Showing papers on "Filter capacitor published in 1998"

A high-efficiency CMOS voltage doubler

Abstract: A charge pump cell is used to make a voltage doubler using improved serial switches. A complete power efficiency theory is presented which fits the measurements. The importance of capacitors is shown with plots of power efficiency versus load and stray capacitors. Several problems arising at low voltage or high frequency are developed and some optimizations are presented. The substrate current is totally suppressed by the technique of bulk commutation. A power efficiency of 95% has been reached using external capacitors. A fully integrated charge pump is also presented and shows a maximum power efficiency of 75%.

Failure prediction of electrolytic capacitors during operation of a switchmode power supply

Abstract: Electrolytic filter capacitors are frequently responsible for static converter breakdowns. To predict these faults, a new method to set a predictive maintenance is presented and tested on two types of converters. The best indicator of fault of the output filter capacitors is the increase of ESR (equivalent series resistance). The output-voltage ripple /spl Delta/V/sub o/ of the converter increases with respect to ESR. In order to avoid errors due to load variations, /spl Delta/V/sub o/ is filtered at the switching frequency of the converter. The problem is that this filtered component is not only dependent on the aging of the capacitors, but also on the ambient temperature, output current, and input voltage of the converter. Thus, to predict the failure of the capacitors, this component is processed with these parameters and the remaining time before failure is deduced. Software was developed to establish predictive maintenance of the converter. The method developed is as follows. First, a reference system including all the converter parameters was built for the converter at its sound state, i.e., using sound electrolytic filter capacitors. Then, all these parameters were processed and compared on line to the reference system, thereby, the lifetime of these capacitors was computed.

Micromachined electro-mechanically tunable capacitors and their applications to RF IC's

Abstract: Micromachined electro-mechanically tunable capacitors with two and three parallel plates are presented. Experimental devices have been fabricated using a standard polysilicon surface micromachining process. The two-plate tunable capacitor has a measured nominal capacitance of 2.05 pF, a Q-factor of 20 at 1 GHz, and achieves a tuning range of 1.5:1, The three-plate version has a nominal capacitance of 4.0 pF, a Q-factor of 15.4 at 1 GHz, and a tuning range of 1.87:1. The tuning ranges achieved here are near theoretical limits. Effects due to various physical phenomena such as temperature, gravity, and shock are examined in detail. An RF voltage-controlled oscillator with an integrated inductor and a micromachined tunable capacitor is also demonstrated. The active circuit and the inductor have been fabricated in a 0.5 /spl mu/m CMOS process. The voltage-controlled oscillator has been assembled by bonding together the CMOS and the micromachined parts. The 1.35 GHz voltage-controlled oscillator has a phase noise of -98.5 dBc/Hz at a 100 kHz offset from the carrier.

Chip capacitors and chip capacitor electromagnetic interference filters

Abstract: An electromagnetic interference (EMI) filter capacitor assembly is provided for shielding and decoupling a conductive terminal pin or lead of the type used, for example, in an implantable medical device against passage of external interference signals. The EMI filter is constructed of relatively inexpensive ceramic chip capacitors which replace relatively expensive feedthrough capacitors as found in the prior art. The chip capacitors are mounted directly onto a hermetic feedthrough terminal in groups of two or more which vary in physical size, dielectric material and capacitance value so that they self-resonate at different frequencies. This "staggering" of resonant frequencies and direct installation at the hermetic terminal provides the EMI filter with sufficient broadband frequency attenuation. In one preferred form, multiple chip capacitor groupings are mounted onto a common base structure, with each capacitor grouping associated with a respective terminal pin. In another preferred form, a non-conductive substrate is provided with metalized circuit traces to better accommodate the mounting of the chip capacitors. Additionally, novel chip capacitor geometry/termination-metallization is provided which significantly reduces the internal inductance of the capacitor to improve its high frequency performance as an EMI filter. Such reduced inductance chip capacitor designs are readily adaptable to incorporate multiple electrically isolated active plate sets within a single monolithic casing.

Chip capacitor electromagnetic interference filter

Abstract: An electromagnetic interference (EMI) filter capacitor assembly is provided for shielding and decoupling a conductive terminal pin or lead of the type used, for example, in an implantable medical device against passage of external interference signals. The EMI filter is constructed of relatively inexpensive ceramic chip capacitors which replace relatively expensive feedthrough capacitors as found in the prior art. The chip capacitors are mounted directly onto a hermetic feedthrough terminal in groups of two or more which vary in physical size, dielectric material and capacitance value so that they self-resonate at different frequencies. This "staggering" of resonant frequencies and direct installation at the hermetic terminal provides the EMI filter with sufficient broadband frequency attenuation. In one preferred form, multiple chip capacitor groupings are mounted onto a common base structure, with each capacitor grouping associated with a respective terminal pin. In another preferred form, a non-conductive substrate is provided with metalized circuit traces to better accommodate the mounting of the chip capacitors. Additionally, novel chip capacitor geometry/termination-metallization is provided which significantly reduces the internal inductance of the capacitor to improve its high frequency performance as an EMI filter.

