Showing papers on "Capacitor published in 2002"

Adaptive piezoelectric energy harvesting circuit for wireless remote power supply

Abstract: This paper describes an approach to harvesting electrical energy from a mechanically excited piezoelectric element. A vibrating piezoelectric device differs from a typical electrical power source in that it has a capacitive rather than inductive source impedance, and may be driven by mechanical vibrations of varying amplitude. An analytical expression for the optimal power flow from a rectified piezoelectric device is derived, and an "energy harvesting" circuit is proposed which can achieve this optimal power flow. The harvesting circuit consists of an AC-DC rectifier with an output capacitor, an electrochemical battery, and a switch-mode DC-DC converter that controls the energy flow into the battery. An adaptive control technique for the DC-DC converter is used to continuously implement the optimal power transfer theory and maximize the power stored by the battery. Experimental results reveal that use of the adaptive DC-DC converter increases power transfer by over 400% as compared to when the DC-DC converter is not used.

Multi-stage switched capacitor DC-DC converter

Abstract: A three-stage switched capacitor DC-DC converter capable of generating an output boosted voltage in increments of less than power supply voltage. A first stage of the DC-DC converter comprises two capacitors and three switches, which alternate a connection of the two capacitors. The two capacitors are connected in series when charging by turning one of the switches ON, and are connected in parallel when discharging by turning the other two of the switches ON.

Effects of floating-gate interference on NAND flash memory cell operation

Abstract: Introduced the concept of floating-gate interference in flash memory cells for the first time The floating-gate interference causes V/sub T/ shift of a cell proportional to the V/sub T/ change of the adjacent cells It results from capacitive coupling via parasitic capacitors around the floating gate The coupling ratio defined in the previous works should be modified to include the floating-gate interference In a 012-/spl mu/m design-rule NAND flash cell, the floating-gate interference corresponds to about 02 V shift in multilevel cell operation Furthermore, the adjacent word-line voltages affect the programming speed via parasitic capacitors

Status quo and future prospects for metallized polypropylene energy storage capacitors

Abstract: The most important polymer film used in commercial capacitors is biaxially oriented polypropylene. Other materials, such as polyester or paper, are also used for selfhealing metallized capacitors, depending on the application. Capacitors manufactured with polypropylene have the big advantage of being less expensive than other materials, and have a very low equivalent series resistance (ESR), due to the propylene-repeating group, which results in a regular polymer chain. Electrical breakdown behavior will be analyzed in order to improve the electric field stress. Performance versus energy density will be investigated as well. We will give an overview of new proposals in the field of films, considering their reported better dielectric and mechanical performance.

Grid current regulation of a three-phase voltage source inverter with an LCL input filter

Abstract: Many grid connected power electronic systems, such as STATCOMs, UPFCs and distributed generation system interfaces, use a voltage source inverter (VSI) connected to the supply network through a filter. This filter, typically a series inductance, acts to reduce the switching harmonics entering the distribution network. An alternative filter is a LCL network, which can achieve reduced levels of harmonic distortion at lower switching frequencies and with less inductance, and therefore has potential benefits for higher power applications. However, systems incorporating LCL filters require more complex control strategies and are not commonly presented in literature. This paper proposes a robust strategy for regulating the grid current entering a distribution network from a three-phase VSI system connected via an LCL filter. The strategy integrates an outer loop grid current regulator with inner capacitor current regulation to stabilise the system. A synchronous frame PI current regulation strategy is used for the outer grid current control loop. Linear analysis, simulation and experimental results are used to verify the stability of the control algorithm across a range of operating conditions. Finally, expressions for "harmonic impedance" of the system are derived to study the effects of supply voltage distortion on the harmonic performance of the system.

Interfacial Chemistries for Nanoscale Transfer Printing

Abstract: We describe a patterning technique that uses self-assembled monolayers and other surface chemistries for guiding the transfer of material from relief features on a stamp to a substrate. This purely additive contact printing technique is capable of nanometer resolution. Pattern transfer is fast and it occurs at ambient conditions. We illustrate the versatility of this method by printing single-layer metal patterns with feature sizes from a few tens of microns to a few tens of nanometers. We also demonstrate its use for patterning, in a single step, metal/dielectric/metal multilayers for functional thin film capacitors on plastic substrates.

