Capacitor Research Papers - Academia.edu (original) (raw)

With adiabatic techniques for capacitor charging, theory suggests that it should be possible to build gates with arbitrarily small energy dissipation. In practice, the complexity of adiabatic approaches has made them impractical. We describe a new CMOS logic family-adiabatic dynamic logic (ADL)-that is the result of combining adiabatic theory with conventional CMOS dynamic logic. ADL gates are simple, general, readily cascadable, and may be fabricated in a standard CMOS process. A chain of 1000 ADL inverters has been constructed in 0.9 pm CMOS and successfully tested at 250 MHz. This result, together with comprehensive circuit simulation, suggest that ADL offers an order of magnitude reduction in power consumption over conventional CMOS circuitry.

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- Logic, Switching, Numerical Simulation, Power Consumption

The Tarmy-Ghausi (TG) active resistor-capacitor (RC) filters using op-amps and its modification by Moschytz are well known to active RC filter designers. These use first-order all-pass networks in a negative feedback loop. New current-mode universal operational transconductance amplifier-capacitor (OTA-C) biquad filters based on the TG active RC filter are considered here. These are based on a recently proposed OTA-C based first-order all-pass network. Three different feedback arrangements are investigated in the proposed filter structure so as to reduce the pole-Q sensitivity. The proposed biquad filters are shown to implement all different types of filters like low-pass, high-pass, band-pass, symmetric notch, all-pass, low-pass notch and high-pass notch. The synthesis of the general biquad is carried out in a novel way by invoking the analogy with direct-form digital filter structures. The special case of all-pass filter realisation derived from the proposed universal filter needs additional hardware for realising the feed-forward coefficients. Hence alternative OTA-C based all-pass filter implementations based on Mitra-Hirano and Gray-Markel second-order digital filter structures are derived in which the coefficients that are used to realise the denominator are shared in the realisation of numerator also. All the proposed circuits are compared with the other structures available in the literature. The simulation results of the proposed circuits are also presented.

- by Diego Caratelli
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- Engineering, Electromagnetism, Electromagnetic Compatibility, RFIC
- by Paulo Delgado
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- Electronic Engineering, Analog Circuits, Electronics, Eletrônica

In the last decades, due to emissions reduction policies, research focused on alternative powertrains among which hybrid electric vehicles (HEVs) powered by fuel cells are becoming an attractive solution. One of the main issues of these vehicles is the energy management in order to improve the overall fuel economy. The present investigation aims at identifying the best hybrid vehicle configuration and control strategy to reduce fuel consumption. The study focuses on a car powered by a fuel cell and equipped with two secondary energy storage devices: batteries and super-capacitors. To model the powertrain behavior an on purpose simulation program called ECoS has been developed in Matlab/Simulink environment. The fuel cell model is based on the Amphlett theory. The battery and the super-capacitor models account for charge/discharge efficiency. The analyzed powertrain is also equipped with an energy regeneration system to recover braking energy. The numerical optimization of vehicle configuration and control strategy of the hybrid electric vehicle has been carried out with a multi objective genetic algorithm. The goal of the optimization is the reduction of hydrogen consumption while sustaining the battery state of charge. By applying the algorithm to different driving cycles, several optimized configurations have been identified and discussed.

- by Arturo de Risi and +1
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- Energy Conversion, Fuel Cell, Energy Management, Optimization

The power consumption of microprocessors is increasing at an alarming rate leading to 2X reduction in the power distribution impedance for every product generation. In the last decade, high I/O ball grid array (BGA) packages have replaced quad flat pack (QFP) packages for lowering the inductance. Similarly, multilayered printed circuit boards loaded with decoupling capacitors are being used to meet the target impedance. With the trend toward system-on-package (SOP) architectures, the power distribution needs can only increase, further reducing the target impedance and increasing the isolation characteristics required. This paper provides an overview on the design of power distribution networks for digital and mixed-signal systems with emphasis on design tools, decoupling, measurements, and emerging technologies.

- by istvan novak
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- Power Systems, Digital Circuits, Power Generation, Printed Circuit Board

Este libro brinda una introducción a la electrónica en semiconductores -también llamada de estado
sólido- para carreras de ingeniería en electrónica, electricidad, computadoras, comunicaciones, control y sistemas. Provee una explicación de los mecanismos de conducción eléctrica en Silicio,
que luego se utiliza para el desarrollo de cuatro dispositivos fundamentales de la electrónica actual: el diodo de juntura, el capacitor Metal-Oxido-Semiconductor (MOS), el transistor MOS, y el transistor bipolar de juntura. El libro conduce al estudiante a que entienda el funcionamiento de cada dispositivo, partiendo de sus principios fundamentales, y que a partir de allí, comprenda en profundidad los diferentes modelos eléctricos que puede utilizar para representarlo, sus alcances y limitaciones. El objetivo último es que el estudiante conozca y sepa utilizar los distintos modelos de los dispositivos electrónicos, de acuerdo al rango de amplitud y frecuencia, para su utilización futura en el diseño y análisis de circuitos.

