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Showing papers on "Capacitance published in 1986"


Journal ArticleDOI
TL;DR: In this paper, the basic principles of capacitance, and also clarifying some of the misconceptions about the principles of guarding, which were correctly described by Kelvin more than a century ago, are discussed and the possibilities for combining bridge circuits with simultaneous and sequential measurements of complex sensors are described.
Abstract: By reconsidering the basic principles of capacitance, and also clarifying some of the misconceptions about the principles of guarding, which were correctly described by Kelvin more than a century ago, it is shown how guarded multi terminal capacitor geometries can be designed, analytically precalculated and correctly measured using simplified transformer bridge systems with phase-sensitive detection. An overview is given of the archetypal multi terminal capacitor configurations as well as ways to modify them for practical sensor designs. Detrimental side-effects are discussed and rules for practical designs are given. The possibilities for combining bridge circuits with simultaneous and sequential measurements of complex sensors are described. Expectations for future developments, partly based on silicon microfabrication techniques, are discussed and a comparison of the major aspects of capacitive sensors with resistive strain gauges and inductive sensors is given.

201 citations


Journal ArticleDOI
TL;DR: In this article, a general analysis to predict the steady state performance of an isolated self-excited induction generator feeding a balanced R-L load is presented, and the effect of machine core losses has also been considered.
Abstract: A general analysis to predict the steady state performance of an isolated self-excited induction generator feeding a balanced R-L load is presented. In the analysis the effect of machine core losses has also been considered. It is shown that besides voltage and frequency the analysis can be used to predict the minimum value of terminal capacitance required for excitation as well as for maintaining a constant terminal voltage. Comparison of the predicted and the experimental results shows a good agreement.

174 citations


Journal ArticleDOI
TL;DR: In this article, the authors present a model of the double layer of a semiconductor/molten salt interface with the first explicit contributions from the solvent and electronic structure and give an excellent description of the interfacial capacitance with at most one parameter.

169 citations


Journal ArticleDOI
TL;DR: Inversion-layer capacitance has been experimentally characterized and identified to be the main cause of the second-order thickness-dependence of MOSFET characteristics as discussed by the authors, and empirical equations for inversion layer capacitance and mobilities versus electric field are proposed.
Abstract: Inversion-layer capacitance has been experimentally characterized and identified to be the main cause of the second-order thickness-dependence of MOSFET characteristics. Field-dependent channel mobilities of both electrons and holes were independent of gate-oxide thicknesses from 50 to 450 A, e.g., there is no evidence of the alleged mobility degradation in very thin gate-oxide MOSFET's. Subthreshold slope, insignificantly affected by the inversion-layer capacitance, follows the simple theory down to ∼ 35 A of oxide thickness. The empirical equations for inversion-layer Capacitance and mobilities versus electric field are proposed.

138 citations


Journal ArticleDOI
TL;DR: In this paper, a finite-element approach to the quasi-TEM analysis of several different types of isolated and coupled microwave transmission lines is described, where the first and higher order ordinary elements, as well as singular and infinite elements, are used to solve for the potential and field distributions in the cross section of the line.
Abstract: This paper describes a finite-element approach to the quasi-TEM analysis of several different types of isolated and coupled microwave transmission lines. Both the first- and higher order ordinary elements, as well as singular and infinite elements, are used to solve for the potential and field distributions in the cross section of the line. Next, the cross-sectional field distribution is inserted in a variational expression to compute the capacitance per unit length of the line, and the effective permittivity and characteristic impedance of the line are obtained from the capacitance value. A perturbational approach is developed for estimating the losses due to conductor and dielectric dissipation and computing the attenuation constant. Both the upper and lower bounds for the capacitance and the characteristic impedance are found by solving the original and the corresponding dual problem. Lines treatable by this method may contain an arbitrary number of arbitrarily shaped conductors, including a system of conductors placed either above a single ground plane or between two parallel ground planes, and inhomogeneous dielectric regions that can be approximated Iocally by a number of homogeneous subregions. The results obtained using the finite-element procedure have been compared for various types of microwave transmission lines and have been found to agree well with available theoretical and measured data.