Charge balance control schemes for cascade multilevel converter in hybrid electric vehicles

Abstract: This paper presents transformerless multilevel converters as an application for high-power hybrid electric vehicle (HEV) motor drives. Multilevel converters: (1) can generate near-sinusoidal voltages with only fundamental frequency switching; (2) have almost no electromagnetic interference or common-mode voltage; and (3) make an HEV more accessible/safer and open wiring possible for most of an HEV's power system. The cascade inverter is a natural fit for large automotive hybrid electric drives because it uses several levels of DC voltage sources, which would be available from batteries, ultracapacitors, or fuel cells. Simulation and experimental results show how to operate this converter in order to maintain equal charge/discharge rates from the DC sources (batteries, capacitors, or fuel cells) in an HEV.

Novel polymer–ceramic nanocomposite based on high dielectric constant epoxy formula for embedded capacitor application

Abstract: Embedded capacitor technology can increase silicon packing efficiency, improve electrical performance, and reduce assembly cost compared with traditional discrete capacitor technology. Developing a suitable material that satisfies electrical, reliability, and processing requirements is one of the major challenges of incorporating capacitors into a printed wiring board (PWB). Polymer–ceramic composites have been of great interest as embedded capacitor material because they combine the processability of polymers with the high dielectric constant of ceramics. A novel nanostructure polymer–ceramic composite with a very high dielectric constant (er ∼110, a new record for the highest reported er value of a nanocomposite) was developed in this work. A high dielectric constant is obtained by increasing the dielectric constant of the epoxy matrix (er >6) and using the combination of lead magnesium niobate–lead titanate (PMN–PT)/BaTiO3 as the ceramic filler. This nanocomposite has a low curing temperature (<200°C); thus, it is multichip-module laminate (MCM-L) process-compatible. An embedded capacitor prototype with a capacitance density of 50 nF/cm2 was manufactured using this nanocomposite and spin-coating technology. The effect of the composite microstructure on the effective dielectric constant was studied. This novel nanocomposite can be used for integral capacitors in PWBs. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1084–1090, 2002

Diode-clamped multilevel converters: a practicable way to balance DC-link voltages

Abstract: The converter topologies identified as diode-clamped multilevel (DCM) or, equivalently, as multipoint clamped (MPC), are rarely used in industrial applications, owing to some serious drawbacks involving mainly the stacked bank of capacitors that constitutes their multilevel DC link. The balance of the capacitor voltages is not possible in all operating conditions when the MPC converter possesses a passive front end. On the other hand, in AC/DC/AC power conversion, the back-to-back connection of a multilevel rectifier with a multilevel inverter allows the balance of the DC-link capacitor voltages and, at the same time, it offers the power-factor-correction capability at the mains AC input. An effective balancing strategy suitable for MPC conversion systems with any number of DC-link capacitors is presented here. The strategy has been carefully studied to optimize the converter efficiency. The simulation results related to a high-power conversion system (up to 10 MW) characterized by four intermediate DC-link capacitors are shown.

Wireless micromachined ceramic pressure sensor for high-temperature applications

Abstract: In high-temperature applications, such as pressure sensing in turbine engines and compressors, high-temperature materials and data retrieval methods are required. The microelectronics packaging infrastructure provides high-temperature ceramic materials, fabrication tools, and well-developed processing techniques that have the potential for applicability in high-temperature sensing. Based on this infrastructure, a completely passive ceramic pressure sensor that uses a wireless telemetry scheme has been developed. The passive nature of the telemetry removes the need for electronics, power supplies, or contacts to withstand the high-temperature environment. The sensor contains a passive LC resonator comprised of a movable diaphragm capacitor and a fixed inductor, thereby causing the sensor resonant frequency to be pressure-dependent. Data is retrieved with an external loop antenna. The sensor has been fabricated and characterized and was compared with an electromechanical model. It was operated up to 400/spl deg/C in a pressure range from 0 to 7 Bar. The average sensitivity and accuracy of three typical sensors are: -141 kHz Bar/sup -1/ and 24 mbar, respectively.