- by Pedro Julian
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- Argentina, VLSI, Electronica, Ingeniería
- by Anthony Lai
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- Antennas & Radio Wave Propagation, Metamaterials, Composite Materials, Simulation

Shunt capacitor banks are used to improve the quality of the electrical supply and the efficient operation of the power system. Studies show that a flat voltage profile on the system can significantly reduce line losses. Shunt capacitor banks are relatively inexpensive and can be easily installed anywhere on the network. This paper reviews principles of shunt capacitor bank design for substation installation and basic protection techniques. The protection of shunt capacitor bank includes: a) protection against internal bank faults and faults that occur inside the capacitor unit; and, b) protection of the bank against system disturbances.

- by ishara premasiri
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- Electrical Engineering, Capacitor, SCB

Carbon nanostructures-including graphene, fullerenes, etc.-have found applications in a number of areas synergistically with a number of other materials. These multifunctional carbon nanostructures have recently attracted tremendous interest for energy storage applications due to their large aspect ratios, specific surface areas, and electrical conductivity. This succinct review aims to report on the recent advances in energy storage applications involving these multifunctional carbon nanostructures. The advanced design and testing of multifunctional carbon nanostructures for energy storage applicationsspecifically, electrochemical capacitors, lithium ion batteries, and fuel cells-are emphasized with comprehensive examples.

- by Zhanhu Guo
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- Nanomaterials, Nanocomposite, Capacitor, Energy Storage

The dielectric constants (relative permittivities) of water, methanol, ethanol, butanol and acetone were measured at 91.3 kPa and (283.15 and 293.15) K and are reported here. The dielectric constants were determined by using a new setup based on a low-pass filter. The obtained dielectric constant values are compared with those reported in the literature, and are consistent with those reported in the literature. The obtained dielectric constant data were also compared with those calculated by the Kirkwood model. The comparisons indicated that Kirkwood model can be successfully used for calculation of dielectric constants of the pure fluids.

- by hamide amiri
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- Water, Solution Chemistry, Fluid, Models

A 2-D contour integral-equation method for the frequency-domain analysis of arbitrarily shaped power bus structures is presented. The numerically efficient approach allows the rapid and accurate computation of the frequency-dependent transfer parameters between an arbitrary number of ports, as required for embedding the power plane structure into network simulation. A formulation is developed for calculating the voltage distribution between the planes, as well as for determining the resulting radiated fields based on the field-equivalence principle. The method is applied for several test boards including a populated board with a surface-mount decoupling-capacitor network. The suggested approach is well confirmed by an analytical solution for the rectangular structure, by measurement and 3-D full-wave simulation results.

This paper presents a low-dropout regulator (LDO) for portable applications with an impedance-attenuated buffer for driving the pass device. Dynamically-biased shunt feedback is proposed in the buffer to lower its output resistance such that the pole at the gate of the pass device is pushed to high frequencies without dissipating large quiescent current. By employing the current-buffer compensation, only a single pole is realized within the regulation loop unity-gain bandwidth and over 65 phase margin is achieved under the full range of the load current in the LDO. The LDO thus achieves stability without using any low-frequency zero.

- by Raul Perez
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- Power Management, Low Frequency, High Frequency, Capacitor

This paper focuses on the combination of wind turbine (WT), photovoltaic (PV), fuel cell (FC) and ultracapacitor (UC) systems for grid-independent applications. The dynamic behavior of the proposed hybrid system is tested under various wind speed, solar radiation and load demand conditions. The developed model and its control strategy exhibit excellent performance for the simulation of a complete day. In the simulation, the solar radiation and power demand data are based on real world measurements, while the wind speed data are quasi-real because it is simulated based on special wind speed generation algorithms.

