, taking into account each single turn of the two windings. The corresponding inductance and capacitance matrices used in the circuit analysis are obtained by finite-element method (FEM)-calculations. To get the resistances of the turns, eddy currents have to be considered. Since the turns (continuously transposed conductors) consist of a certain number of single strands to keep the eddy current losses low, an appropriate eddy current calculation by FEM has to be performed, taking account of each single strand of the turns. The resulting resistances of the turns are typically several hundred times higher than the respective dc resistances. This has a significant influence on the damping behavior of the high-frequency oscillations of the system. [ABSTRACT FROM AUTHOR]

In this paper, a broadband equivalent node-to-node admittance functions (NAFs) model for shielded power cables are presented aiming at the direct time-domain simulation. The finite-element method is employed to obtain the frequency-dependent per-unit-length resistances, self- and mutual-inductances, and the self- and mutual-capacitances of the power cables. The matrix rational approximations are then applied to obtain the rational model (in pole-residue form) of the terminal admittance matrix of the multi-conductor transmission line (MTL) model. Next, the numerical stability of the rational model is guaranteed by the terminal (port) passivity enforcement technique. The circuit representation of the equivalent NAFs of the full cable with the length of interest can be synthesized based on the pole-residue description. It is validated by comparing the frequency response with the one computed by applying the original MTL model. [ABSTRACT FROM AUTHOR]

A simple and inexpensive method of building a charge meter is discussed and as an application two experiments are suggested. A charge meter can be used for identification and measurement of charges on dielectric media such as teflon, nylon, silk and rubber balloon obtained by method of friction. Teflon and rubber balloon are found to be negatively charged while silk and nylon are found to be positively charged. A charge meter can also be used to measure capacitance of parallel plate capacitors and hence calculate dielectric constant of the medium between its plates. The values of dielectric constant of transparency plastic sheet and plain paper so obtained are 2.71 ± 0.08 and 4.8 ± 0.29. In the last part, the effective capacitance of a capacitor obtained by placing paper and transparency plastic sheet placed one above the other is shown to be equivalent to a series combination of individual paper and transparency plastic sheet capacitors. These experiments can be pedagogical tools for teaching electrostatics. [ABSTRACT FROM AUTHOR]

This paper presents two capacitive comb drive designs for electrostatic actuation of MEMS with the aim to eliminate the levitation effect often observed in such systems. By placing a shield over the comb drive fingers, it is possible to balance the electric field and suppress vertical forces while maintaining the desired lateral motion. By optimizing the comb geometry, we demonstrate that our approach is able to reduce the levitation by an order of magnitude and unwanted coupling of motion from out-of-plane to in-plane by a factor of 7 compared with standard comb architectures fabricated using PolyMUMPs technology, without the need of alternating comb finger polarities or additional control electrodes. Levitation was reduced to 160 nm, for 3.6- \mu \textm lateral displacement at a driving voltage of 80 $V$ . [2016-0156] [ABSTRACT FROM PUBLISHER]

The second part of this paper presents an experimental reliability assessment of microelectromechanical-system bimorph cantilever beams for high-temperature sensing applications. The sensor, presented in Part I, is shown to operate up to 275 ^\circ\C and to have a quality factor of over 5000 at room temperature, a response time of under 600 \mus, and an inherent capacitance uncertainty of under 0.13 fF. In this part, the reliability of the bimorph component of the sensor is tested at sustained high temperatures (up to 275 ^ \circ\C), as well as throughout thermal cycling. The cantilevers are initially thermally annealed to relax the film stresses. During the anneal of the device, there is a decrease in room-temperature tip displacement from 120 to 70 \mu\m and a decrease in the high-temperature tip displacement from 40 to 10 \mu\m. After the thermal anneal, the devices show less than 3 \mu\m of further creep after three months (over 2000 h) at 200 ^\circ \C and over 120 h at 275 ^\circ\C . Over 20 samples have been successfully tested up to 100 million cycles without failure. Record results are demonstrated to over 1.2 billion thermal cycles from fully relaxed to fully deflected states. Consisting of over 1000 beam profile measurements and dozens of individual fabricated chips, this represents one of the largest reliability studies of bimorphs to date.\hfill[2011-0317] [ABSTRACT FROM AUTHOR]

