Showing papers on "Capacitor published in 1978"

Method for automatically matching a radio frequency transmitter to an antenna

Abstract: A plurality of series inductors and shunt capacitors are provided between a radio transmitter and an antenna The inductors and capacitors are arranged in binary increments and are inserted in, or withdrawn from the circuit via provided reed relays A microprocessor activates the relays in one of several modes until the required degree of match is provided The status of the relays is stored in provided memory such that upon tuning of the transmitter to the same channel a proper match condition can be established without resort to the matching program

High-voltage converter circuit

Abstract: An inverter circuit includes a DC voltage supply having a plurality of voltage taps coupled via (1) a first plurality of diodes for unidirectional current flow therefrom to successive common connections between the upper half of a plurality of first transistors connected in cascade across the voltage supply, (2) a second plurality of diodes for unidirectional current flow therefrom to successive common connections between the upper half of a plurality of capacitors, of like number to the first transistors, connected in series and across the DC voltage supply via a pair of diodes providing unidirectional current between the voltage supply and capacitors, (3) a third plurality of diodes for unidirectional current flow thereto from successive common connections between the lower half of the plurality of first transistors, (4) a fourth plurality of diodes for unidirectional current flow thereto from the successive common connections between the lower half of the plurality of capacitors; and a plurality of second transistors connected in cascade across the series string of capacitors, their centralmost common connection being connected to an output terminal, individual ones of a fifth plurality of diodes being connected between successive common connections of the capacitors to and for unidirectional current flow (1) therefrom to the successive common connections between the upper half of, and (2) thereto from the successive common connections between the lower half, of the second transistors, the pluralities of first and second transistors being operable to different combinations of their conductive and nonconductive states for predetermined periods of time for producing a multitiered AC waveform at the output terminal.

Intracranial pressure implant

Abstract: An implantable transensor device containing a passive RF resonant circuit having a natural frequency influenced by the pressure of the sensor's environment in a body cavity of a living entity. The circuit of the transensor includes an inductor and a capacitor, at least one of which varies in value in direct relation to variation of environmental pressure to change the resonant frequency of the circuit. The circuit can be externally interrogated to determine the resonant frequency thereof at any point in time by the imposition thereon of swept frequency electromagnetic radiation provided by a monitoring device which determines when some of the radiation is absorbed as a result of the frequency of the radiation being the same as the resonant frequency of the transensor circuit. An imposed relationship exists between the sensed environmental pressure, and the reactance of the reactive components of the circuit. A natural relationship exists between pressure sensitive reactance, and the resonant frequency of the circuit. As a result, an increase in environmental pressure causes a corresponding increase in frequency and a decrease in environmental pressure causes a decrease in frequency.

Capacitive touch switch array

Abstract: A capacitive touch panel comprising an array of touch sensitive switch cells, the panel including relatively small area touch switch elements located on closely spaced centers, that can be of transparent construction particularly suited for use with data processing equipment and electronic displays. Each switch cell includes a first and a second pair of series connected capacitors energized by a common signal source, the array of switch cells being arranged so that the first pair of capacitors are connected in first groups of switch cells, such as rows, to a corresponding first plurality of signal detectors, and the second pair of capacitors are connected in second groups of switch cells, such as columns, to a corresponding second plurality of signal detectors, the junctions of each pair of capacitors of a single switch cell being selectively coupled to ground by the body or other touch capacitive means for actuating a selected switch cell.

Single slope A/D converter with sample and hold

Abstract: A converter circuit employs a capacitor coupled through a selector switch to an analog voltage so that the capacitor is charged to the analog level. When a conversion is commanded, the capacitor is disconnected from the analog voltage and discharged through a constant current load. This results in a linear voltage ramp. A comparator senses the capacitor voltage and compares it to a reference level that is slightly above ground. Upon starting the ramp an increment of voltage slightly larger than the reference is applied in series with the capacitor. When the ramp drops below the reference level the comparator output is used to terminate the conversion interval. Thus, the conversion interval is directly and linearly proportional to the magnitude of the analog voltage. If desired, the conversion interval can be used to operate a counter to provide a conventional digital readout. Alternatively, the device can be operated by a microprocessor with the readout being sensed and displayed if desired by the microprocessor. Due to the increment of voltage, the zero analog voltage conversion interval is a fixed finite time.

Linear synchronous motors

Abstract: PURPOSE:To obtain an excellent damping characteristic using a simple structure by setting up a damping means consisting of external impedance in which resistors and capacitors are arranged in series or in parallel between the input terminals of an armature coil.

Charge circuits for analog LSI

Abstract: Precision analog integrated circuits may be realized using MOS transistors and accurately ratioed MOS capacitors. Compatibility with high-density digital MOS circuits leads to the possibility of fully Integrated subsystems employing both analog and digital circuitry. This paper presents a unified view of sampled-data charge-conserving circuits for analog-to-digital (A/D) and digital-to-analog (D/A) converters and audio frequency filters.