Investigation and mitigation of harmonic amplification problems caused by single-tuned filters

Abstract: This paper investigates the harmonic amplification problems in a plastics plant and the appropriate mitigation methods. Four single-tuned filters (LC filters) were installed to eliminate the harmonic currents from three 6-pulse rectifiers. However, after the capacitance reduction of some filter capacitors, the driving point impedance at the frequency of 8th order harmonic increased severely and the harmonic current of this order was amplified. There were many failures of the power filter capacitors. Field measurements and computer simulations are used to verify the disturbance problems. Finally, two high-pass damped filters are recommended to replace the original single-tuned filters. The amplification problems at some even-order harmonics can be avoided.

Investigation of candidate VRM topologies for future microprocessors [voltage regulator modules]

Abstract: Future generation microprocessors are expected to exhibit much heavier loads and much faster transient slew rates. Today's voltage regulator module (VRM) will need a large amount of extra decoupling and output filter capacitors to meet future requirements, which basically makes the existing VRM topologies impractical. In this paper, a candidate topology, interleaved quasi-square wave, is proposed. Its design, simulation and experimental results are presented.

ESR and ESL of ceramic capacitor applied to decoupling applications

Abstract: Power distribution system noise affects computer product timing performance, signal integrity and electromagnetic interference. Between 1 MHz and 1 GHz, the primary means of reducing power distribution noise is with ceramic decoupling capacitors. To achieve a certain target impedance, it is important to characterize the ESR of ceramic decoupling capacitors, as this directly determines the number of capacitors required on a board. A new technique to extract ESR is described in this paper. Another factor which determines the capacitance value of decoupling capacitors is the ESL (equivalent series inductance) associated with capacitors mounted on a PCB. A study that compares the ESL of different pad layout geometries is also presented.

Ultra-small capacitor array

Abstract: An electronic device has a plurality of capacitors in an ultra-small integrated package. The device has a plurality of terminal structures on one terminal side of the package to permit inverted mounting to a printed circuit board. The terminals are widely spaced, with the individual capacitors being located entirely in between. The device is produced on a suitable substrate using thin film manufacturing techniques. A lead-based dielectric having a high dielectric constant is preferably utilized for each capacitor to provide a relatively high-capacitance value in a relatively small plate area.

Evaluation of capacitors at cryogenic temperatures for space applications

Abstract: Advanced electronic systems designed for use in planetary exploration missions must operate efficiently and reliably under the extreme low temperatures of deep space environment. In addition, spacecraft power electronics capable of low temperature operation will greatly simplify the thermal management system by eliminating the need for heating units and associated equipment and thereby reduce the size and weight of the overall power system. In this study, film, mica, solid tantalum and electric double layer capacitors were evaluated as a function of temperature in terms of their dielectric properties. These properties included capacitance stability and dielectric loss in the frequency range of 50 Hz to 100 kHz. DC leakage current measurements were also performed on the capacitors. The results obtained are discussed and conclusions are made concerning the suitability of the capacitors investigated for low temperature applications.

Calorimetric apparatus for measurement of power losses in capacitors

Abstract: A calorimetric apparatus has been designed especially for measurement of losses in capacitors. The original feature of this determination of capacitor losses lies in the use of the isothermal calorimetry and in the measurement of an electrical power and not of a temperature rise. The accuracy of the method is very good and is independent of the value of the capacitor dissipation factor, it is very useful for capacitors with very low losses. The Equivalent Series Resistance of polymer film capacitors, using polypropylene, polycarbonate, and polyethylene terephtalate, have been determined under rated voltage, in the rang 1 kHz-1 MHz, between 220 K and 370 K. The losses in the dielectric material have been separated from the losses in the metallic parts and their variations with temperature and frequency have been studied. Unlike electrical devices, the calorimetric apparatus allows us to carry out measurements of power losses in capacitors used for power electronic application (filtering, decoupling), under non-sinusoidal applied voltages.