The technology of wireless power transfer has made a great contribution to the quality of life of many people, especially to those relying on implantable devices in the past decades. In order to improve the performance of wireless power transfer systems, a dual-layer nested optimization method using differential evolution (DE) algorithm is proposed in this paper. In contrast to previous methods to derive the compensated capacitance, this proposed method determines the capacitance values using optimization method. By testing a prototype, it is found that the proposed design can have much higher power transfer efficiency when compared to that of traditional method. The dual-layer nested optimization method, based on the design constrains, is also used to determine the parameters of the coils to obtain the maximum power transfer efficiency of the whole system. The result is validated using finite element method (FEM). [ABSTRACT FROM PUBLISHER]

The ordinary orifice transducer widely used in process industries for flow rate measurement produces a differential pressure which is generally measured by a DP cell and thus may suffer from various problems like leakage of process fluid, corrosion of diaphragm materials, etc. In this paper, the design of a noncontact capacitance-type orifice transducer for the measurement of flow rate of a conducting liquid through a pipeline has been described. In the proposed transducer, the use of a diaphragm-type DP cell is not needed, and thus, the problems associated with DP cell are avoided. The theoretical analysis of the flow transducer is presented in this paper. The performance of the flow transducer along with that of the signal conditioner for flow of tap water through a pipeline has been tested experimentally. The experimental results are presented in this paper. A good linearity and repeatability of the sensor capacitance, transducer output, and signal conditioner output with flow rate have been observed. [ABSTRACT FROM PUBLISHER]

A microelectromechanical systems (MEMS) temperature sensor based on a cascade three-stage “bent-beam” structure is described in this paper. A suspended structure mechanically deforms in response to the change in ambient temperature, and then, a displacement is obtained; the structure is composed of three cascaded systems in order to enhance sensor sensitivity. The final conversion is made to an electrical signal that is obtained by using an interdigitated capacitor having one electrode fixed to the substrate and one electrode embedded into the moving tip of the MEMS sensor. The device has been conceived to operate passively in harsh environments where high temperatures could harm active electronic devices. The readout of the unknown temperature is therefore remotely performed by coupling the variable MEMS capacitor to a fixed inductor to compose a resonant LC circuit, which is magnetically coupled to a reader circuit placed outside the environment where the measurement takes place. The temperature to be measured is therefore first converted into a displacement that, in turn, induces a change in a capacitor value; a variation in the resonant frequency of an LC circuit is finally observed through the remote readout circuit. This paper focuses on the analytical and numerical modeling of both the temperature-to-displacement and displacement-to-capacitance conversions, on the design and fabrication of an experimental prototype, on the experimental validation where results are extensively presented and commented, and, finally, on the design of the integrated resonant device for contactless measurements. [ABSTRACT FROM PUBLISHER]

Approximate analytical formulae are presented for calculating the characteristic impedance of elevated coplanar waveguides (CPWs). In such a structure, both the signal and ground traces are suspended above a substrate using airbridge technology. The analysis of this structure is formulated in terms of partial capacitances obtained through conformal mapping techniques. The paper highlights the limitations of previously published formulae. Furthermore, the paper presents a method to overcome these limitations over a limited range of practical geometries. Comparisons between measured, simulated, and calculated results are included, and excellent agreement is obtained for a wide range of geometries. In addition, the effects of CPW-to-elevated coplanar waveguide transitions and supporting posts on the characteristics of elevated lines are analyzed. Good agreement is obtained for a relatively complex fabricated structure which is nonuniform at nine points in the direction of signal propagation. The fabrication of elevated CPW structures is also discussed. [ABSTRACT FROM AUTHOR]

This paper describes how to calibrate four-terminal-pair (4TP) admittance standards using a new short-bar method with a modified Z-matrix expression containing a coefficient C1. The short-bar method is an effective way of measuring of a signal to the standard with better signal-to-noise ratio (S/N) for higher impedance standards, particularly 1 pF. This allows a 1-pF capacitor to be calibrated using direct measurement at frequencies reported for calibrations. As this method does not require the equivalent circuit for interpolation using measurements at frequencies beyond the reported frequencies, it can be applied to 4TP admittance calibration, where the 4TP sections have the same mechanical structure as lower impedance standards. [ABSTRACT FROM AUTHOR]

The paper presents the study of the CuBr laser energy characteristics using capacitively coupled discharge excitation. We have studied the effect of the addition of HBr on laser performance for gas discharge tubes of different bore diameter at various input power conditions. When adding HBr pulse and average output power as well as laser efficiency more than double increase due to the shortening of the current pulse rising time and its duration. The total maximum average lasing power of 3.7 W was obtained at 0.27% efficiency. In the paper, we also notice that when adding admixtures capacitively coupled discharge pumping is superior to traditional glow discharge pumping. [ABSTRACT FROM AUTHOR]

