Showing papers on "Capacitor published in 1996"

Materials for electrochemical capacitors: Theoretical and experimental constraints

Abstract: Electrochemical capacitors, also called supercapacitors, are unique devices exhibiting 20 to 200 times greater capacitance than conventional capacitors. The large capacitance exhibited by these systems has been demonstrated to arise from a combination of the double-layer capacitance and pseudocapacitance associated with surface redox-type reactions. The purpose of this review is to survey the published data of available electrode materials possessing high specific double-layer or pseudocapacitance and examine their reported performance data in relation to their theoretical expectations.

High frequency applications based on a new current controlled conveyor

Abstract: When the mixed translinear loop is used in a voltage follower implementation the value of its output resistance depends on its bias current. This property is used in the realization of a current controlled conveyor (CCCII), which has therefore its serial resistance on port X controlled by the bias current. The two basic implementations, that allow from a CCCII and without additive resistances to realize controlled voltage-current converters, are described. A current-controlled voltage-amplifier and a current-controlled current-amplifier are then analyzed. They are implemented from only two CCCIIs and do not require any passive component. The principal implementations for current controlled first-order transfer functions, operating either in voltage-mode or in current-mode, are introduced. They require one or two of the preceding controlled conveyors and use capacitors only. SPICE simulation results, obtained using the parameters of the HF3CMOS process from SGS THOMSON, are given for the CCCII and for its main applications. They confirm the validity of the theoretical analyzes and also underline the high frequency potential of the current controlled implementations introduced. A second-order bandpass filter, operating in voltage-mode, is also described. It is obtained from CCCIIs and two capacitors only. Its centre frequency, which is adjustable by acting on the control currents of the conveyors, is equal to 11.3 MHz for I/sub 0/=20 /spl mu/A and to 16.6 MHz for I/sub 0/=30 /spl mu/A. This variation produces very small changes in both the quality factor and the gain (variations less than 7%). Comparisons between existing OTA circuits and the ones implemented from controlled conveyors, are also given. They underline the advantage which result from implementations using controlled conveyors.

Micro electromechanical RF switch

Abstract: A micro electromechanical RF switch is fabricated on a substrate using a suspended microbeam as a cantilevered actuator arm. From an anchor structure, the cantilever arm extends over a ground line and a gapped signal line that comprise microstrips on the substrate. A metal contact formed on the bottom of the cantilever arm remote from the anchor is positioned facing the signal line gap. An electrode atop the cantilever arm forms a capacitor structure above the ground line. The capacitor structure may include a grid of holes extending through the top electrode and cantilever arm to reduce structural mass and the squeeze damping effect during switch actuation. The switch is actuated by application of a voltage on the top electrode, which causes electrostatic forces to attract the capacitor structure toward the ground line so that the metal contact closes the gap in the signal line. The switch functions from DC to at least 4 GHz with an electrical isolation of -50 dB and an insertion loss of 0.1 dB at 4 GHz. A low temperature fabrication process allows the switch to be monolithically integrated with microwave and millimeter wave integrated circuits (MMICs). The RF switch has applications in telecommunications, including signal routing for microwave and millimeter wave IC designs, MEMS impedance matching networks, and band-switched tunable filters for frequency-agile communications.

CAD models for multilayered substrate interdigital capacitors

Abstract: Conformal mapping-based models are given for interdigital capacitors on substrates with a thin superstrate and/or covering dielectric film. The models are useful for a wide range of dielectric constants and layer thicknesses. Capacitors with finger numbers n/spl ges/2 are discussed. The finger widths and spacing between them may be different. The results are compared with the available data and some examples are given to demonstrate the potential of the models.

