Showing papers on "Equivalent series resistance published in 2006"

Improvement of efficiency of dye-sensitized solar cells based on analysis of equivalent circuit

Abstract: The present paper discusses the principle of dye-sensitized solar cells (DSCs) in terms of a new physics-based equivalent circuit model. This model is proposed following analysis by electrochemical impedance spectroscopy of the voltage dependence of the internal resistance elements of DSCs. The influence of these elements upon cell performance in areas such as short circuit current density (JSC), open circuit voltage (VOC) and fill factor (FF) was examined based on the equivalent circuit. It was demonstrated that the haze factor of TiO2 electrodes is a useful index when fabricating light-confined TiO2 electrodes to improve JSC, and that blocking the TiO2 surface with molecules is an effective way of reducing interfacial charge recombination at the TiO2 surface and of improving shunt resistance and VOC. FF was also improved by reduction of the internal series resistance, which is composed of the following three elements: the redox reaction resistance at the platinum counter electrode, the resistance of carrier transport by ions in the electrolyte, and resistance due to the sheet resistance of the transparent conducting oxide. Finally, the highest efficiency scores of 10.4% and 10.8% (aperture illumination area 1.004 cm2 and 0.2227 cm2, respectively) were confirmed by a public test center.

Electrode surface treatment and electrochemical impedance spectroscopy study on carbon/carbon supercapacitors

Abstract: Power improvement in supercapacitors is mainly related to lowering the internal impedance The real part of the impedance at a given frequency is called ESR (equivalent series resistance) Several contributions are included in the ESR: the electrolyte resistance (including the separator), the active material resistance (with both ionic and electronic parts) and the active material/current collector interface resistance The first two contributions have been intensively described and studied by many authors The first part of this paper is focused on the use of surface treatments as a way to decrease the active material/current collector impedance Al current collector foils have been treated following a two-step procedure: electrochemical etching and sol-gel coating by a highly-covering, conducting carbonaceous material It aims to increase the Al foil/active material surface contact leading to lower resistance In a second part, carbon-carbon supercapacitor impedance is discussed in term of complex capacitance and complex power from electrochemical impedance spectroscopy data This representation permits extraction of a relaxation time constant that provides important information on supercapacitor behaviour The influence of carbon nanotubes addition on electrochemical performance of carbon/carbon supercapacitors has also been studied by electrochemical impedance spectroscopy

Temperature dependent characteristics of λ∼3.8μm room-temperature continuous-wave quantum-cascade lasers

Abstract: Temperature dependent characteristics of λ∼3.8μm quantum-cascade lasers (QCLs) operating up to 318K in continuous-wave (cw) mode are reported. A high-reflectivity coated 11.5-μm-wide and 4-mm-long epilayer-down bonded QCL using a diamond submount shows a considerable improved cw operation with an output power of 143mW and a threshold current density of 1.51kA∕cm2 at 298K. The temperature dependence on optical and electrical performances of the QCLs with respect to the output power, slope efficiency, threshold current/voltage, turn-on voltage, differential series resistance, and emission wavelength are investigated systematically above liquid nitrogen temperature.

Process for the production of electrolyte capacitors of high nominal voltage

Abstract: The invention relates to a process for the production of electrolyte capacitors having a low equivalent series resistance and low residual current for high nominal voltages, electrolyte capacitors produced by this process and the use of such electrolyte capacitors.

Electrolyte capacitors having a polymeric outer layer and process for their production

Abstract: The invention relates to a process for the production of electrolyte capacitors having a low equivalent series resistance and low residual current, and which comprise a solid electrolyte of conductive polymers and an outer layer comprising conductive polymers applied in the form of a dispersion. Electrolyte capacitors produced by this process and the use of such electrolyte capacitors are also provided.

Determining Components of Series Resistance from Measurements on a Finished Cell

Abstract: Detailed expressions are given for computing the components of series resistance for a cell with a common contact pattern of parallel, equally-spaced gridlines which are perpendicular to two or more busbars. Front busbars and gridlines, contact resistance, emitter sheet, substrate, back metal and back busbars are all considered. No detailed thickness profiles are needed for any feature, only basic lengths and separations along with four-point resistance measurements. Results are given for a two-bus 15 cm square multicrystalline silicon cell having an efficiency of 15.0%. The total series resistance is 1.04 Omega-cm2, dominated by the gridline contribution. The addition of a third busbar is calculated to result in an increase in FF of 0.018, corresponding to an increase of 0.36% in absolute efficiency. A method for providing a coarse map of pseudo contact resistance for a finished cell, using only a four-point probe, is also introduced

A method for dynamic system characterization using hydraulic series resistance

Abstract: The pressure required to drive flow through a microfluidic device is an important characteristic of that device. We present a method to measure the flow rate through microfluidic components and systems, including micropumps and microvalves. The measurement platform is composed of two pressure sensors and a glass tube, which provides series resistance. The principle of the measurement is the fluid dynamical equivalent of Ohm's law, which defines the relationship between current, resistance, and voltage that are analogues to flow rate, hydraulic resistance, and pressure drop, respectively. Once the series resistance is known, it is possible to compute the flow rate through a device based on pressure alone. In addition, the dynamic system characteristics of the device-resistance and capacitance-can be computed. The benefits of this method are its simple configuration, capability of measuring flow rate accurately from the more easily measured pressure, and the ability to predict the dynamic response of microfluidic devices.