This paper describes the design of the front-end measurement circuit for a miniature electrical capacitance tomography system. This is based on a charge-transfer circuit and is implemented as a custom CMOS integrated circuit that is mounted close to the electrodes to reduce parasitic capacitance. The design has been informed by a 3-D finite-element simulation using the Ansoft Maxwell software. Simulation results suggest that, with averaging, a minimum measurable capacitance change of 100 aF (10-16F) is possible. This paper presents an analytical description of the circuit which, uniquely for such an application, is based on MOSFETs operating in weak inversion. The system has an average sensitivity of 40 mV/fF and can deliver an unprecedented 6250 measurement frames/s. The sensor comprises eight electrodes that are formed on a conical orifice, fabricated using ultrasonic drilling and a minimum diameter of 0.5 mm, through a ceramic substrate. The cross-sectional tomographic images of static objects, which are reconstructed offline, are presented. [ABSTRACT FROM AUTHOR]

This paper presents the careful integration of a newly proposed Z-source topological concept to the basic neutral-point-clamped (NPC) inverter topology for designing a three-level inverter with both voltage-buck and voltage-boost capabilities. The designed Z-source NPC inverter uses two unique X-shaped inductance-capacitance (LC) impedance networks that are connected between two isolated dc input power sources and its inverter circuitry for boosting its ac output voltage. Through the design of an appropriate pulsewidth-modulation (PWM) algorithm, the two impedance networks can be short-circuited sequentially (without shooting through the inverter full dc link) for implementing the ‘nearest-three-vector’ modulation principle with minimized harmonic distortion and device commutations per half carrier cycle while performing voltage boosting. With only a slight modification to the inverter PWM algorithm and by short-circuiting the two LC impedance networks simultaneously, the designed NPC inverter, with no requirement for deadtime delay, can also be operated with a completely eliminated common-mode voltage. Implementation wise, a detailed vectorial analysis interestingly shows that the same generic set of carrier-based modulation expressions can be used for controlling the Z-source two-level inverter and NPC inverter with and without reduced common-mode switching. All findings presented in this paper have been confirmed in simulation and experimentally using an implemented laboratory prototype. [ABSTRACT FROM AUTHOR]

In deep-submicrometer integrated circuits, inductance effects have become increasingly significant, and interconnects are often modeled as transmission lines. An equivalent circuit model, which is called the γd/n model and regularly constructed by two elementary resistance-capacitance-inductance-conductance cells, is proposed for transmission line modeling in this paper. Unlike those moment-matching techniques, the γd/n model is a physical model in nature, and it can be applied to generated high-accuracy, stable, passive, and reduced-order models of transmission lines. In addition, RC(L) interconnect loads are also considered in this paper. Experimental results show that the proposed method can accurately capture the transmission line effect and the capacitive load effect. The waveform obtained by this method differs from that by the exact model in SPICE simulation with the average voltage difference less than 0.9%. For a wide range of interconnect parameters, it has been shown that this method can achieve less than 6% in average error of the 50% delays for both the near-end response and the far-end response. [ABSTRACT FROM AUTHOR]

By applying a fully self-consistent solution of the Schr6dinger-Poisson equations, a simple unified approach has been developed in order to study the gate current and gate capacitance of nanoscale-MOS structures with ultrathin dielectric layer. In this paper, the model has been employed to investigate various gate structure and material combinations, thereby demonstrating wide applicability of the present model in the design of nanoscale-MOSFET devices. The results obtained by applying the proposed model are in good agreement with experimental data and previous models in the literature. A new result concerning optimum nitrogen content in HfSiON high-k gate-dielectric structure reported in this paper requires experimental verification through device fabrication. [ABSTRACT FROM AUTHOR]

In this paper, genetic algorithm-based technique is proposed to estimate and analyze the steady-state performance of a self-excited induction generator (SEIG). The study reveals that the performance of the SEIG is greatly influenced by the operating speed, load, and excitation capacitance. This provides an opportunity for the proper handling of these parameters so as to obtain the required performance characteristics. In this paper, a new technique is proposed to identify these parameters to achieve constant voltage constant frequency operation for SEIG. Theoretical results as obtained have been compared with experimental results and found to be in close agreement. [ABSTRACT FROM AUTHOR]