- by Mehmet Uzunoglu
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- Engineering, Power System, Modeling, Performance

This paper represents the most effective automatic power factor improvement by using static capacitors which will be controlled by a Microcontroller with very low cost although many existing systems are present which are expensive and difficult to manufacture. In this study, many small rating capacitors are connected in parallel and a reference power factor is set as standard value into the microcontroller IC. Suitable number of static capacitors is automatically connected according to the instruction of the microcontroller to improve the power factor close to unity. Some tricks such as using resistors instead of potential transformer and using one of the most low cost microcontroller IC (ATmega8) which also reduce programming complexity that make it most economical system than any other controlling system. Gl Volume XIII Issue VI Version 29 ( ) Year 013 2 F obal Journal of Researches in Engineering

- by Amedina Ahmed
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- Electrical Engineering, Control Systems Engineering, Control Systems, Capacitor

It is well-known that the high-performance polymeric dielectric films used for high-voltage DC capacitors should have outstanding capabilities in terms of electrical and mechanical properties in order to face harsh operating conditions. Many factors limit the ability of these thin films to face different and growing stresses according to modern electrical requirements. Microstructure properties, additives, impurities, defects formed during manufacturing as well as applied stress types significantly affect the performance of dielectric films and their operational lifetime. This paper presents a comprehensive review of the factors which affect the ageing, degradation and breakdown of metallised polypropylene (PP) capacitors films. The effects of microstructure, surface morphological properties, mechanical properties and defects on the reliability of biaxially oriented polypropylene films (BOPP) are studied. In addition, the phenomena affecting dielectric performance and ageing mechanisms which are induced by electrical, thermal and electrothermal stresses are discussed.

- by Dr. Haider M Umran
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- Materials Science, DIELECTRIC, Capacitor

This paper proposes a method of studying and modcling the dielcctric absorption in capacitors. Because of dielectric absorption, thc voltage on a charged capacitor partially recovers aftcr momentarily shorting its terminals. The magnitude of this voltage recovery depcnds mainly an the dielectric material. Dielcctric absorplian causes errors in some analog applications based on charging and discharging of capacitors, such as samplc-and-hold circuits, integrators and active filters. Designing compensation circuits bawd on models of thc dielectric absorption can reduce these errors. This paper pments an analytical method to build a mathematical model of the diclectric absorption, and an equivalent electrical circuit, The method is based on compartmental analysis theory, mostly used in medicine and biology to study the kinetics of substances in biological systems.

- by Cristina Iorga
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- Kinetics, Systems Biology, Kinetic Theory, Absorption

A wideband LC PLL in 45-nm SOI CMOS technology is presented that has a center frequency of 12.4 GHz and 1.2 octave locking range. The wideband operation is achieved by switching mutual inductances within the inductor coil of the LC oscillator. To minimize resistive switching losses, the inductor coil consists of a non-switchable primary coil and two isolated secondary coils with series switches. When the switches are closed, the overall inductance reduces because of the switched mutual inductances. Three inductor bands, each consisting of 16 switched capacitor sub-bands, span a frequency range from 7.3 to 17.5 GHz. The in-band phase noise measured after a 1/4 divider is better than 107 dBc/Hz at 1 MHz offset frequency in the entire locking range. The PLL is fully differential and its core has a power consumption of 25 mW at the highest oscillation frequency.

- by Thomas Toifl and +1
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- Switching, Oscillator, Q factor, Power Consumption

In this article, double-stacked and triple-stacked metal-insulator-metal (MIM) capacitors fabricated in 0.18 μm CMOS process are reported. These provide high-capacitance density of 2 fF/μm2 and 3.2 fF/μm2 and excellent dc and RF characteristics, respectively. The lumped circuit model of the stacked MIM capacitors is presented for high-frequency applications up to 20 GHz. The stacked MIM capacitors offer a reduced chip area for a given capacitance value and are expected to be a viable choice for integration of RF/mixed-mode circuits in a single chip. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1235–1238, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24305

- by Hyunwon Moon
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- Modeling, Cmos, Capacitor, Optical physics

The wire-bond ball-grid-anay (BGA) package is of interest because of its low cost and high pin counts. For better electrical performance, the coupling in the wire-bond regions needs to be contained. This paper shows a doubleswizzle design that reduces coupling by -40% from a reference single-swizzle design. The smaller coupling was achieved through the proper assignment of ground wires. Test packages with shorted load were built, and the measurements were done by connecting either a vector network analyzer (VNA) or a time-domain reflectometer (TDR) to the balls of the package. The coupled models of bond wires, fanouts, traces, and plating stubs were then extracted from the measured data by a customized extractor. The extracted models gave some insights into the package. The attenuation was larger than expected. Some "spikes" in the measured S11 plots were attributed to the coupling. A package model without coupling would not he able to capture these spikes. Yet there were other spikes that were unexplained. They were finally tracked down to be caused by the Vdd plane and routing. Connecting decoupling capacitors between Vdd and ground balls moved the resonance spikes to higher frequencies.