Electrolytic or film capacitors

Abstract: Over the last eight years, significant improvements have been made in the field of polypropylene capacitors. Thinner films and more sophisticated metallization techniques have allowed the range of operating voltages to be lowered to some hundreds of volts. The upper voltage area of the electrolytic capacitors is now covered by the polymer film capacitors. This overlapping is examined through a comparison of the main electrical criteria.

New tantalum capacitors in power supply applications

Abstract: Capacitors used in various applications are usually selected for the usage by the type of capacitor. This selection process is most visible in the selection of the aluminum electrolytic for power supply applications. Developments related to improve performance of an alternative type of capacitor is sometimes lost to the user because of the narrow focus given to the one type It is of the designer's best interest to be aware of the developments of all types for all applications. This paper presents the latest developments for power applications with the tantalum capacitor.

About the DC-link capacitors voltage balance in multi-point clamped converters

Abstract: The multi-point clamped converter (MPCC) represents an interesting technical solution to overcome the limitations in voltage and power posed by the existing semiconductor devices. However, if real power must be delivered to the load, DC-link capacitors exhibit a problematic voltage unbalance, that can be faced in both active or passive ways, that is, by using or not using additional components. Both approaches can be used together, in order to optimize the system performances. The authors have analyzed this problem from an analytical point of view and have developed a modulation control strategy that exploits the inherent redundancy in switching configurations to achieve a correct voltage sharing, in the case of a MPCC with four DC-link capacitors. The results obtained are presented and discussed in a critical way and they are correlated to the case where an active rectifier is used as an input stage to achieve near unity power factor and capacitors voltage balance.

Composite high frequency parts and mobile communication unit using them

Abstract: PROBLEM TO BE SOLVED: To obtain a composite high frequency parts by which can insertion loss is reduced and the circuit is made small and to obtain a mobile communication unit using them. SOLUTION: The composite high frequency parts 10 comprise a diplexer 11, 1st and 2nd high frequency switches 12, 13, and 1st and 2nd filters 14, 15. Then the diplexer 11 comprises 1st inductors L11, L12, and 1st capacitors C11-C15. The 1st high frequency switch 12 comprises 1st diodes D11-D13, 2nd inductors L21-L25, and 2nd capacitors C21-C25. Moreover, the 2nd high frequency switch 13 comprises 1st diodes D21, D22, 3rd inductors L31-L33, and 3rd capacitors C31-C33. Furthermore, the 1st filter 14 comprises a 4th inductor L41, and 4th capacitors C41, C42. Then the 2nd filter 15 comprises a 5th inductor L51 capacitors C51, C52. COPYRIGHT: (C)2000,JPO

Power supply unit with built-in electric double-layer capacitor

Abstract: PROBLEM TO BE SOLVED: To provide a power supply unit with built-in electric double-layer capacitors wherein the safeties to their overchargings and dischargings are considered thoughtfully and their instantaneous charging or discharging currents are made large. SOLUTION: A voltage sensing portion 11 senses the voltage applied across positive and negative terminals 5A, 5B of electric double-layer capacitors 1 connected in series with each other. The voltage applied across the terminals 5A, 5B or the electric double-layer capacitors 1 is increased when the capacitors 1 are charged excessively. A voltage comparing portion 19 decides whether the voltage applied across the terminals 5A, 5B exceeds an upper limit voltage or not. In the meantime, the voltage applied across the terminals 5A, 5B of the electric double-layer capacitors 1 is decreased when the capacitors 1 are discharged excessively. A voltage comparing portion 15 decides whether the voltage applied across the terminals 5A, 5B drops beyond a lower limit voltage or not. The comparison results of the voltage comparing portions 19, 15 are sent to a control portion 21 of a charge/discharge limiting switch 7 to perform the ON/OFF of the switch 7. COPYRIGHT: (C)2000,JPO

Method and apparatus for reducing stand-by power of noncontact charger

Abstract: PROBLEM TO BE SOLVED: To reduce stand-by time power consumption, and additionally to automatically perform non-charging time intermittent operation and charging- time continuous operation on the basis of the magnitude of a primary input current, without bothering a user, by operating a switch device intermittently when charging is not performed or when charging is finished. SOLUTION: A noncontact charger 10 performs charging by connecting a rectifier circuit 18 to a commercial power source 12, connecting a primary power feed coil 22a of an electromagnetic transformer 22 and a switch device 24 to the circuit 18 via a filter capacitor 20, and connecting a battery 36 to the secondary power receiving coil 22b of this transformer 22 through a rectifier circuit, has a current sensor 26 which detects the input current on the primary side of the electromagnetic transformer, and controls switch operation of the switch device 24 causing a control circuit 28 to oscillate intermittently or continuously, on the basis of the relation between the current detected by the sensor 26 and a preset current value.