The lateral insulated gate bipolar transistor (IGBT) behavior differs in many aspects from the well-studied vertical IGBT. In this paper, the voltage derivative during inductive turnoff for a silicon-on-insulator (SOI) lateral IGBT (LIGBT) is analyzed in detail. A complete model which accounts for the voltage rise is implemented through an accurate calculation of the equivalent output capacitance. The model is in excellent agreement with two-dimensional simulations and experimental results across a wide range of conditions. Further, the paper shows that previously: proposed models, which targeted the vertical IGBT, are not adequate for the description of the turnoff voltage rise in the LIGBT. [ABSTRACT FROM AUTHOR]

This paper describes a noncontact capacitive-sensor metrology sensor developed to measure minimum feature sizes, also called critical dimensions, patterned on photomasks that are used in semiconductor device manufacture. Additionally, this paper describes the test structures printed on photomasks that facilitate linewidth metrology with the new sensor. The metrology sensor is fabricated using a low temperature co-fired ceramic technology and its principle is based on noncontact microcapacitance measurements of features on chrome-on-glass reticles. [ABSTRACT FROM AUTHOR]

In a single-phase grid-connected nanogrid system, a bidirectional ac–dc converter is usually required to transfer energy between the ac grid and a dc bus. Active ac power balancing is often implemented to prevent the ac grid ripple power from injecting into the dc bus. A four-phase-leg sinusoidal pulsewidth-modulation (SPWM) converter can readily provide power factor correction and active ac power balancing. In this paper, the use of three-phase-leg SPWM converters for achieving these functions is analyzed. A family of bidirectional single-phase ac–dc three-phase-leg SPWM converters with an ac storage capacitor for use in a nanogrid system is designed with a general control structure and a modulation scheme for minimizing the ac storage capacitance. The general control structure is designed to achieve a decoupled system of a power-factor-correction converter cascaded with an active ac power load at the dc bus. The decoupled system is developed based on decomposition to differential-mode and common-mode voltages. The modulation method involves an extra zero-sequence voltage injection derived from the three-phase-leg SPWM voltages without introducing higher order harmonic distortions. A significant reduction of the ac storage capacitance and an improvement of converter efficiency are achieved. The design and analysis are verified by simulations and experimental measurements. [ABSTRACT FROM AUTHOR]

In this paper, a surface-potential-based compact model is proposed for the capacitance of an AlGaN/GaN high-electron mobility transistor (HEMT) dual field-plate (FP) structure, i.e., with gate and source FPs. FP incorporation in a HEMT gives an improvement in terms of enhanced breakdown voltage, reduced gate leakage, and so on, but it affects the capacitive nature of the device, particularly by bringing into existence in a subthreshold region of operation, a feedback miller capacitance between the gate and the drain, and also a capacitance between the drain and the source, therefore, affecting switching characteristics. Here, we model the bias dependence of the terminal capacitances, wherein the expressions developed for intrinsic charges required for capacitance derivation are analytical and physics-based in nature and valid for all regions of device operation. The proposed model, implemented in Verilog-A, is in excellent agreement with the measured data for different temperatures. [ABSTRACT FROM AUTHOR]

A new type of calculable capacitor was initially built at the National Institute of Metrology, China, in cooperation with the National Measurement Institute, Australia. The capacitor realized the SI unit of capacitance at 1 pF, with an uncertainty of 20 parts in 10^9 . A simplified operational approach was used that avoids the complex substitution measuring process with small-value capacitors. The details of novel aspects of the installation and adjustment processes are presented, together with the experimental results and an initial uncertainty estimation. [ABSTRACT FROM PUBLISHER]

In this paper, an enhancement-mode GaN high-electron mobility transistor (HEMT)-based 7.2-kW single-phase charger was built. Connecting three such single-phase modules to the three-phase grid, respectively, generates a three-phase ∼22-kW charger with the $>{\text{97}}\% $ efficiency and $>{\text{3.3}}-{\rm{kW}/ \rm{L}}$ power density, superior to present Si-device-based chargers. In addition to GaN HEMTs with fast-switching transitions yielding high efficiency, the proposed charger employs the dc/dc stage to control the power factor and power delivery simultaneously, yielding little dc-bus capacitance and thereby high power density. To secure the soft switching for all switches within full voltage and power ranges, a variable switching frequency control with dual phase shifts was adopted at high power, and a triple phase shift was employed to improve the power factor at low power. Both control strategies accommodated the wide input range (80–260 VAC) and output range (200–450 VDC). A closed-loop control for the three-phase charger was realized to minimize the output current ripple and balance the power among three single-phase modules. Experimental results validated this design. [ABSTRACT FROM AUTHOR]