Implantable capacitive absolute pressure and temperature monitor system

Abstract: A capacitive pressure and temperature sensing system for providing signals representative of the magnitude of body fluid absolute pressure at a selected site and ambient operating conditions, including body temperature, at the site. An implantable lead having a sensor module formed in its distal end is coupled to a monitor that powers a sensor circuit in the sensor module and demodulates and stores absolute pressure and temperature data derived from signals generated by the sensor circuit. The sensor module is formed with a pickoff capacitor that changes capacitance with pressure changes and a reference capacitor that is relatively insensitive to pressure changes. The sensor circuit provides charge current that changes with temperature variation at the implant site, alternately charges and discharges the two capacitors, and provides timing pulses having distinguishable parameters at the end of each charge cycle that are transmitted to the demodulator. The demodulator detects and synchronizes the timing pulses and derives pressure and temperature analog voltage values representative of the intervals between the timing pulses which are digitized and stored in the monitor. The monitor may also be coupled with other sensors for measuring and storing related patient body parameters, e.g. blood gas, EGM, and patient activity.

Soft breakdown of ultra-thin gate oxide layers

Abstract: The dielectric breakdown of ultra-thin 3 nm and 4 nm SiO/sub 2/ layers used as a gate dielectric in poly-Si gate capacitors is investigated. The ultra-thin gate oxide reliability was determined using tunnel current injection stressing measurements. A soft breakdown mechanism is demonstrated for these ultra-thin gate oxide layers. The soft breakdown phenomenon corresponds with an anomalous increase of the stress induced leakage current and the occurrence of fluctuations in the current. The soft breakdown phenomenon is explained by the decrease of the applied power during the stressing for thinner oxides so that thermal effects are avoided during the breakdown of the ultra-thin oxide capacitor. It is proposed that multiple tunnelling via generated electron traps in the ultra-thin gate oxide layer is the physical mechanism of the electron transport after soft breakdown. The statistical distributions of the charge to dielectric breakdown and to soft breakdown for a constant current stress of the ultra-thin oxides are compared. It is shown that for accurate ultra-thin gate oxide reliability measurements it is necessary to take the soft breakdown phenomenon into account.

Microwave inductors and capacitors in standard multilevel interconnect silicon technology

Abstract: Spiral inductors and metal-to-metal capacitors for microwave applications, which are integrated on a silicon substrate by using standard 0.8 /spl mu/m BiCMOS technology, are described. Optimization of the inductors has been achieved by tailoring the vertical and lateral dimensions and by shunting several interconnect metal layers together. Lumped element models of inductors and capacitors provide detailed understanding of the important geometry and technological parameters on the device characteristics. The high quality factors of nearly 10 for the inductors are among the best results in silicon, particularly when using standard silicon technology.

Electric surgical apparatus

Abstract: PURPOSE: To utilize an electrosurgical apparatus for electric surgical treatment, particularly for tissue cutting, by increasing an output voltage. CONSTITUTION: In an electrosurgical apparatus for drying and cutting a tissue, an electric surgical generator has a negative charge capacitance CL and output inductor L connected in series. The capacitance contains an electrode unit and a cable connected with a generator output 12A. The inductor forms a resonant circuit connected in series. Frequency of the resonant circuit connected in series is typically 1.5f, wherein f is operating frequency. The capacitor is included between conductors and bonded with them. By the conductors, a bipolar electrode 20E is connected with the generator in order to increase negative charge capacitance CL.

Solving the capacitor placement problem in a radial distribution system using Tabu Search approach

Abstract: In this paper, the capacitor placement problem in a radial distribution system is formulated and solved by a Tabu Search (TS) based solution algorithm. The capacitor placement problem considers practical operating constraints of capacitors, load growth, capacity of the feeder and the upper and lower bound constraints of voltage at different load levels to minimize the investment cost of capacitors and system energy loss. A sensitivity analysis method is used to select the candidate installation locations of the capacitors to reduce the search space of this problem a priori. Comparison results of the TS method with the simulated annealing (SA) show that the proposed TS method can offer the nearly optimal solution to the capacitor placement problem within reasonable computing time.