Electrical energy storage capacitor power supply capable of shorting out defective capacitors

Abstract: There is disclosed a power supply for storing electrical energy in capacitors connected in series, the power supply having a function of shorting out capacitors at fault. Shorting means are connected in parallel with the capacitors, respectively. If any one of the capacitors is charged abnormally, it is detected by detection means. The terminals of this detected capacitor are shorted out by the corresponding one of the shorting means. The shorting means can also act as bypass means ancillary to parallel monitors, respectively. By detecting temperature rises of the bypass means, abnormal charging of the capacitors can be judged.

Generalized procedure for the calibration of switched capacitor gain stages

Abstract: Within the field of integrated circuits used in amplifiers, a structure and improved method for calibrating a switched capacitor gain stage wherein the time required to self-calibrate a switched capacitor gain stage and the associated structure are reduced. The invention utilizes only a single calibration step which is performed while the output of the amplifier being calibrated is monitored. Instead of utilizing a plurality of capacitors C a1 --C an each in parallel with groups of trim capacitors C T , a single capacitor C a is used and connected to switches S 1a1 and S 1b1 . Further, instead of a group of trim capacitors C T being connected in parallel with the capacitor to be trimmed, each of plurality of trim capacitors C T1 -C TN is connected between the input to the operational amplifier and a respective corresponding switch S 1a2 -S 1aN to the input reference voltage node V b0 . As well, switches S 1b2 -S 1bn connect the respective junctions between the trim capacitors C T1 -C TN to ground.

Electrical storage system made of capacitors

Abstract: There is disclosed an electrical storage system comprising capacitors that are prevented from deteriorating at elevated temperatures. The electrical storage system is adapted for use in a hybrid electric vehicle or electric vehicle. The storage system comprises a bank of capacitors, a charger for charging the capacitor bank, a temperature switch connected across the capacitor bank and a discharge resistor connected in series with the temperature switch. The temperature switch is closed at a limit temperature (e.g., 70° C.) at which deterioration of the capacitors can be neglected in a fully charged condition. When the temperature of the capacitor bank reaches the limit value, the temperature switch is closed. The capacitor bank is discharged via both the temperature switch and the discharge resistor. This suppresses deterioration of the capacitors at elevated temperatures.

Methods and apparatus for a high efficiency charge pump that includes a MOSFET capacitor operating in an accumulation region

Abstract: A charge pump circuit includes MOS capacitors configured to operate in the accumulation region, resulting in a substantially constant capacitance over the operational range. In a particularly preferred embodiment, a char ge pump uses multiple stages of p-channel MOS capacitors. In accordance with a further aspect of the present invention, oxide thicknesses of the p-channel MOS capacitors are optimized in accordance with the requirements of each stage.

Power-converting device

Abstract: PROBLEM TO BE SOLVED: To accurately rapidly detect abnormality by detecting a current that is outputted from an initial charging circuit and the terminal voltage of a filter capacitor and comparing a value that is obtained by integrating a current value when starting the charging of the filter capacitor with a value that is obtained by multiplying a voltage value by the capacitance of the filter capacitor. SOLUTION: A power-converting device is composed of an inverter 9, a filter capacitor 7, and a switch 3 that is connected to a charge resistor 4 while the filter capacitor is connected to a DC power supply 1. The output of a current detector 5 and a voltage detector 8 is inputted to a control circuit 10, and internal structure consists of an integrator 11 for integrating the detection value of the current detector 5 with time, an amplifier 12 for multiplying the detection value of the voltage detector 8 by capacitance C of the filter capacitor, a resistor 13 with a specific setting value, and a comparator 14 for comparing a value where the output value of the amplifier 12 is added to that of the resistor 13 with the output value of the integrator 11, thus accurately and rapidly detecting failure and preventing a fault from expanding.

Power systems with cold stand-by using ultra capacitors

Abstract: To achieve a power system of both high reliability and high efficiency, cold stand-by system is promising. It is necessary for this system to hold the output voltage for the duration of switching the malfunctioned power unit to the stand-by unit. Ultra capacitors give an interesting and simple solution to this problem. However, this device has comparatively large internal resistance and this causes power loss. This paper presents a basic study of the loss reduction of the DC power systems with cold stand-by using ultra capacitors. The power losses of the system are simulated and the method to reduce the losses is presented.