- by Nirmal Jain
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- Data Mining, Packaging, Routing, Electronic Packaging

Fuzzy logic a b s t r a c t Fuel cell (FC) and ultracapacitor (UC) based hybrid power systems appear to be very promising for satisfying high energy and high power requirements of vehicular applications. The improvement in control strategies enhances dynamic response of the FC/UC hybrid vehicular power system under various load conditions. In this study, FC system and UC bank supply power demand using a current-fed full bridge dc-dc converter and a bidirectional dc-dc converter, respectively. We focus on a novel fuzzy logic control algorithm integrated into the power conditioning unit (PCU) for the hybrid system. The control strategy is capable of determining the desired FC power and keeps the dc voltage around its nominal value by supplying propulsion power and recuperating braking energy. Simulation results obtained using MATLAB Ò & Simulink Ò and ADVISOR Ò are presented to verify the effectiveness of the proposed control algorithm. ª

- by Mehmet Uzunoglu
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- Engineering, Hydrogen, Fuzzy Logic, Power System

This paper compares four commonly used on-wafer calibration methods including multiline thru-reflect-line (TRL), line-reflect-reflect-match, line-reflect-match, and short-open-loadthru, for three diverse coplanar waveguide (CPW) circuits. The magnitudes and phases of 11 and 21 of the CPW circuits are compared to quantify how the specific calibration method influences measured scattering parameters. Special care is taken to ensure that the measured scattering parameters are normalized to the same reference impedance and reference plane for accurate comparison. The measured results are compared with full-wave simulations to provide additional assessment of accuracy. A method to de-embed the discontinuity of the CPW at the probe tip and the CPW of the test structures is presented. The effect of probe-to-device-under-test discontinuity is effectively modeled by one-or two-section of shunt capacitor and series inductor. The results show that the multiline TRL calibration method provides the highest transmission coefficient repeatability on not well-matched circuits and highest accuracy on the three circuits in this paper up to 40 GHz.

- by Kathleen Melde
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- Comparative Study, High Frequency, Manufacturing Engineering, Calibration

Representing a new approach to ultrasound generation and detection, study on piezoelectric micromachined ultrasonic transducers (pMUTs) has been a growing research area in recent years. Intensive research work has been directed on the deposition of lead zirconate titanate (PZT) films on silicon substrates for their excellent piezoelectric coefficients and electromechanical coupling coefficients. However, the high processing temperature required for PZT crystallization results in a low device yield and also makes it difficult to integrate with control circuits. In this paper, a fabrication technology of pMUTs based on piezoelectric P(VDF-TrFE) 70/30 copolymer films has been adopted, with the maximum processing temperature not exceeding 140°C allowing for post-IC compatibility. The entire processing procedures are simple and low cost, as compared with those of capacitive micromachined ultrasonic transducers (cMUTs) and ceramic-based pMUTs. The applications of the fabricated pMUTs as airborne ultrasonic transducers and transducer arrays have been demonstrated. Reasonably good device performances and high device yield have been achieved.

- by Skandar Basrour and +3
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- Engineering, Electrochemistry, Computer Aided Design, Titanium

While numerous organic molecules have promising oxidation potentials and theoretical energy densities for use as redox capacitor cathode materials, practical application requires that the molecules remain in contact with the electrode during cycling. In this report, a hybrid molecule was synthesized and electrochemically polymerized to prepare a conducting polymer backbone of poly(3,4-ethylenedioxythiophene) with pendant thioether functionalities as redox (and charge-storing) sites. The choice of an electron deficient aromatic solvent was critical to form a conducting polymer film from the hybrid monomer, as well as to achieve stable charge/discharge cycling of the pendant-type polymer. In nitrobenzene, 86% of the charge was retained after 100 charge/discharge cycles.

- by Jay Henderson
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- Engineering, Electrochemistry, Conducting Polymers, Conducting Polymer

In this paper, the problems encountered in system voltages for a fast growing utility, i.e. the Ministry of Electricity and Water of the Sultanate of Oman in the Arabian Gulf are discussed. The utility has mostly air-conditioning load in the summer and the system encountered voltage stability problems during peak summer conditions. The paper presents a detailed discussion on recommendations proposed to remedy the voltage problems. The most critical period for voltage problems during summer days and its effect on remote load buses in terms of voltage profile is discussed. System wide weak voltage buses have been identified.

- by Atif Khan
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- Electric Power Systems, Air Conditioning, Utility, Voltage Stability

A 14-bit analog-to-digital converter (ADC) design for GSM/GPRS/EDGE handsets is implemented in 0.25 m CMOS. The measured SNR/SNDR/DR is 85.2/84.1/88 dB respectively. The modulator and the clock generator consume 1.05 mA from 2.7 V supply. A delay-locked-loop (DLL)-based bias scheme is implemented to guarantee that amplifier slewing takes a fixed percentage of the clock cycle over process corners, temperature, and clock frequency. The proposed biasing scheme is shown to minimize settling error variations and contain design margins.