132 citations


Patent
15 Jul 1986
TL;DR: In this article, a high efficiency RF capacitive spark plug with a projecting antenna tip was used for forming very large spark gaps to the plug shell and piston face as well as for coupling high electric fields to the local initial flame plasma, which was used in combination with shielded high voltage cable including series inductive choke elements and a Capacitive Discharge ignition system incorporating an input capacitor, a SCR switch, an ignition coil with an optimized high current and high output voltage, and preferably a synchronous DC-DC power converter providing "boost power" during ignition so that substantial
Abstract: An Electromagnetic Ignition system suitable for adaptation to standard automobile engines including diesel engines, which has been improved by means of a high efficiency RF capacitive spark plug with a projecting antenna tip used for forming very large spark gaps to the plug shell and piston face as well as for coupling high electric fields to the local initial flame plasma, preferably used in combination with shielded high voltage cable including series inductive choke elements and a Capacitive Discharge ignition system incorporating an input capacitor, a SCR switch, an ignition coil with an optimized high current and high output voltage, and preferably a synchronous DC-DC power converter providing "boost power" during ignition so that substantial capacitive, inductive, and electromagnetic energy is supplied to the air-fuel mixture. Preferably the coil has a turns ratio of 50 with the input capacitor having a capacitance between 5 and 10 microfarads and a 400 volts rating. Large output capacitance is provided naturally by existing coil and shielded cable capacitance, supplemented with large plug capacitance of 50 to 250 picofarads, which are charged up to between 15 and 30 Kilovolts prior to breakdown of the wide variable spark gap producing: high frequency capacitive sparks, large inductive spark of several amps; and high pulsed local EM electric field strength of thousands of volts/cm providing a practical, highly efficient ignition system capable of igniting very lean air-fuel mixtures for reducing exhaust emissions and increased engine efficiency.

130 citations


Patent
15 Oct 1986
TL;DR: In this article, a capacitive occupancy detector is used for detecting the capacitance formed between the first and second electrodes and a processor is provided for storing capacitance at predetermined periods to determine the presence of a person when the difference between the last capacitance detected and a capacitance previously stored is detected.
Abstract: A capacitive occupancy detector apparatus includes a personnel containment device having first and second electrodes which will define an electric field therebetween which will be intercepted by a person present in the containment device. A detecting device is provided for detecting the capacitance formed between the first and second electrodes and a processor is provided for storing the capacitance at predetermined periods. The difference between the last capacitance detected and a capacitance previously stored is detected to determine the presence of a person when the difference indicates an increase of the capacitance exceeding a first predetermined threshold. A second threshold is set based upon the capacitance which determines the presence of a person so that the subsequent determination of the absence of a person is based upon detecting a decrease of the capacitance with respect to the second threshold.

113 citations


Patent
Shinichiro Kimura1, Hideo Sunami1
01 Dec 1986
TL;DR: In this paper, a process for producing a memory cell having a stacked capacitor is described, where projections and recesses are provided on the surface of a capacitance electrode to increase the storage capacitance.
Abstract: A process for producing a memory cell having a stacked capacitor. As the reduction in device size of memory cells progresses, it becomes difficult to obtain a satisfactorily large capacitance even with a stacked capacitor structure. To enable a larger capacitance to be obtained for the same occupied area, projections and recesses are provided on the surface of a capacitor electrode. It is possible, according to the process, to readily produce projections and recesses for increasing the storage capacitance.

100 citations


Patent
09 Dec 1986
TL;DR: In this article, a level detecting capacitance is used to detect the level of the oil or transmission fluid in both normal and extreme temperature conditions, where the only active components of the sensor have input and leakage currents substantially lower than those of diodes and current sources under high temperature conditions.
Abstract: A sensor for sensing the level of oil or transmission fluid under both normal and extreme temperature conditions. The only active components of the sensor have input and leakage currents substantially lower than those of diodes and current sources under high temperature conditions. The sensor has a probe, including a pair of electrodes forming a level detecting capacitor, adapted to extend in the vessel to detect the level of the liquid. A reference capacitor is included which has a capacitance substantially the same as the capacitance of the level detecting capacitor when no dielectric liquid is present between the electrodes of the level detecting capacitor. Circuitry is provided for measuring the capacitance of each capacitor and for deriving from the capacitance measurements a signal proportional to the level of the dielectric liquid at the sensor. Circuitry is also provided for testing whether the reference capacitor is operating properly. One of the electrodes of the level detecting capacitor is insulated to render the output of the sensor independent of high temperature conductivity effects. Structure and a method are provided for compensating for varying dielectric constants of the oil or transmission fluid in which the sensor is immersed.