Flexible interconnect film including resistor and capacitor layers

Abstract: A method for fabricating a flexible interconnect film includes applying a resistor layer over one or both surfaces of a dielectric film; applying a metallization layer over the resistor layer with the resistor layer including a material facilitating adhesion of the dielectric film and the metallization layer; applying a capacitor dielectric layer over the metallization layer; and applying a capacitor electrode layer over the capacitor dielectric layer. The capacitor electrode layer is patterned to form a first capacitor electrode; the capacitor dielectric layer is patterned; the metallization layer is patterned to form a resistor; and the metallization layer and the resistor layer are patterned to form an inductor and a second capacitor electrode. In one embodiment, the dielectric film includes a polyimide, the resistor layer includes tantalum nitride, and the capacitor dielectric layer includes amorphous hydrogenated carbon or tantalum oxide. If the resistor and metallization layers are applied over both surfaces of the dielectric film, passive components can be fabricated on both surfaces of the dielectric film. The dielectric film can have vias therein with the resistor and metallization layers extending through the vias. A circuit chip can be attached and coupled to the passive components by metallization patterned through vias in an additional dielectric layer.

High-Permittivity Perovskite Thin Films for Dynamic Random-Access Memories

Abstract: An important application of ferroelectric films is their incorporation into dynamic random-access memories (DRAMs) as the storage node capacitor dielectric. Dynamic random-access memories represent a large market that is experiencing strong growth, but they are particularly significant as the technology leader for semiconductor devices. As products move to higher and higher integration density, new developments are first introduced in DRAMs. The steady trend toward higher density has placed severe demands on the device designs, particularly with respect to “squeezing” the capacitor into the available space.

Transcutaneous energy transmission circuit for implantable medical device

Abstract: An improved transcutaneous energy transmission device (50) is disclosed for charging rechargeable batteries (13) in an implanted medical device (14). A current with a sinusoidal waveform is applied to a resonant circuit comprising a primary coil (9) and a capacitor (25). Current is induced in a secondary coil (10) attached to the implanted medical device. Two solid state switches (21, 22) are used to generate the sinusoidal waveform by alternately switching on and off input voltage to the resonant circuit. The sinusoidal waveform reduces eddy current effects in the implanted device which detrimentally increases the temperature of the implanted device. The present invention charges the batteries using a charging protocol that reduces charging current as the charge level in the battery increases. The controller preferably is constructed as a pulse width modulation device (23) with a variable duty cycle to control the current level applied to the primary coil. An alignment indicator (40) also is provided to insure proper alignment between the energy transmission device and the implanted medical device.

Insulated-gate semiconductor device

Abstract: PURPOSE: To obtain an insulated-gate semiconductor device of a structure, wherein an excess voltage at the time of switching is made low and at the same time, the whole application system comprising a snubber circuit can be constituted compact. CONSTITUTION: An insulated-gate semiconductor device has gate trenches 36, which are respectively provided with a gate electrode 38 via a gate insulating film 37, and an emitter trench 39 arranged with an emitter electrode 40 via a silicon oxide layer 41 and a main current path is provided with a capacitor capacitance by using the layer 41 provided in the trench 39. Accordingly, the insulated-gate semiconductor device of a structure, wherein a surge voltage, which is accompanied by the wiring inductance of a snubber circuit, can be effectively made low and an application system comprising the snubber circuit can be miniaturized, can be formed.

Hybrid energy storage system

Abstract: A hybrid energy storage system (10) including a first energy storage device (12), such as a secondary or rechargeable battery, and a second energy storage device (14), such as an electrochemical capacitor. The electrochemical capacitor provides intermittent energy bursts to satisfy the power requires of, for example, pulsed power communication devices. Such devices typically require power pulses in excess of those which conventional battery cells can easily provide for numerous cycles. The first and second energy storage devices may be coupled to output electronics to condition the output of the devices prior to delivering it to the application device.

A new single-phase active power filter with reduced energy-storage capacity

Abstract: The paper presents an active power filter (APF) circuit which employs a new control method, using an integration and sampling technique, to simplify the calculation algorithm for the real fundamental component of load current. In addition, a new simple control scheme, based on the energy balance concept, is proposed to control the voltage of an energy-storage capacitor. Since the energy change in the energy-storage capacitor can be compensated in the next cycle, and a larger DC bus voltage ripple can be tolerated if a sampling technique is used, a relatively smaller energy storage capacitor is required. The advantages of this APF circuit are simplicity of control circuits, low cost (a smaller energy-storage capacitor) and good transient response. In theory, the time delay for the compensation of reactive power and harmonic currents is zero. The feasibility of this theory is veriffied by using a PSPICE simulation and experimental results.