\(A~priori\) evaluations of inductance, stray capacitance, and dc resistance are important aspects in optimizations of inductors. In this paper, analytical formulas of the inductance (self and mutual), dc resistance (solid and litz wires), and the stray capacitances of coaxial inductors were derived for both hexagonal and orthogonal windings. Possible imperfections that occurred during the fabrication process were accounted by the inclusion of axial and azimuth filling factors into the formulations. The formulas presented here were validated using several coaxial coils with rectangular cross sections as reported in the literature and double tested by measurements. Discrepancies between estimated and measured values were less than 1%. The advantage of the present formulation is that optimization efforts are addressed at the earliest stages possible of inductor conception and construction. [ABSTRACT FROM PUBLISHER]

The conventional capacitance-type liquid level sensor consists of an insulated solid metallic rod electrode immersed in the liquid contained in a metallic storage tank, or two such identical electrodes in a nonmetallic storage tank. Such metallic rods may suffer from the self-inductance effect which varies nonlinearly with the level. In this paper, we present a modified capacitance-type level sensor in which effect of self-inductance of the metallic rod has been eliminated. The theoretical equations describing the operation of the sensor are derived. The sensor is designed and tested experimentally and is found to follow the theoretical equations. The experimental results are also presented. A very good linearity of the sensor is observed. [ABSTRACT FROM PUBLISHER]

Abstract: Electro-chemical impedance spectroscopy is widely used to analyze electro-chemical systems. Most attention is paid to the double-layer capacitance and the charge-transfer resistance as they describe the electro-chemical process on the surface of the electrode. Both values can provide specific information about aging mechanisms, which diminish the surface area. This is of interest when capacity tests are restricted to determine the aging. For lead-acid batteries, for example, this is the case in applications like micro-hybrid vehicles or uninterruptible power supply systems. However, the interpretation of impedance spectra of lead-acid batteries necessitates proper measurements, elaborated verification of measurement validity, and a sufficient model of electro-chemical processes. In this work, impedance spectra, recorded on lead-acid test cells, are processed to identify the ohmic resistance, the double-layer capacitance, and the parameters of the charge-transfer reaction of the negative electrode. This electrode suffers from sulfation, a common aging mechanism in current applications. The aim of the paper is to define a correct processing of impedance spectra for lead-acid batteries, and to depict challenges. Furthermore, possible equivalent electrical circuit models for the negative electrode are evaluated regarding their dependencies on state of charge and current rate. Many of these aspects can be transferred to other electro-chemical systems.Graphical Abstract: [ABSTRACT FROM AUTHOR]

The integration of energy storage systems (ESSs) in contemporary applications highly depends on the performance of these devices. Supplying high power for a reasonable period of time is one of their main targets in several applications like backup systems and transport technologies. For this purpose, lithium-ion capacitors (LICs) would demonstrate better suitability than conventional ESSs for applications requiring a small installation space and a long lifetime. They are known for their energy density greater than that of supercapacitors and their power density greater than that of lithium-ion batteries. This paper explains the electrochemical processes that interfere in the storage of energy inside an LIC. The analysis of these phenomena was the tool for assessing the nonlinear capacitance evolution of the LIC with respect to its voltage. Several measurement techniques in the frequency and time domains were elaborated and compared in order to assess this nonlinear behavior of the LIC. Some of the measurement protocols contained constant voltage phases that had a significant effect on the variation of the capacitance. The novelty of this study concerns the introduction of a new measurement protocol that takes into account the particular characteristics of LICs. Their unique behavior is explained for the first time based on a physicochemical analysis. [ABSTRACT FROM PUBLISHER]

With series insulated-gate bipolar transistor (IGBT) operation, well-matched gate drives will not ensure balanced dynamic voltage sharing between the switching devices. Rather, it is IGBT parasitic capacitances, mainly gate-to-collector capacitance Cgc, that dominate transient voltage sharing. As Cgc is collector voltage dependant and is significantly larger during the initial turn-off transition, it dominates IGBT dynamic voltage sharing. This paper presents an active control technique for series-connected IGBTs that allows their dynamic voltage transition dVce/dt to adaptively vary. Both switch ON and OFF transitions are controlled to follow a predefined dVce/dt. Switching losses associated with this technique are minimized by the adaptive dv /dt control technique incorporated into the design. A detailed description of the control circuits is presented in this paper. Experimental results with up to three series devices in a single-ended dc chopper circuit, operating at various low voltage and current levels, are used to illustrate the performance of the proposed technique. [ABSTRACT FROM AUTHOR]