- by Nikolaus Klemmer
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- Switching, Noise, Clock, Capacitor

a iqbalfauzi@s.itb.ac.id, b arcana@chem.itb.ac.id, c deana@chem.itb.ac.id (corresponding authors) Abstract. Batteries are being developed to solve the global energy crisis. Using portable electronic devices, especially mobile phones and notebook computers, has been increasing, and leading to a strong need of their power-sources. However, secondary batteries using a liquid electrolyte have weaknesses, such as prone to leakage and difficulty of packing. Solid polymer electrolyte is a solution to the existing problems. The objective of this research is to prepare an environmentalfriendly and cheap material as the solid polymer electrolyte. In the present study, the effect of succinyl group on to polymer electrolyte membrane which synthesized from chitosan and lithium perchlorate salts was investigated. The N-succinyl chitosan was obtained by reacting chitosan with succinic anhydride. Solid polymer electrolyte membranes were derived from N-succinyl chitosan with different ratios of lithium perchlorate. The degree of deacetylation of chitosan was determined by FTIR analysis. The degree of deacetylation and molecular mass (M v ) of chitosan were 79.26% and 691,053 g/mol, respectively. Synthesis of N-succinyl chitosan has been successfully carried out, which is indicated by the characteristic peaks at wavenumbers of 1640 cm -1 and 1560 cm -1 correspond to -C=O stretching and -NH bending of succinyl groups on FTIR spectrum of Nsuccinyl chitosan. Modification of chitosan by the addition of succinyl group increases the membrane ionic conductivity values. Chitosan membrane conductivity is 2.88×10 -6 S.cm -1 , while the conductivity after adding succinyl groups was increased to 3.93×10 -4 S.cm -1 . A N-succinyl chitosan membrane contained 10% (w/w) lithium perchlorate showed conductivity of 8.01×10 -3 S.cm -1 . This solid polymer electrolyte membrane was suggested to have one potential used for polymer electrolyte in lithium battery applications.

- by Deana Wahyuningrum and +1
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- Engineering, Advanced Materials, Physical sciences, PEO

- by Qiling Zhang
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- Electrical Engineering, Capacitor, SCB

Multilevel inverters (MLIs) with switchedcapacitor (SC) units have been a widely rehearsed research topic in power electronics since the last decade. Inductorless/transformerless operation with voltage boosting feature, and inherent capacitor self-voltage balancing performance with a reduced electro magnetic interference make the SC-MLIs an attractive converter over the other available counterparts for various applications. There have been many developed SC-MLIs structures recently put forward, where different basic switching techniques are used to generate multiple (discrete) output voltage levels. In general, the priority of the topological development is motivated by the number of output voltage levels, overall voltage gain, and full dc-link voltage utilization, while reducing the component counts and stress on devices for better efficiency and power density. To facilitate the direction of future research in SC-MLIs, this article presents a comprehensive review, critical analysis, and categorization of the existing topologies. Common fundamental units are generalised and summarised with their merits and demerits. Ultimately, major challenges and research directions are outlined leading to the future technology road-map for more practical applications.

- by Mojtaba Forouzesh
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- Computer Science, Power Electronics, Capacitor, Voltage

Different types of commercially available electrochemical double layer capacitors (EDLCs) were analysed in accelerated ageing tests by impedance spectroscopy. From these measurements the parameters of an impedance model were determined.... more

- by Julia Kowal
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- Engineering, Operations Strategy, Performance, Impedance Spectroscopy

This paper proposes a control strategy of open winding permanent magnet synchronous motor (OW PMSM) in field weakening modes. There are two inverters. One of them connected to the traction battery. Main bridge inverter aimed to provide power with approximately unity power factor, another one to capacitor. Floating bridge inverter aimed to control capacitor voltage on desired value and provide reactive power to the moto. Compare OW PMSM control system with conventional field-oriented control (FOC) shows that proposed method helps to reach speed 1.41 times more than FOC system. FOC system was simulated with 310V DC power supply. OW PMSM with 160V DC power supply and 500 nanofarad capacitor.

- by IAEME Publication
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- Matlab, Motor, Permanent Magnets, Capacitor

As is known, undesired simultaneous switching noise produced by high-speed digital integrated circuits (ICs) and power vias may propagate along parallel-plane structures of multilayer printed circuit boards (PCBs) and IC packages, which act as parallel-plane cavity resonators. To minimize effects of the parallelplane cavities, we need to minimize the impedance profile of a PCB power bus in the frequency range of interest. We can minimize the impedance profile by reducing power bus plane spacings, and by using local and global decoupling techniques that employ decoupling capacitors. But, in the gigahertz-range, discrete capacitors are not efficient due to the parasitic inductance of their connections to the power bus. In this paper, in addition to the analysis of cavity-mode resonances in multilayered PCBs, we derived expressions for the impedance envelope that can be used for predicting the impedance profile of a power bus. This theoretical approach and the derived envelope expressions are confirmed analytically by the cavity-model method, by a full-wave field solver, and by laboratory measurements carried out by a network analyzer.