Process for the production of electrolyte capacitors

Abstract: The invention relates to a process for the production of electrolyte capacitors having a low equivalent series resistance and low residual current, electrolyte capacitors produced by this process and the use of such electrolyte capacitors.

Electrolytic capacitors with a polymeric outer layer and process for the production thereof

Abstract: The invention relates to a process for the production of electrolytic capacitors with low equivalent series resistance and low residual current consisting of a solid electrolyte made of conductive polymers and an outer layer containing conductive polymers, to electrolytic capacitors produced by this process and to the use of such electrolytic capacitors.

Fully depleted extremely thin SOI technology fabricated by a novel integration scheme featuring implant-free, zero-silicon-loss, and faceted raised source/drain

Abstract: A new integration scheme is presented to solve device and manufacturing issues for extremely thin SOI (ETSOI) technology with high-k/metal gate. Source/drain and extensions are effectively doped by an implant-free process to successfully reduce series resistance below 200 Omegaldrm. A zero-silicon-loss process is developed to eliminate loss of thin SOI layer during gate and spacer processes, enabling structural demonstration of sub-2 nm ETSOI. Even without strain boosters, a remarkable PFET drive current of 550 muA/mum is achieved at Ioff = 3nA/mum, VDD = 0.9 V with 6 nm SOI channel and 25 nm physical gate length. Shortchannel effects are well-controlled with DIBL less than 100 mV/V and subthreshold swing less than 90 mV/dec. A 15% reduction in parasitic capacitance is achieved by a faceted raised source/drain (RSD). Excellent electrostatics and small device dimensions render ETSOI devices suitable for 22-nm node and beyond.

Compact Models Based on Transmission-Line Concept for Integrated Capacitors and Inductors

Abstract: This paper presents a compact modeling methodology for inductors and capacitors based on transmission-line theory. Using continued fractions approximation, second- and third-order intrinsic inductor and capacitor models are demonstrated. With the second-order model, one can accurately predict inductor and capacitor behavior up to their first resonance frequencies. With the third-order model, one can match the measured inductor or capacitor response beyond the first resonance frequency. Wideband accurate passive models developed here are essential for transient and harmonic-balance analysis where out-of-band frequencies are important. The model parameters are extracted directly from S-parameter measurement without a need for optimization. Furthermore, the frequency-dependent nonlinear effects of spiral inductors and metal-insulator-metal capacitors are expressed based on simple models without resorting to frequency-dependent parameters

Method and apparatus to provide compensation for parasitic inductance of multiple capacitors

Abstract: A coupled winding cancels parasitic inductance of first and second capacitors. In an EMI filter having common mode capacitors and a differential capacitors, first and second windings cancel parasitic inductance of the common mode and differential capacitors.

Inductor winding capacitance cancellation using mutual capacitance concept for noise reduction application

Abstract: In this paper, the properties of mutual capacitance between two capacitors are first discussed. It is found that the effects of mutual capacitance can be represented by two positive or negative capacitors across the two capacitors. These two equivalent capacitors can be used to cancel the parasitic capacitance of inductors. Because the mutual capacitance can be emulated using two small capacitors, the proposed method can easily be implemented in practical components. The prototypes are then built and the cancellation is verified using a network analyzer. Further EMI measurements in a practical power circuit prove that there is a significant improvement in the inductor's filtering performance.

Modification of Al Current Collector/Active Material Interface for Power Improvement of Electrochemical Capacitor Electrodes

Abstract: This paper presents results about carbon nanofibers (CNFs) synthesis and their use as surface treatments for Al current collector for carbon electrochemical capacitors in organic electrolyte. CNFs have been successfully synthesized on a pretreated Al substrate; the pretreatment of Al consists of an etching followed by a carbonaceous sol-gel deposit. Performances of cells assembled with pretreated Al and pretreated Al coated by CNFs have been compared by using galvanostatic cycling measurements. Internal resistances as low as 0.4 Omega cm2 are obtained for cells using CNF-treated Al. The increase of the surface contact and interface conductivity between the Al and the active material are responsible for this internal resistance decrease. The capacitance obtained for the two cells is the same (95 F g–1 of activated carbon). Performances [both equivalent series resistance (ESR) and capacitance] are stable over 10 000 cycles, proving the great efficiency of surface treatments.