Force measuring capacitor

Abstract: A capacitor comprising at least two electrodes separated from one another by an elastic dielectric formed of rubber and/or plastic for measuring forces acting upon one of the electrodes--the so-called measuring electrodes--by detecting the resultant change in capacitance. The dielectric in its unloaded state is pre-compressed and preferably possesses a number of hollow spaces.

A precision FET-less sample-and-hold with high charge-to-droop current ratio

Abstract: A monolithic sample-and-hold amplifier designed without field-effect transistors is described. Various sample-and-hold configurations are compared and their merits are discussed. Unique features of the design include a diode-bridge switch and a current booster with 50 mA of drive capability to charge the hold capacitor during large signal acquisition. The output amplifier's operating conditions are changed under logic control; it functions as a fast follower in the sample mode, and as a low input current amplifier in the hold mode. Performance characteristics include: 3.5-/spl mu/s acquisition time to 0.1 percent with a 5000-pF hold capacitor, 50 pA of droop current from 0 to 70/spl deg/C, 10/SUP 9/ charge-to-droop current ratio, and 0.3 mV of zero-scale error.

A Frequency Shift Dielectric Soil Moisture Sensor

Abstract: Field implantable and laboratory sensors for the measurement of moisture in soil based on the increase of soil dielectric permittivity with volume fraction of water were developed. A typical sensor consists of a case containing a high-frequency (31-MHz) oscillator whose frequency determining resonance LC network is coupled to the built-in electrode via a capacitor T network. Increases in moisture cause a shift in the resonance frequency, which is detected by an external differential frequency counter or readout. The T network and electrode electronic switches reduce the undesirable influence of soil conductivity on the frequency shift. Although the sensor contains active elements, it acts as a passive transducer since power is supplied to the sensor from the readout unit through the two-conductor cable which transmits the RF.

Voltage multiplier employing clock gated transistor chain

Abstract: A voltage multiplier circuit arrangement comprises a plurality of transistors connected a series between an input and an output of said arrangement, and first and second input lines arranged to have differential alternating voltage applied between them. Successive junctions between adjacent transistors are connected via respective capacitors to alternate ones of the first and second input lines. The control electrode (e.g. the gate or base electrode) of each one of said transistors is connected to a junction of two adjacent transistors, the latter being nearer to the output of said arrangement than is the one transistor. The junction is connected via one of the capacitors with the input line with which said one transistor is connected.

Method of making multiple electrical components in integrated microminiature form

Abstract: Integrated structures of various combinations of inductors, capacitors and resistors are formed by bonded laminations of films of electrical conductors of desired configurations and electrical properties separated by films of dielectric material. Electrical terminals extending from appropriate ones of the conductors may be interconnected selectively to provide various single, series and parallel circuit component arrangements.

Ballast structure for central high frequency dimming apparatus

Abstract: An illumination control system for gas discharge lamps which can be dimmed is provided in which a central inverter produces sinusoidal output voltage at about 23 kHz. The amplitude of the inverter output is adjustable to dim the lamps. A transmission line consisting of spaced wires having respective thick insulation sheaths distributes the high frequency power to remotely located assemblies of ballasts and lamps. A high power factor rectifier network is disclosed for providing a d-c input to the inverter from the 50/60 Hz mains. Several ballasts are disclosed, which consist principally of circuits using passive linear components. Some of the ballasts disclosed are conjugate ballasts which are those made of complex conjugate impedances which resonate with or near the input power frequency. Some ballasts disclosed are non-linear when the lamp is out in order to limit the open circuit voltage. The ballasts disclosed all have the following characteristics: (a) good power factor (above 0.8) and include at least one capacitor and one inductor; (b) are dimmable by at least 50% by a variable amplitude input having a substantially continuous wave form; (c) use only two input wires; (d) operate at a relatively high frequency (at least an order of magnitude above line frequency); (e) a good current crest factor.

Trim structure for integrated capacitors

Abstract: A capacitor suitable for integration into a monolithic integrated circuit is fabricated in two parallel connected sections. One section, using a thin oxide, constitutes most of the capacitance. A second section fabricated on a thick oxide constitutes a smaller capacitance per unit area but can be laser trimmed to provide a precise capacitance without damage to the integrated circuit. The trimmable section is desirably made using a conductive electrode material that is readily removed with laser energy.

Multi-mode relaxation oscillator

Abstract: In a relaxation oscillator where the oscillation frequency is proportional to the charge rate of a capacitor, independent current sources are connected through separate switches to change the charge rate of the capacitor and thus the oscillation frequency. Each switch is controlled by signals from a separate detector of a condition which requires that the oscillation frequency be changed. An oscillation frequency increase between the standby and alarm modes of a smoke detector is accomplished in one disclosed embodiment and duty cycle means for controlling the operative period of the alarm indicator during each cycle of the increased oscillator frequency is disclosed in a more particular embodiment.