98 citations


Journal ArticleDOI
TL;DR: In this paper, the authors combined the explicit enthalpy method and Pham's three-level enthalhip method to obtain a diagonal capacitance matrix, which can be used to estimate the specific heat near the phase change point.

88 citations


Journal ArticleDOI
TL;DR: In this paper, a feedback charge measurement circuit is used to reduce the effect of several significant error terms, which has the advantages of higher signal-to-noise ratio at the frequencies of interest, independence of signal size from measurement time, and ease of distinction of signal charge from error currents at the time of measurement.
Abstract: A method is described for the measurement of quasistatic CV characteristics in semiconductors which offers significant advantages over previous methods. Using a small voltage step across the device under test, a displacement charge is stimulated and measured. A feedback charge measurement circuit is used, reducing the effect of several significant error terms. This technique has the advantages of higher signal‐to‐noise ratio at the frequencies of interest, independence of signal size from measurement time, and ease of distinction of signal charge from error currents at the time of measurement. Results consistent with those of previous techniques have been obtained on silicon MOS capacitors and other devices using steps from 10 to 100 mV and delays between step and measurement of up to 200 s. Furthermore, the method has been extended to provide additional information useful in determining whether an equilibrium measurement is obtained and in diagnosing and correcting for errors due to dc leakage currents. ...

Journal ArticleDOI
TL;DR: In this article, the capacitance of an open-ended coaxial line immersed in a bilayered medium is evaluated both numerically and experimentally, and a quasi-static solution for the fringe-field capacitance was obtained using the method of moments.
Abstract: The capacitance of an open-ended coaxial line immersed in a bilayered medium is evaluated both numerically and experimentally. Water layers of varying thickness backed by air and metal walls were assumed, and a quasi-static solution for the fringe-field capacitance was obtained using the method of moments. The numerical results compare well with experimental values obtained using an automated network analyzer. The two configurations, namely the metal and air wall, represent the upper and lower bound of the capacitance change from the homogeneous case, respectively. For a typical 6.4-mm (0.25-in)-diam sensor, the change in the sensor capacitance as compared with a homogeneous case is less than 1% for layers thicker than 6 mm. The results provide information on the response of the sensor when used to measure the properties of layered dielectrics.

Journal ArticleDOI
TL;DR: The results of a high accuracy numerical study of the uniformity of the electric field between parallel disc electrodes are reported in this article, where simple analytical expressions are derived describing the field behaviour at points on the electrodes near the edges of the discs and also at points between the electrodes remote from the edges.
Abstract: The results of a high accuracy numerical study of the uniformity of the electric field between parallel disc electrodes are reported Simple analytical expressions are derived describing the field behaviour at points on the electrodes near the edges of the discs and also at points between the electrodes remote from the edges These expressions are consistent with the numerical results A simple approximation for the fringing capacitance of parallel-plate electrode systems of arbitrary shape is also given This expression leads to a first-order approximation for the total capacitance which, for disc electrodes, has superior accuracy to similar published approximations for radii up to five times the disc separation A higher-order approximation for the capacitance is shown to have markedly better accuracy than any first-order approximation

PatentDOI
TL;DR: In this article, an arrangement for coupling electrical energy into and/or out of a surface acoustic wave (SAW) device, such as a transponder, was disclosed, where an inductive loop, formed by at least one turn of an electrical conductor, is connected to the two input/output terminals of the SAW device.
Abstract: An arrangement is disclosed for coupling electrical energy into and/or out of a surface acoustic wave (SAW) device, such as a transponder. The SAW device has two input/output terminals electrically connected to at least one transducer for converting between electrical energy and SAW energy. Such transducer presents to the terminals a prescribed capacitance in the frequency range of operation. An inductive loop, formed by at least one turn of an electrical conductor, is connected to the two input/output terminals of the SAW device. The inductance of the loop is made substantially equal to the prescribed capacitance at the frequency range of operation, thus forming a resonant circuit with the SAW device. The loop also forms a protective DC short circuit across the two terminals, preventing build-up of static electricity. The inductive loop is inductively coupled to an antenna capable of receiving and/or transmitting radiation in the frequency range of operation.