This paper investigates voltage and reactive power control in radial and closed loop distribution systems and how the presence of distributed generation (DG) affects the control. Comparative analysis between voltage and reactive power... more

- by Ferry Viawan
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- Distributed System, Control Systems, Comparative Analysis, Capacitor

Today, ultracapacitors are a viable component for production aim designs in the power electronics world. The need for highly reliable back-up and emergency power are creating significant markets for energy storage and power delivery. Electrical wind turbine pitch systems, uninterruptible power supplies and electronic products such as wireless communication devices and digital cameras are some of the many applications where ultracapacitors have been designed in. Ultracapacitors are components which have properties of a complexe capacitor system which is sensitive to voltage, temperature and frequency. The understanding of their behavior is primordial to characterize and operate them.

- by Dr Debmalya Bhattacharya
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- Engineering, Capacitor, Energy Storage, Supercapacitor

RF MEMS technology can offer enhanced performance over the conventional solid-state devices. Along with other RF MEMS components, antennas have been investigated. This paper presents a unique review and survey of RF MEMS antennas. Here, antennas can be categorized into (i) generic antennas and (ii) antenna circuits. The former employs some forms of mechanical actuation for movements of the radiation elements. With the latter, individual radiation elements are physically stationary and integrated with RF MEMS switches and/or variable capacitors to alter their electrical length and diversity. In addition, (iii) antenna subsystems incorporating RF MEMS tuneable circuits and beam forming networks should not be overlooked. Examples of these antenna categories are described and conclusions drawn.

- by S. Lucyszyn
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- Antennas, Antenna arrays, Radio Frequency, Capacitor
- by Junlong Yao
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- Engineering, Morphology, Polymer Blends, Dielectric Properties

This paper reports a high-sensitivity low-noise capacitive accelerometer system with one micro-g Hz resolution. The accelerometer and interface electronics together operate as a second-order electromechanical sigma-delta modulator. A detailed noise analysis of electromechanical sigma-delta capacitive accelerometers with a final goal of achieving subg resolution is also presented. The analysis and test results have shown that amplifier thermal and sensor charging reference voltage noises are dominant in open-loop mode of operation. For closed-loop mode of operation, mass-residual motion is the dominant noise source at low sampling frequencies. By increasing the sampling frequency, both open-loop and closed-loop overall noise can be reduced significantly. The interface circuit has more than 120 dB dynamic range and can resolve better than 10 aF. The complete module operates from a single 5-V supply and has a measured sensitivity of 960 mV/g with a noise floor of 1.08 g Hz in open-loop. This system can resolve better than 10 g Hz in closed-loop.

- by Navid Yazdi
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- Switching, Noise reduction, Si, Accelerometers

A novel automatic test pattern generator (ATPG) for stuck-at faults of asynchronous sequential digital circuits is presented. The developed ATPG does not require support by any design-for-testability method nor external software tool. The shortest test sequence generation is guaranteed by breadth-first search. The contribution is unique hazard identification before the test generation process, state justification on the gate level, sequential fault propagation based on breadth-first search and stepwise composition of state graphs for sequential test generation. A new six-valued logic together with a new algorithm was developed for hazardous transition identification. The internal combinational ATPG allows to generate test patterns one by one and only if it is required by sequential test generation. The developed and implemented ATPG was tested with speed-independent and quasi-delay-insensitive benchmark circuits.

- by dinesh kumar sharma
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- Microelectronics, Power Electronics, Digital Circuits, Algorithm

Data from the ITRS2003 roadmap for 2010 predicts voltages for microprocessors in hand-held electronics will decrease to 0.8 V with current and power increasing to 4 A and 3 W, respectively. Consequently, low power converters will move to multimegahertz frequencies with a resulting reduction in capacitor and inductor values by factors of 5 and 20, respectively. Values required at 10 MHz, for a low power buck converter, are estimated at 130 nH and 0.6 uF, compatible with the integration of magnetics onto silicon and the concept of power supply-on-chip (PSOC). A review of magnetics-on-silicon shows that inductance values of 20 to 40 nH/mm 2 can be achieved for winding resistances less than 1 . A 1-H inductance can be achieved at 5 MHz with dc resistance of 1 and a Q of four. Thin film magnetic materials, compatible with semiconductor processing, offer power loss density that is lower than ferrite by a factor of 5 at 10 MHz. Other data reported includes, lowest dc resistance values of 120 m for an inductance of 120 nH; highest Q of 15 for an inductance of 350 nH and a current of 1 A for a 1-H inductor. Future technology challenges include reducing losses using high resistivity, laminated magnetic materials, and increasing current carrying capability using high aspect-ratio, electroplated copper conductors. Compatible technologies are available in the power switch, control, and packaging space. Integrated capacitor technology is still a long-term challenge with maximum reported values of 400 nF/cm 2 .