A compact equivalent circuit for the dark current-voltage characteristics of nonideal solar cells

Abstract: This paper presents a compact electrical equivalent circuit which describes the dark current-voltage characteristics of nonideal p-n junction solar cells in a wide range of temperatures. The model clearly separates the voltage drop in the junction and bulk regions. It is based on the combination of two exponential mechanisms, shunt and series resistances and space-charge limited current. In order to increase the accuracy of the parameter extraction process, both ln(I-V) and its derivative plots are fitted simultaneously. From the temperature dependence of the extracted parameters, the conduction mechanisms governing the I-V characteristics can be obtained without assuming dominating terms. In addition, the extracted parameters can be related to other electrical magnitudes obtained from such independent measurements as capacitance-voltage measurements (diffusion potential) and illuminated current-voltage characteristics (series resistance and open-circuit voltage). To exemplify the application, a p+ a-SiC:...

Magnetically differential inductors and associated methods

Abstract: A method and apparatus is provided for use in an integrated circuit (60) or printed circuit board for reducing or minimizing interference. An inductance is formed using two or more inductors (10A, 10B) coupled together and configured such that current flows through the inductors (10A, 10B) in different directions, thus at least partially canceling magnetic fields. When designing a circuit, the configuration of the inductors(10A, 10B), as well as the relative positions of portions of the circuit, can be tweaked to provide optimal interference or noise control.

Cancellation of capacitor parasitic parameters for noise reduction application

Abstract: In this paper, a method is proposed to reduce the equivalent series inductance and equivalent series resistance of capacitors. The method is, first, theoretically analyzed and then verified through experiments. This method will show that it can be used for both film capacitors and electrolytic capacitors, greatly improving the performance of both. Applications in practical power converters prove that the proposed technique can significantly reduce high frequency (HF) electromagnetic interference noise. The technique can also be very useful to reduce HF voltage ripple.

Mathematical Model of Heterogeneous Electrochemical Capacitors and Calculation of Their Parameters

Abstract: A mathematical model of heterogeneous electrochemical supercapacitors (HES) is proposed which makes it possible to develop capacitors with optimal designs and make calculations of their energy, capacity, and power parameters. Special attention is paid to the processes which occur in electrodes with double electric layer (DEL) of HES capacitors during their charge and discharge by different currents. It is demonstrated theoretically that in the efficiency of HES capacitors' operation, an important role is played by distribution of the potential along the thickness of electrodes with DEL. In order to build capacitors with improved parameters and optimal design, it is of paramount importance to take account of the type and value of conductivity of the material of the electrode with DEL and conductivity of the electrolyte in its pores. Analysis is performed to determine the efficiency of PbO 2 |H 2 SO 4 |C system capacitors' operation subject to thickness, conductivity, and specific capacitance of the electrode with DEL. It is established that energy and capacity parameters of the capacitors depend to a great extent on conductivity of their negative electrodes and electrolytes. It is demonstrated that there are different mechanisms of losses of energy and charge of the capacitors during their charge, discharge, and storage.

A New On-Chip Substrate-Coupled Inductor Model Implemented With Scalable Expressions

Abstract: Accurate modeling of the on-chip inductor is essential for the design of high-speed, low-power, and low-noise radio-frequency integrated circuits. The conventional model has a measurable discrepancy as the current flowing in the substrate is not correctly considered. The substrate-coupled inductor model, however, considers the losses generated in both the vertical and horizontal directions. This model gives an intelligent explanation of the reduction in equivalent resistance between terminals with increasing frequency as well as the inductance and quality factor (Q-factor). In order to implement a fully scalable model, the circuit elements in the substrate-coupled inductor model are expressed as monomial equations in terms of physical geometry. These equations consider the physical implications of the parameters as well as employing a mathematical fit for extrapolation. Measurements are made on inductors fabricated using a standard 0.35-mum CMOS process and a 0.15-mum silicon-on-insulator CMOS process to successfully verify this model.

A noise optimization formulation for CMOS low-noise amplifiers with on-chip low-Q inductors

Abstract: A noise optimization formulation for a CMOS low-noise amplifier (LNA) with on-chip low-Q inductors is presented, which incorporates the series resistances of the on-chip low-Q inductors into the noise optimization procedure explicitly. A 10-GHz LNA is designed and implemented in a standard mixed-signal/RF bulk 0.18-/spl mu/m CMOS technology based on this formulation. The measurement results, with a power gain of 11.25 dB and a noise figure (NF) of 2.9 dB, show the lowest NF among the LNAs using bulk 0.18-/spl mu/m CMOS at this frequency.

A comparative study of BSF layers for GaAs-based single-junction or multijunction concentrator solar cells

Abstract: An effective back surface field is a key structural element for a high-efficiency GaAs concentrator solar cell, either in a multijunction or in a single-junction device. In this paper, several BSF materials are analysed, namely: (1) p++GaAs(Zn), (2) p+Ga0.5In0.5P(Zn) and (3) p++Al0.2Ga0.8As(C). The results of the comparison demonstrate that the best option is C-doped Al0.2Ga0.8As, which exhibits a low series resistance and behaves as an excellent minority carrier mirror; p++GaAs(Zn) shows reduced minority carrier mirror properties resulting from Zn diffusion and p+Ga0.5In0.5P(Zn) is shown to produce important series resistance problems because of an unfavourable heterojunction with GaAs.