Journal ArticleDOI
TL;DR: In this paper, a theoretical model for capacitance and transconductance frequency dispersion in MESFETs at low drain bias is developed and compared with experimental data obtained on commercial and special devices, and the results are consistent with a model in which the surface states have a density N SS in the range of 10 13 cm −2 eV −1 and are distributed over a depth of approximately 100 A below the surface.
Abstract: A theoretical model is developed for capacitance and transconductance frequency dispersion in MESFETs at low drain bias and is compared with experimental data obtained on commercial and special devices. It is shown that the results are consistent with a model in which the surface states have a density N SS in the range of 10 13 cm −2 eV −1 and are distributed over a depth of approximately 100 A below the surface. It is found that a small N SS contributes to an increase of the g m dispersion and that the dispersion is minimized in recessed gate structures. Finally it is emphasized that g m frequency measurements are very convenient for surface characterization and mostly for the evaluation of the spatial distribution of the interface traps when other techniques are inoperative.

Journal ArticleDOI
02 Jun 1986
TL;DR: In this paper, the authors analyzed the effect of light-induced voltage and the change in the source-to-drain channel current under optical illumination higher than the semiconductor band gap for GaAs MESFETs, Al/sub 0.7/As/GaAs high electron mobility transistor (HEMT), and GaAs PBT.
Abstract: Light-induced voltage and the change in the source-to-drain channel current under optical illumination higher than the semiconductor band gap for GaAs MESFET, InP MESFET, Al/sub 0.3/Ga/sub 0.7/As/GaAs high electron mobility transistor (HEMT), and GaAs permeable base transistor (PBT) are analytically obtained. The GaAs PBT and GaAs MESFET have higher sensitivity than the InP MESFET. However, the Al/sub 0.3/Ga/sub 0.7/As/ GaAs HEMT is observed to have the highest sensitivity. Variations in the small-signal parameters, such as channel conductance, gate-to-source capacitance, and transconductance, as well as transient parameters, such as switching time and power-delay product, of GaAs MESFET with illumination are computed. The computed capacitance and transconductance are compared with the experimentally obtained values and are found to be in fair agreement. Based on these results, the design considerations for an optically controlled MESFET switch are discussed. Finally, variation in device parameter due to optical illumination and its effect on the cutoff frequencies f/sub T/ and f/sub max/ are also investigated.

Patent
10 Dec 1986
TL;DR: In this paper, a memory cell has a first capacitance between a floating gate and a channel region, and a second capacitance is less than the first, and there is self-alignment in two directions, resulting in a compact cell.
Abstract: A memory cell has a first capacitance between a floating gate and a channel region and a second capacitance between a control gate and the floating gate. The second capacitance is less than said first capacitance, preferably much less, and there is self-alignment in two directions, resulting in a compact cell. The floating gate can have a textured surface facing the control gate. The control gate can also shift the cell operation from the enhancement mode into the depletion mode.

Journal ArticleDOI
TL;DR: In this article, a four-channel optoelectronic integrated receiver array operating at the wavelength near 850 nm has been fabricated on a single GaAs substrate by using metal-semiconductor-metal (MSM) photodiodes (PD's) and metal-semmiconductor field effect transistors (MESFET's).
Abstract: A four-channel optoelectronic integrated receiver array operating at the wavelength near 850 nm has been fabricated on a single GaAs substrate by using metal-semiconductor-metal (MSM) photodiodes (PD's) and metal-semiconductor field-effect transistors (MESFET's). The largest integration scale for a monolithic receiver and uniform characteristics among circuit channels have been achieved due to the structural simplicity and the process-compatibility of this array. Also, an extremely small capacitance of MSM-PD, 0.10 pF, has lead us to obtain a high-speed operation up to a bit rate of 1.5 Gbit/s, NRZ, and a low noise characteristic exhibiting an equivalent input noise current as small as 5 pA/Hz1/2. These results have indicated the suitability of MSM-PD/MESFET's circuits for large-scale multichannel optoelectronic integration of receivers.