An investigation of the endurance of capacitors supplied by nonsinusoidal voltage

Abstract: This paper presents the results of tests performed on small-size capacitors with the aim of investigating the effect of nonsinusoidal voltage on life performance. Harmonic components, as those detectable in ac networks supplying distorting loads, are added to the sinusoidal supply voltage and life tests are carried out under such waveforms. The effects of voltage and current distortion on accelerated electrical aging are modeled and discussed on the basis of statistical techniques, focusing mainly on the features which affect life performance of capacitors. This approach leads to a relationship between expected life and voltage waveform characteristics.

Storage capacitor power supply and method of operating same

Abstract: A storage capacitor power supply has a plurality of electric double layer capacitors connected in series. Each capacitor has connected in parallel therewith a charge-limiting circuit. Each charge-limiting circuit measures a voltage across its corresponding capacitor and causes a charging current to bypass the capacitor when it is charged to a value corresponding to a reference voltage established by the charge-limiting circuit. When all the capacitors are charged to their corresponding reference voltages, the charging current is terminated whereafter the capacitors are discharged with a discharge current. When the capacitors are charged with a recharging current from a partially discharged state, the capacitors are charged to values corresponding to their respective reference voltages at the same time without bypassing the recharging current around one or more of the capacitors.

Design and performance of UHF band inductors, capacitors and resonators using LTCC technology for mobile communication systems

Abstract: We report on basic passive components integrated into ceramic substrate and on the performance of a finite element software package. The inductors of different types in a range of 1 nH to 10 nH show moderate dependence on frequency. Spurious resonances indicate coupling of neighboring structures. Shunt capacitors between 6 pF and 128 pF have resonances in contrast to the series capacitors depending on the ground plane. Stripline and lumped element resonators at 1 GHz showed Q factors around 100 and 50 respectively. Fair agreement of measurement and simulation was observed.

The method of obtaining the adjustable capacitor

Abstract: The method of obtaining the adjustable capacitor permits tranforming all types of capacitors (including electrolytic, vacuum, gas, high-voltage capacitors) into adjustable capacitors without mechanical parts inside capacitors and provides broad ranges of changing the capacity of adjustable capacitors in electric circuits of direct and alternating current and in all types of Marx Generators. The method comprising the steps of: choosing the capacity of one capacitor bigger and connecting said capacitor in series with at least one or two other capacitors; connecting capacitor plates of these capacitors through devices, which change their electrical states; changing the states of said devices within charging and discharging said capacitors and the step of combining plates of said capacitors which ensures the lowest cost price of manufacturing said capacitors. The present invention can be used for controlling the maximum voltage of a load and for changing motor speeed.

Conducted EMI issues in a boost PFC design

Abstract: The paper presents the results of an experimental activity concerned with the development of a 600 W boost power factor corrector (PFC) complying with the EMC standards for conducted EMI in the 150 kHz-30 MHz range. In order to accomplish this task, different circuit design and layout solutions are taken into account and their effect on the conducted EMI behavior of the converter is experimentally evaluated. Common-mode and differential-mode switching noise, together with input filters' design and topology and with the PCB layout (in terms of track length and spacing, ground and shielding planes etc.) are the key aspects which have been analyzed. In particular, the paper reports the conducted EMI measurements for different filter capacitor placements and values, for different power switch drive circuits together with several other provisions which have turned out to be decisive in the reduction of the generated EMI.

Control of power transfer in a flyback converter by modulating the off-phase in function of the load

Abstract: A method of controlling a flyback DC-DC converter, self-oscillating at steady state conditions, employing a transformer for storing and transferring energy to a load and having an auxiliary winding whose voltage, induced by the current flowing in the secondary winding of the transformer, is monitored to regulate the amount of energy being transferred by way of a primary control loop disabling and enabling the turning on of a power switch driving the primary winding of the transformer and to detect its the zero-crossing and consequently turn on the power switch for a new conduction and energy storage phase, the duration (T ON ) of which is established by a secondary control loop of the output voltage producing the turning off of the power switch for a new off phase (T OFF ), and comprising a fixed frequency oscillator of a frequency lower than the self-oscillating frequency of the converter for start-up charge transient of an output filter capacitor, wherein the power transferred from the primary circuit to the secondary circuit of the flyback transformer is controlled by introducing a delay on the turn-on instant of the power switch in respect to a turn-on command generated, during a self-oscillating functioning phase upon sensing a zero crossing event and during a fixed frequency functioning phase, upon a rising front of the signal generated by said oscillator, in function of input variables of the enabling-disabling primary control loop and of the secondary control loop, regardless of the mode of control.