Germanium MOS capacitors incorporating ultrathin high-/spl kappa/ gate dielectric

Abstract: For the first time, we have successfully demonstrated the feasibility of integrating a high-permittivity (/spl kappa/) gate dielectric material zirconium oxide into the MOS capacitors fabricated on pure germanium substrates. The entire fabrication process was essentially performed at room temperature with the exception of a 410/spl deg/C forming gas anneal. After processing steps intended to remove the germanium native oxide interlayer between the zirconium oxide dielectric and germanium substrate, an excellent capacitance-based equivalent SiO/sub 2/ thickness (EOT) on the order of 5-8 /spl Aring/ and capacitance-voltage (C-V) characteristics with hysteresis of 16 mV have been achieved. Additionally, excellent device yield and uniformity were possible using this low thermal budget process.

Flying capacitor multilevel inverters and DTC motor drive applications

Abstract: In this paper, the requirements imposed by a direct torque control (DTC) strategy on multilevel inverters are analyzed. A control strategy is proposed in order to fulfill those requirements when a flying-capacitor multilevel inverter is used. Simulation and practical results will confirm the performance of the proposed strategy when using the multilevel inverter to control an induction motor by the DTC principle. Also, the advantages of using a multilevel inverter with a DTC strategy are shown by simulation results.

Current rectification circuit for voltage source inverters with separate energy stores replaces phase blocks with energy storing capacitors

Abstract: A current rectification circuit comprising single- or multi-phase voltage source inverters has switchable energy stores comprising unipolar capacitors which can take up energy during overvoltage conditions and prevent short circuits and other uncontrolled energy emission. A current rectification circuit comprising single- or multi-phase voltage source converters has phase blocks replaced by connection-compatible tripolar units comprising switchable internal energy stores in the form of unipolar capacitors so that energy is taken up during overvoltage conditions and uncontrolled energy emissions, especially short circuits, are prevented and a given capacitance between the P and N terminals and the energy content of the substitute units can be established. An Independent claim is also included for a process for controlling the circuit above.

High density chip carrier with integrated passive devices

Abstract: A carrier for a semiconductor component is provided having passive components integrated in its substrate. The passive components include decoupling components, such as capacitors and resistors. A set of connections is integrated to provide a close electrical proximity to the supported components.

Use of KCl Aqueous Electrolyte for 2 V Manganese Oxide/Activated Carbon Hybrid Capacitor

Abstract: This study reports a hybrid capacitor in neutral KCI aqueous electrolyte, which consists of amorphous manganese oxide (a-MnO 2 .nH 2 O) as a cathode and activated carbon as an anode. The electrochemical performance of the hybrid capacitor is characterized by cyclic voltammetry and a dc charge/discharge test. The hybrid capacitor shows ideal capacitor behavior with an extended operating voltage of 2 V. The extended operating voltage is preferentially attributed to having asymmetric electrodes with different stable voltage windows and good electrochemical stability in neutral KCl aqueous electrolyte. According to the extended operating voltage, the energy density of the hybrid capacitor at a current density of 0.25 A/g, was found to be 28.8 Wh/kg which is comparable to that of an amorphous ruthenium oxide capacitor (26.7 Wh/kg). The hybrid capacitor also shows no degradation of capacitance during 100 cycles except an initial loss of 7% within a few cycles.

A capacitor-less 1T-DRAM cell

Abstract: A simple true 1 transistor dynamic random access memory (DRAM) cell concept is proposed for the first time, using the body charging of partially-depleted SOI devices to store the logic "1" or "0" binary states. This cell is two times smaller in area than the conventional 8F/sup 2/ 1T/1C DRAM cell and the process of its manufacturing does not require the storage capacitor fabrication steps. This concept will allow the manufacture of simple low cost DRAM and embedded DRAM chips for 100 and sub-100 nm generations.