Journal ArticleDOI
TL;DR: In this paper, the particular component values which result in the smallest component stresses are determined, and a simple design strategy is developed, which is illustrated for an off-line 200 W, 5 V application.
Abstract: For a given output voltage and power, the peak resonant capacitor voltage and peak inductor and switch currents of the series resonant converter depend strongly on the choice of transformer turns ratio and of tank inductance and capacitance. In this paper the particular component values which result in the smallest component stresses are determined, and a simple design strategy is developed. The procedure is illustrated for an off-line 200 W, 5 V application, and it is shown that an incorrect choice of component values can result in significantly higher component stresses than are necessary.

Patent
20 Feb 1986
TL;DR: In this paper, a planar capacitance with a central region and an outer region separated by a dielectric area is used to form a spiked output pulse from a drive input pulse having at least one stepped edge.
Abstract: A proximity sensing device comprising a sensor including a planar capacitor (1) having a central region (1a) and an outer region (1b) separated by a dielectric area, differentiator means (2, 3) associated with said capacitor to form a spiked output pulse from a drive input pulse having at least one stepped edge and comparator means (10) to repeatedly compare said spiked output pulses with a reference datum indicative of no proximity body being located adjacent to or touching said sensor to determine if such a proximity body is so located. The ratio of the perimeters of the central region and dielectric area of the planar capacitor is approximately 2:1 and its capacitance is comparable to that of a human finger.

Patent
10 Mar 1986
TL;DR: In this article, a dielectric filter for use in a microwave integrated circuit includes a substrate made of ceramics and a plurality of capacitance electrodes mounted on the substrate.
Abstract: A dielectric filter for use in a microwave integrated circuit includes a substrate made of ceramics and a plurality of dielectric resonators mounted on the substrate. The substrate has a ground electrode, input and output strip lines, and a plurality of capacitance electrodes. The dielectric resonator has a body made of a dielectric material with a through hole formed therein, an inner electrode deposited on the wall defining the through hole, and an outer electrode deposited on an outer surface of the body. The inner electrode is electrically connected to the capacitance electrode, and the outer electrode is electrically connected to the ground electrode.

Patent
29 May 1986
TL;DR: A passive marker is a tuned circuit having an inductance and a capacitance carried by a carrier enclosed within a hollow sphere that is partially filled with a liquid to freely float the carrier as discussed by the authors.
Abstract: A passive marker including a tuned circuit having an inductance and a capacitance carried by a carrier enclosed within a hollow sphere that is partially filled with a liquid to freely float the carrier. The inductance includes a coil which, when the carrier is floating, positions the axis of the coil so it is closer to the vertical than the horizontal. The passive marker is of a type that is buried relative to portions of utilities such as gas, telephone, water and power lines, for use in locating such portions when necessary.

Patent
James E. Mitzlaff1
14 Apr 1986
TL;DR: In this article, a high efficiency RF power amplifier is disclosed in which a field effect transistor is operated in a class F mode, and a third harmonic quarterwave open circuit transmission line stub having a Z O adjusted to provide capacitance series resonant with transistor inductance at the second harmonic is coupled to the transistor output lead to produce a low impedance at the channel drain.
Abstract: A high efficiency RF power amplifier is disclosed in which a field effect transistor is operated in a class F mode. A third harmonic quarterwave open circuit transmission line stub having a Z O adjusted to provide capacitance series resonant with transistor inductance at the second harmonic is coupled to the transistor output lead to produce a low impedance at the channel drain of the transistor. Parallel resonance of the transistor die capacitance and interconnect inductance coupled to ground by the transmission line produces a third harmonic high impedance at the channel drain. Further lowpass output matching circuitry provides a constantly increasing impedance magnitude from the transistor die to the load and provides load mismatch isolation to the second and third harmonic impedances at the channel drain.