Nanostructure multilayer dielectric materials for capacitors and insulators

Abstract: A capacitor is formed of at least two metal conductors having a multilayer dielectric and opposite dielectric-conductor interface layers in between. The multilayer dielectric includes many alternating layers of amorphous zirconium oxide (ZrO 2 ) and alumina (Al 2 O 3 ). The dielectric-conductor interface layers are engineered for increased voltage breakdown and extended service life. The local interfacial work function is increased to reduce charge injection and thus increase breakdown voltage. Proper material choices can prevent electrochemical reactions and diffusion between the conductor and dielectric. Physical vapor deposition is used to deposit the zirconium oxide (ZrO 2 ) and alumina (Al 2 O 3 ) in alternating layers to form a nano-laminate.

Qualitative model for the fatigue‐free behavior of SrBi2Ta2O9

Abstract: SrBi2Ta2O9 (SBT) thin films are known to exhibit no polarization fatigue with electric field cycling. However, we have discovered that optical illumination combined with a bias voltage near the switching threshold can result in significant (≳90%) suppression of the switchable polarization of SBT thin film capacitors. A similar effect has also been reported for Pb(ZrxTi1−x)O3 (PZT) capacitors. However, it is found that electric field cycling of the optically fatigued SBT capacitors results in near‐complete recovery of the suppressed polarization. In contrast, electric field cycling of optically fatigued PZT capacitors does not result in any polarization recovery. These results suggest that optical fatigue in both SBT and PZT capacitors results from pinning of domain walls due to trapping of the photogenerated carriers at domain boundaries, whereas the recovery exhibited by SBT thin films indicates that the domain walls are more weakly pinned in SBT than in PZT thin films. Consequently, the fatigue‐free beh...

Structure and Device Characteristics of SrBi2Ta2O9-Based Nonvolatile Random-Access Memories

Abstract: Recently there has been a paradigm shift in nonvolatile computer memories from silicon-technology-based EEPROMs (electrically erasable, programmable read-only memories) to devices in which the stored information is coded into + and − polarizations in thin-film ferroelectric capacitors. Such devices have read and erase/rewrite speeds of the order of 1–35 ns, many orders of magnitude faster than the erase/rewrite speeds of the best EEPROMs (Table I). However, fundamental questions concerning their lifetimes had delayed full commercialization. Because ferroelectrics normally have extremely large dielectric constants, their use as nonswitching capacitors in dynamic random-access memories (DRAMs) is also rapidly evolving. The majority of studies to date have emphasized lead zirconate titanate (PZT)-based capacitors for nonvolatile ferroelectric random-access memories (NVFRAMs) and barium strontium titanate-based capacitor DRAMs (see Table II).

Low cost apparatus for detecting arcing faults and circuit breaker incorporating same

Abstract: A low cost analog arcing detector and a circuit breaker incorporating such a detector provide a variable response time to arcing faults based upon the amplitude of the arcing current. A filter generates pulses having an amplitude proportional to the amplitude of the step increase in current generated by the striking of the arc. The pulses are rectified and the amount by which the single polarity pulses exceed a threshold value, selected to eliminate nuisance trips on current step increases characteristic of some common loads, is integrated by a capacitor connected to a resistor which continually adjusts the capacitor voltage in a sense opposite to that of the pulses. The capacitor and resistor are selected to generate a trip signal as a function of the accumulated, time attenuated magnitude of the step increases in current associated with each striking of the arc current. Preferably, the pulses are squared before the reference current is subtracted to provide faster response for large amplitude arc currents, while avoiding false trips caused by known loads. Preferably, the arcing detector is used with a ground current detector which provides further protection by tripping on ground currents flowing through carbon tracks deposited by arcing currents below the threshold of the arcing fault detector.