Capacity limits and matching properties of integrated capacitors

Abstract: Theoretical limits for the capacitance density of integrated capacitors with combined lateral and vertical field components are derived. These limits are used to investigate the efficiency of various capacitive structures such as lateral flux and quasifractal capacitors. This study leads to two new capacitor structures with high lateral-field efficiencies. These new capacitors demonstrate larger capacities, superior matching properties, tighter tolerances, and higher self-resonance frequencies than the standard horizontal parallel plate and previously reported lateral-field capacitors, while maintaining comparable quality factors. These superior qualities are verified by simulation and experimental results.

Driving circuit for current control element and image display device

Abstract: PROBLEM TO BE SOLVED: To eliminate the influence of variance in the threshold characteristic of a driving transistor. SOLUTION: The disclosed driving circuit for the current control element has the driving transistor 6 and current control element 7 which are connected in series between a power line 1 and a ground line 2, a hold capacitor 5 which is connected between the connection point between the driving transistor 6 and current control element 7 and the gate electrode of the driving transistor 6, and a select gate transistor 4 which is connected between a signal line 3 and the gate electrode of the driving transistor 6. Then the driving circuit turns on the select gate transistor 4 in a selection period to input a 1st signal voltage from the signal line 3, inputs and holds a 2nd signal voltage from the signal line 3 in the hold capacitor 5 after discharging signal charges written to the hold capacitor 5 through the driving transistor 6, and turns off the select gate transistor 4 in a non-selection period to supply a current to the current control element 7 through the driving transistor 6. COPYRIGHT: (C)2003,JPO

Electric double-layer capacitor

Abstract: PROBLEM TO BE SOLVED: To provide an electric double-layer capacitor using a polarizing electrode which will not block the polymerization reaction of a polymer electrolyte, in an electric double-layer capacitor with high safety which uses the polymer electrolyte. SOLUTION: In an electric double-layer capacitor, polarizing electrodes containing an active carbon species are disposed opposite to each other via a polymer electrolyte. The electric double-layer capacitor includes a polymer obtained by reacting a piperazine derivative, in which the pH of the active carbon species is in the range of 4 to 9, and the polymer electrolyte is represented by Formula (A) (refer to Chemical Formula 1), a hydrosilylated compound represented by Formula (B) (refer to Chemical Formula 2, and a compound represented by Formula (D). COPYRIGHT: (C)2003,JPO

Switching frequency imposition and ripple reduction in DTC drives by using a multilevel converter

Abstract: A new strategy for direct torque control with imposed switching frequency (DiCoIF) is proposed. This strategy was specially designed to operate with a multicell (flying capacitors) inverter with any number of levels, which means it can also be used for standard two-level inverters. This approach combines the well known advantages of the multicell. inverter with those of a direct torque controlled (DTC) based strategy. It is shown that the multicell topology presents enough degrees of freedom to control both torque and flux with very low ripple and high dynamics on one hand, and to impose the switching frequency and the capacitors voltage balance on the other hand. Experimental and simulation results, obtained with a standard two-level inverter and with a four-level multicell inverter, are presented and discussed. Finally, a comparative analysis either with the classical DTC and field oriented techniques is carried out.

Tunable barium strontium titanate thin film capacitors for RF and microwave applications

Abstract: The measurement results for thin film barium strontium titanate (BST) based voltage tunable capacitors intended for RF applications are reported. At 9 V DC, BST capacitors fabricated using MOCVD (metalorganic chemical vapor deposition) method achieved 71% (3.4:1) tunability. The measured device quality factor (Q) for BST varactors is comparable with the device Q for commercially available varactor diodes of similar capacitance. The typical dielectric loss tangent was in the range 0.003-0.009 at VHF. Large signal measurement and modeling results for BST thin film capacitors are also presented.