Journal ArticleDOI
TL;DR: In this article, a three-terminal model for the high electron mobility transistor (HEMT) using chargevoltage relationships derived from the Boltzmann transport was formulated, where the current transport of the two-dimensional electron gas (TEG) and the capacitance of the embedded parasitic MESFET structure were modeled.
Abstract: A three-terminal model is formulated for the high electron mobility transistor (HEMT) using charge-voltage relationships derived from the Boltzmann transport. Emphasis is placed on modeling the current transport of the two-dimensional electron gas (TEG) and the capacitance of the embedded parasitic MESFET structure. Furthermore, a distributed circuit topology is used to better model high-frequency effects, such as the transit time delay, in both small-signal and large-signal-transient analysis. The HEMT model is implemented in the circuit simulation program HP-SPICE. Both dc and ac simulation results are discussed.

Journal ArticleDOI
TL;DR: In this article, the capacitance data largely obey expectations from an insulator model and combine with previous ellipsometric data to reveal the main charge and potential distribution at the passive titanium electrode.

Patent
29 Sep 1986
TL;DR: In this article, a voltage controlled oscillator is tuned with a network comprising two varactor diodes and two transmission lines, and the overall reactance of the network is such that, when a varactor tuning voltage is varied, the output frequency of the voltage-controlled oscillator will vary in an fashion with respect to the tuning voltage.
Abstract: A voltage controlled oscillator is tuned with a network comprising two varactor diodes and two transmission lines. By selecting appropriate values of varactor capacitance and transmission line length and width the overall reactance of the network is such that, when a varactor tuning voltage is varied, the output frequency of the voltage controlled oscillator will vary in an fashion with respect to the tuning voltage. Such a voltage controlled oscillator is gain compensated and exhibits a controlled modulation sensitivity over a range of frequencies. If the required frequency range of the oscillator is known beforehand, an alternate embodiment of the invention may be employed in which one of the varactor diodes is replaced with a fixed capacitor having a suitable value for the desired frequency range.

Journal ArticleDOI
TL;DR: In this article, the majority carrier conductance due to the hole flow towards the surface of a wafer from the bulk has been formulated following the half-sided junction model, and an empirical equation for the carrier drift velocities in very high electric fields has been proposed for the formulation.
Abstract: The majority carrier conductance due to the hole flow towards the surface of a wafer from the bulk has been formulated following the half-sided junction model previously reported An empirical equation for the carrier drift velocities in very high electric fields has been proposed for the formulation Besides the conductance, the depletion layer capacitance, interface trap capacitance and conductance are found to be responsible for ac surface photovoltages in the depletion case The majority carrier conductance can explain the formerly observed conductance of 27 S/m2 in a 76-mm-diameter 10-mΩm oxidized p-type Si wafer Analysis of the formerly reported surface photovoltages reveals a surface potential, fixed oxide charge density, hole capture cross section and interface trap density of 032 V, 17 mC/m2, 20×10-20 m2 and 20×1016 m-2 eV1 respectively

Patent
Mati Mikkor1
30 Oct 1986
TL;DR: In this paper, an insulating layer is attached to the first and second wafers of a variable capacitance pressure sensor to prevent electrically conductive coupling between the two semiconductor paths.
Abstract: A silicon variable capacitance pressure sensor has two silicon wafers. The first wafer has a first capacitor plate contacting a highly doped first semiconductor path through the first wafer. The second wafer has a second capacitor plate contacting a highly doped second semiconductor path through the second wafer. An insulating layer is attached to the first and second wafers for preventing electrically conductive coupling between the first and second wafers, thereby reducing parasitic capacitance between the first and second semiconductor paths.

Patent
17 Mar 1986
TL;DR: In this article, a system for indicating the level of material in a vessel as a function of material capacitance comprising a resonant circuit including a capacitance probe adapted to be disposed in the vessel so as to be responsive to variations in capacitance at the probe and the reference signal is presented.
Abstract: A system for indicating the level of material in a vessel as a function of material capacitance comprising a resonant circuit including a capacitance probe adapted to be disposed in a vessel so as to be responsive to variations in capacitance as a function of material level. An rf oscillator has outputs coupled to the resonant circuit and to a phase detector for detecting variations in phase angle as a function of probe capacitance. Level detection circuitry is responsive to an output of the phase detector and to a reference signal indicative of a predetermined level of material for indicating material level as a function of a difference between capacitance at the probe and the reference signal. An automatic calibration circuit adjusts the resonance characteristics of the parallel resonant circuit. A remote module provides facility for initiating a system-test and a system-calibrate operation, either individually or sequentially.