- by Cian O Mathuna
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- Power Electronics, Magnetic Materials, Space Technology, Ferrite

ZnO-based varistors protect electronic circuits against overvoltage. High temperature from the range of 1150-1300°C is required for proper sintering of such material. Varistor inks with lower firing temperature are needed for application in thick-film and LTCC technology. ZnO-based thick-film composition was prepared and varistors were fabricated on alumina and LTCC substrate. Different topologies (capacitorlike or planar), electrode metallurgies (PdAg, Au or Pt-based) and firing profiles (850°C or 950°C) were used. Samples microstructure was investigated. Varistor I-V characteristics, long-term stability and durability to high voltage pulses were examined. Satisfactory results were achieved, because nonlinearity coefficient a up to 23 was obtained for capacitor-like varistors with Pt terminations on LTCC substrates, long-term thermally aged (150 h at 250°C) varistors had slightly smaller nonlinearity coefficient and characteristic voltage, V 1 mA and components subjected to series of high voltage pulse (1000 pulses with 10 mA amplitude and 5 ms duration each) exhibited almost the same electrical parameters.

- by Andrzej Dziedzic
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- Microstructure, High Voltage, Reliability, Durability

In compact pulsed power conditioning systems, a high electric energy density of its capacitors is of interest. Commercially available capacitors are normally designed for long storage time and long lifetime. The performance of capacitors in terms of energy density capability can be improved by overstress or overcharge, that is, charging to a significantly higher energy density than specified. This paper explores the limits of overstressing commercially available capacitors for short time spans. The selected capacitors have a nominal dc voltage in the range of 2.5-10 kV and a capacitance in the range of 0.015-0.12 /spl mu/F. Two different storage times have been considered: 2 /spl mu/s and 20 ms. A high-voltage test setup was constructed. For the short storage time, it was possible to overstress the energy density as compared to nominal values with a factor of 26 and for the long storage time with a factor of 14 for the best performing capacitor. Other capacitors behaved significantly poorer, especially for the long storage time.

- by Jan Isberg
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- Design, Pulsed Power, High Voltage Engineering, High Voltage

This paper proposes a coordinated control method for an under-load tap changer (ULTC) with switching capacitors in distribution systems to reduce the operation numbers of both devices. The proposed method consists of two stages. In the first stage, the dispatch schedule of capacitors is determined using a genetic algorithm with forecasted loads to reduce the power loss and to improve the voltage profile during a day. In the second stage, each capacitor operates according to this dispatch schedule and the ULTC is controlled in real time with the modified reference voltages considering the dispatch schedule of the capacitors. Simulation results show that the proposed method performs better than a conventional control method.

- by Jong-young Park
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- Power Systems, Optimal Control, Genetic Algorithms, Distributed System

Evidence is provided that a class of materials with dielectric constants greater than 10 5 , herein called super dielectric materials (SDM), can be generated readily from common, inexpensive materials. Specifically it is demonstrated that high surface area alumina powders, loaded to the incipient wetness point with a solution of boric acid dissolved in water, have dielectric constants greater than 4*10 8 in all cases, a remarkable increase over the best dielectric constants previously measured, ca. 1*10 4 . It is postulated that any porous, electrically insulating material (e.g. high surface area powders of silica, titania), filled with a liquid containing a high concentration of ionic species will potentially be an SDM. Capacitors created with the first generated SDM dielectrics (alumina with boric acid solution), herein called New Paradigm Super (NPS) capacitors display typical electrostatic capacitive behavior, such as increasing capacitance with decreasing thickness, and can be cycled, but are limited to a maximum effective operating voltage of about 0.8 V. A simple theory is presented: Water containing relative high concentrations of dissolved ions saturates all, or virtually all, the pores (average diameter 500 Å) of the alumina. In an applied field the positive ionic species migrate to the cathode end, and the negative ions to the anode end of each drop. This creates giant dipoles with high charge, hence leading to high dielectric constant behavior. At about 0.8 volts, water begins to break down, creating enough ionic species to 'short' the individual water droplets. Potentially NPS capacitor stacks can surpass 'supercapacitors' in volumetric energy density.