Multicell converters: active control and observation of flying-capacitor voltages

Abstract: The multicell converters introduced more than ten years ago make it possible to distribute the voltage constraints among series-connected switches and to improve the output waveforms (increased number of levels and apparent frequency). The balance of the constraints requires an appropriate distribution of the flying voltages. This paper presents some solutions for the active control of the voltages across the flying capacitors in the presence of rapid variation of the input voltage. The latter part of this paper is dedicated to the observation of these voltages using an original modeling of the converter.

5-GHz CMOS wireless LANs

Abstract: This paper first provides an overview of some recently ratified wireless local-area network (WLAN) standards before describing an illustrative 5-GHz WLAN receiver implementation. The receiver, built in a standard 0.25-/spl mu/m CMOS logic technology, exploits several recent developments, including lateral-flux capacitors, accumulation-mode varactors, injection-locked frequency dividers, and an image-reject low-noise amplifier. The receiver readily complies with the performance requirements of both IEEE 802.11a and ETSI HiperLAN. It exhibits a 7.2-dB noise figure, as well as an input-referred third-order intercept and 1-dB compression point of -7 and -18 dBm, respectively. Image rejection for this double conversion receiver exceeds 50 dB throughout the frequency band without using external filters. Leakage out of the RF port from the local oscillators is under -87 dBm, and all synthesizer spurs are below the -70-dBm noise floor of the instrumentation used to measure them. The receiver consumes 59 mW from a 1.8-V supply and occupies only 4 mm/sup 2/ of die area, in no small measure due to the use of fractal capacitors for ac coupling.

Charge-pump circuits: power-consumption optimization

Abstract: In this paper, an optimized strategy for designing charge pumps with minimum power consumption is presented. The approach allows designers to define the number of stages that, for a given input, and an output voltage, maximize power efficiency. Capacitor value is then set to provide the current capability required. This approach was analytically developed and validated through simulations and experimental measurements on 0.35-/spl mu/m EEPROM CMOS technology. This approach was then compared with one which minimized the silicon area and it was shown that only a small increase in area is needed to minimize power consumption.

High-frequency chip packages

Abstract: A packaged semiconductor chip includes features such as a chip carrier having a large thermal conductor which can be solder-bonded to a circuit board so as to provide enhanced thermal conductivity to the circuit board and electromagnetic shielding and a conductive enclosure which partially or completely surrounds the packaged chip to provide additional heat dissipation and shielding. The packaged unit may include both an active semiconductor chip and a passive element, desirably in the form of a chip, which includes resistors and capacitors. Inductors may be provided in whole or in part on the chip carrier. A module includes two circuits and an enclosure with a medial wall between the circuits to provide electromagnetic shielding between the circuits.

A new matrix converter motor (MCM) for industry applications

Abstract: The trend in electrical drives is to integrate the frequency converter, the electrical motor, and even the gear or the pump into a single unit, in order to reduce the costs, to increase the overall efficiency and the equipment reliability. This paper presents the first integrated regenerative frequency converter motor for industry applications, based on a matrix converter topology. The low volume, the sinusoidal input current, the bidirectional power flow, and the lack of the bulky and limited-lifetime electrolytic capacitors recommend this topology for this application. This paper shows how the matrix converter disadvantages-the lack of bidirectional power devices, the lower voltage transfer ratio, and the overvoltages caused by the input filter during power-up-that have delayed the industrial implementation have been overcome. In order to demonstrate the validity of the solution, a 4-kW matrix converter motor prototype is built using a standard frequency converter motor enclosure for testing the requirements for an industrial drive. The tests demonstrate the good performance of the drive.

Non-optical signal isolator

Abstract: A non-optical isolator having a driver circuit for providing an input signal to one or more first passive components which are coupled across a galvanic isolation barrier to one or more corresponding second passive components, and an output circuit that converts the signal from the second passive components to an output signal corresponding to the input signal. The entire structure may be formed monolithically as an integrated circuit on one or two die substrates, for low cost, small size, and low power consumption. The passive components may be coils (140, 142) or capacitor plates (130, 132, 134, 136), for example. When the first and second passive components are capacitor plates, a Faraday shield (51) may be provided between them, with the first and second passive components being referenced to separate grounds and the Faraday shield (51) referenced to the same ground as the second passive components.