Life prediction model for aluminum electrolytic capacitors

Abstract: The aluminum electrolytic capacitor used for DC bus filtering in motor drives is generally thought to be the weak link in motor drive life expectancy. Because, unlike other electronic components in a drive, it has a finite life due to wear-out failure. Although quality improvements have been made to these parts over the last few decades, little has been done to improve the methods used to predict their life. The model presented, based on the physics of the wear-out mechanism, tested favorably against actual data. The model is compared to the existing method which gives substantially more liberal predictions.

Sputtering system using cylindrical rotating magnetron electrically powered using alternating current

Abstract: A sputtering system (50) using an AC power supply (59) in the range of 10 kHz to 100 kHz uses two rotatable cylindrical magnetrons (60, 62). The rotatable cylindrical magnetrons (60, 62), when used for depositing a dielectric layer onto a substrate (80), clean off dielectric material that is deposited onto the target (64, 65). This prevents a dielectric layer on the target (64, 65) from acting like a capacitor and may help avoid arcing. Additionally, an impedance-limiting capacitor (58) can be placed in series in the electrical path between the targets (64, 65) through the transformer (54) so as to reduce arcing. This impedance-limiting capacitor (58) has a value much larger than the capacitor used to couple the power supply (59) to a target (64, 65) in radio frequency sputtering systems.

Dynamic admittance of mesoscopic conductors : discrete-potential model

Abstract: We present a discussion of the low-frequency admittance of mesoscopic conductors in close analogy with the scattering approach to dc conductance. The mesoscopic conductor is coupled via contacts and gates to a macroscopic circuit which contains ac-current sources or ac-voltage sources. We find the admittance matrix which relates the currents at the contacts of the mesoscopic sample and of nearby gates to the voltages at these contacts. The problem is solved in two steps: we first evaluate the currents at the sample contacts in response to the oscillating voltages at the contacts, keeping the internal electrostatic potential fixed. In a second stage an internal response due to the potential induced by the injected charges is evaluated. The self-consistent calculation is carried out for the simple limit in which each conductor is characterized by a single induced potential. Our discussion treats the conductor and the gates on equal footing. Since our approach includes all conductors on which induced fields can change the charge distribution, the admittance of the total response is current conserving, and the current response depends only on ac-voltage differences. We apply our approach to a mesoscopic capacitor for which each capacitor plate is coupled via a lead to an electron reservoir. We find an electrochemical capacitance with density-of-state contributions in series with the geometrical capacitance. The dissipative part of the admittance is governed by a charge-relaxation resistance which is a consequence of the dynamics of the charge pileup on the capacitor plates. We specialize on a geometry displaying an Aharonov-Bohm effect only at nonzero frequencies. For a double barrier with a well coupled capacitively to a gate the low-frequency admittance terms may have either sign, reflecting either a capacitive or a kinetic-inductive behavior. The validity of a second-quantization-current-operator expression which neglects spatial information is examined for perfect leads in both the frequency and the magnetic-field domain. \textcopyright{} 1996 The American Physical Society.

On-the-fly error correction using thermal asperity erasure pointers from a sampled amplitude read channel in a magnetic disk drive

Abstract: In a magnetic disk drive storage system comprising a sampled amplitude read channel and an on-the-fly error correction coding (ECC) system, a thermal asperity compensation technique wherein: a thermal asperity (TA) detection circuit (45) detects a saturation condition in the sample values (25) of the analog read signal (62) which indicates the presence of a TA; a pole of an AC coupling capacitor (55) is elevated; timing recovery (28), gain control (51), and DC offset (44) loops in the read channel are held constant; TA erasure pointers are generated corresponding to the duration of the TA transient; and an on-the-fly error detection and correction (EDAC) circuit processes the TA erasure pointers to correct errors in the detected digital data caused by the TA. Using TA erasure pointers to compensate for the effect of thermal asperities minimizes the cost, complexity, and redundancy of the ECC. Further, soft errors in the prior art method of adjusting the headroom of the read channel ADC are avoided. Still further, the EDAC circuitry can process the erasure pointers on-the-fly and still correct a sufficient number of soft errors without having to perform any significant number of reread operations. In this manner, the disk drive storage system operates virtually uninterrupted in reading data from the disk and transferring it to a host computer.