- by Jonathan Phillips
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- Engineering, Energy, Materials, DIELECTRIC

Due to the rising demand for low-power portable battery-operated electronic devices, there is an increasing need for low-voltage low-power low-drop-out (LDO) regulators. This provides motivation for research on high-gain wide-bandwidth amplifiers driving large capacitive loads. These amplifiers serve as error amplifiers in low-voltage LDO regulators. Two low-power efficient three-stage amplifier topologies suitable for large capacitive load applications are introduced here: single Miller capacitor compensation (SMC) and single Miller capacitor feedforward compensation (SMFFC). Using a single Miller compensation capacitor in three-stage amplifiers can significantly reduce the total capacitor value, and therefore, the overall area of the amplifiers without influencing their stability. Pole-splitting and feedforward techniques are effectively combined to achieve better small-signal and large-signal performances. The 0.5-m CMOS amplifiers, SMC, and SMFFC driving a 25-k//120-pF load achieve 4.6-MHz and 9-MHz gain-bandwidth product, respectively, each dissipates less than 0.42 mW of power with a 1-V power supply, and each occupies less than 0.02 mm 2 of silicon area.

- by Alfio Dario Grasso
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- Stability, Sliding mode control, Frequency, Low Power

The necessity of the converters compactness in many applications imposes the reduction of their different components size when it is possible. In this paper, a control method allowing the use of a small size dc-link capacitor for the cascade of voltage controlled-rectifier/inverter-motor drive system is proposed. This is achieved by adding the power balance equation in the system's model and the application of an exact input/output feedback linearization technique in a way that the rectifier controller compensates any sudden change in the inverter load, which is here an induction motor. Since the exact input/output feedback linearization technique is sensitive to the uncertainties over system parameters, a robust control strategy based on sliding mode controller is proposed. By this approach, the dc-link voltage becomes almost insensitive to the load variations. As a result, the level of the dc-link voltage could be stabilized with a small size dc-link capacitor. Without any considerations of the RMS current stress on this dc-link capacitor, a calculation method of a minimum value of this capacitor based on its storage energy is proposed. All the investigations are shown by computer simulations and the performance of controlled system is verified by experimentation results.

- by PISIT LIUTANAKUL
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- Performance, Robust control, Energy Conversion, Nonlinear Control

A new architecture for improvement of slew rate (SR) of an op-amp or an operational transconductance amplifier (OTA) in FinFET technology is proposed. The principle of operation of the proposed architecture is based on a set of additional current sources which are switched on, only when OTA should provide a high current, usually for charge or discharge of large load capacitor. Therefore, the power overhead is less compared to conventional high SR designs. The commonly used two-stage Miller-compensated op-amp, designed and optimized in sub 45 nm FinFET technology with 1 V single supply voltage, is used as an example for demonstration of the proposed method. For the same FinFET technology and with optimal design, it is shown that the slew rate of the op-amp is significantly improved. The slew rate is improved from 273 to 5590V/μs for an input signal with a rise time of 100 ps. The other performance measures such as gain and phase margin remain unchanged with the additional circuitry u...

This study describes the design of a multiphase sinusoidal oscillator (MSO) based on log-domain filtering concept. The circuit is a direct realisation of a first-order differential equation for obtaining the inverting and non-inverting low-pass filters. Each low-pass filter comprises only a grounded capacitor and four transistors. The proposed MSO can be instantaneously controlled over a very wide frequency range by controlling the current for the oscillation frequency and oscillation condition which indicates the proposed MSO's suitability in high-frequency applications. A validated bipolar junction transistor (BJT) model is used in SPICE simulation operated from a single power supply as low as 2.5 V. The oscillation frequency is controlled over four decades of frequency. The total harmonic distortions for three phase (11.5 MHz) and four phase (7 MHz) are, respectively, obtained around 2.4 and 2.2% which enables them to be fully integrated in telecommunication systems. The power consumption is around 5.5 mW for 100 mA bias current. Moreover, experimental results of three-phase MSO are included.

- by Pipat Prommee
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- Power Electronics, High Frequency, First-Order Logic, Telecommunication Systems

We report on the fabrication and electrical characterization of MIM capacitors using as dielectric a thin porous anodic alumina layer between two Al films. The Al 2 O 3 /Al stack is grown electrochemically by partly anodizing an Al film on Si, while a top Al film is then deposited on the aluminum oxide and patterned in order to define the capacitor area. The obtained MIM capacitors exhibit at the same time large capacitance density (above ∼5 fF/μm 2 ), low leakage current density (below ∼10 −9 A/cm 2 at 2 V), and good thermal stability of operation, demonstrated by an α coefficient that changes by less than 10% for temperature changes of the order of 100 K. The temperature stability is further demonstrated by the low leakage current density (below ∼7 × 10 −9 A/cm 2 ) even at temperatures as high as 420 K.