An on-chip, attofarad interconnect charge-based capacitance measurement (CBCM) technique

Abstract: In this paper, a sensitive and simple technique for parasitic interconnect capacitance measurement with 0.0l fF or 10 aF sensitivity is presented. This on-chip technique is based upon an efficient test structure design. No reference capacitor is needed. The measurement itself is also simple; only a DC current meter is required. We have applied this technique to extract various interconnect geometry capacitances, including the capacitance of a single Metal 2 over Metal 1 crossing, for an industrial double metal process.

Battery impedance monitor

Abstract: A battery impedance monitor includes a driver section having an oscillator which produces a pulsating loading signal which controls periodic loading of the battery to produce at its output terminals a pulsating voltage component having a peak-to-peak amplitude superimposed on the DC output voltage of the battery. This pulsating voltage component is detected in a measuring section, which applies the battery output through a voltage divider to a peak detector which outputs an indicating voltage level proportional to the peak-to-peak amplitude of the pulsating output signal, this indicating level being held on a storage capacitor. The voltage divider includes a Zener diode which shifts the DC level of the battery output without affecting the amplitude of the pulsating component. The measuring section is electrically connected to the driver section only through the battery terminals, but the storage capacitor is coupled to the oscillator through a load resistor and an opto-isolator which provides a discharge path for the storage capacitor during each loading pulse, so that the detector can follow decreasing as well as increasing indicator voltage levels. A delay circuit delays application of the loading pulses to the battery so that the discharge path is removed before the end of each pulse of the battery output voltage.

High value capacitive, replenishable power source

Abstract: The implantable device includes a power supply including a high value, small sized capacitor having at least a capacitive rating of 0.1 farads which is completely contained within the implantable device. This high value, small size capacitor or series of capacitors enables the implantable device to deliver, on a controlled and continual basis, electric energy over at least an eight hour period. Further, the capacitive power source is replenished via an external, RF coupled device on a daily or other long term periodic basis. During the replenishing cycle, the energy contained in the battery of the external transmitter is transferred to the internal capacitive power source in the implantable device. The method includes providing, on an exclusive basis, power to an implantable device via a high value capacitive source during at least an eight hour cycle of substantially continual delivery of electric energy. The method includes incorporating and containing a capacitive device in the implantable device wherein the capacitive device has a capacitive rating of at least 0.1 farads. The capacitive device captures and stores a pre-determined amount of coulombs of electrical energy. This electrical energy is utilized to power the implantable device during at least an eight hour cycle during substantial continual delivery of electrical energy. The replenishment unit can be programmed to interrogate the implanted device and reprogram the implanted device upon detection of a lower power status signal. Also, automatic as well as manually commanded replenishment routines are established between the replenishment unit and the implanted device. Data transmission, error detection routines are established for the programming of the implanted device.

Bidirectional buck boost converter

Abstract: A bidirectional buck boost converter and method of operating the same allows regulation of power flow between first and second voltage sources in which the voltage level at each source is subject to change and power flow is independent of relative voltage levels. In one embodiment, the converter is designed for hard switching while another embodiment implements soft switching of the switching devices. In both embodiments, first and second switching devices are serially coupled between a relatively positive terminal and a relatively negative terminal of a first voltage source with third and fourth switching devices serially coupled between a relatively positive terminal and a relatively negative terminal of a second voltage source. A free-wheeling diode is coupled, respectively, in parallel opposition with respective ones of the switching devices. An inductor is coupled between a junction of the first and second switching devices and a junction of the third and fourth switching devices. Gating pulses supplied by a gating circuit selectively enable operation of the switching devices for transferring power between the voltage sources. In the second embodiment, each switching device is shunted by a capacitor and the switching devices are operated when voltage across the device is substantially zero.