Windshield mounted half-wave communications antenna assembly

Abstract: A half-wave length communications antenna assembly especially adapted to be mounted on non-conductive surfaces, such as on a window of a vehicle. The antenna assembly desirably includes an electrically shortened half-wave inductively loaded radiating whip loaded at its base end by a loading capacitor plate to be fixed to a non-conductive surface. The whip is coupled through the non-conductive surface to a transmission line internally of the vehicle by a coupling capacitor plate which, with the loading capacitor plate, forms a coupling capacitor. A tuned circuit which is tuned to the nominal resonant frequency of the whip is connected to the coupling capacitor plate and serves as an impedance matching circuit between the half-wave whip and the transmission line. The tuned circuit also affects the radiation pattern of the whip to produce a pattern more typical of a five-eighths wave length antenna to provide somewhat greater gain.

Sensing circuit for a multi-level signal charge

Abstract: This multi-level signal charge sensing circuit includes a first capacitor for holding inspected charge, a second capacitor for holding a plurality of reference charge levels and a comparator for comparing potentials produced at the first and second capacitors. As the plurality of reference charge levels, (N-1) charge levels of different known values are prepared. The inspected charge is given to the first capacitor which is reset, and the (N-1) reference charge levels are successively given from the highest or lowest level to the second capacitor which is also reset. The comparator is operated for every step of supplying each reference charge level. Of the successive reference charge supplying steps at an instant between the steps corresponding to 0 and (N-1), the output state of the comparator is inverted, thus supplying digital information representing the inspected charge level. This sensing circuit permits discrimination and sensing or detection of N different inspected charge levels with a single circuit construction.

Infrared detection system

Abstract: An infrared radiation intruder detection system is disclosed which employs a unique pyroelectric detector array. The array comprises a pyroelectric plastic film having electrodes arranged on opposing surfaces to define a plurality of heat-sensitive capacitors connected in parallel. According to a preferred embodiment, the film of selected detector elements is poled to a polarity opposite that of the other elements to cause internal cancellation of signals due to events which affect an even number of detectors simultaneously.

AC fault current limiting circuit

Abstract: Circuitry for limiting the instantaneous peak current, under fault conditions, of an AC power line, includes a high speed circuit breaker in series with a first capacitor in a main current-carrying branch, which branch is paralleled by two additional branches. According to various embodiments these branches contain various combinations of resistance, capacitance and spark gap elements whereby upon occurrence of the excess fault condition, the high speed circuit breaker opens. Thereafter the voltage buildup across the first series capacitor is sequentially commutated to a second branch having a capacitor and spark gap, with a predetermined arc-over voltage, and subsequently to a third resistive branch. The third branch effectively provides the peak current limiting impedance.

Dielectric Properties of Oil-Impregnated all Polypropylene Film, Power Capacitor Insulation System

Abstract: We have investigated the synthetic oil-impregnated power capacitor insulation system of all polypropylene film dielectrics which is currently used in company products. The results of dielectric measurements in low electric fields can be interpreted by chemical interaction of the polypropylene film with the aromatic synthetic fluid. These investigations' have proved to be quite helpful in the manufacture of power capacitors with superior dielectric properties for service over a wide range of applied voltages.

Charge redistribution circuits

Abstract: A charge redistribution circuit for pulse code modulation encoding suitable for use in apparatus for encoding voice in a companded code to maximize signal-to-noise performance. The companded code is the fifteen segment approximation of the μ255 compression law, wherein each segment contains 16 equal size steps. The circuit includes a single binary weighted capacitor array for the generation of both segment and step boundaries of voice being encoded. Each capacitor in the array has a pair of opposed plates, one plate of each capacitor being commonly coupled together. The circuit further includes a binary comparator having a first input adapted to be coupled to a reference bias potential and a second input coupled to the commonly coupled plates. First switching means connect and disconnect the commonly coupled plates to and from ground potential. Second switching means selectively connect a first common line to an input analog voice signal or to ground potential. Third switching means selectively connect a second common line to a predetermined reference voltage V ref or to a reference voltage V ref/16 (which is 1/16 the predetermined voltage), and selectively couple the first comparator input to ground potential or to the reference bias potential. Fourth switching means, including a switch for each capacitor, selectively couple the other plates of the capacitors to the first or to the second common line. An eight-bit code generator provides a digital eight-bit output upon receipt of a read instruction and control logic for controlling the four switching means, such logic being responsive to the output of the comparator and providing control signals to the generator. Simultaneously, it causes the third switching means to connect the first comparator input to ground when the sampled input signal lies in the upper four segments and it causes the third switching means to connect the first comparator input to a reference bias potential when the sampled input signal lies in the lower four segments.

Active simulation of inductors using current conveyor

Abstract: Some new active networks are proposed for the simulation of grounded and floating inductors, employing only one capacitor, two or three resistors and the second-generation current conveyor as the active element.

Estimation of Higher Frequency Network Equivalent Impedances by Harmonic Analysis Natural Waveforms

Abstract: A digital method of analysing harmonics in a power system has been developed which permits the equivalent network impedance to be estimated by means of the switching of capacitor banks. The method records voltage and current digitally and by data processing computes the amplitude and phase of the harmonics. By comparing results before and after the switching of a capacitor bank on one phase, the equivalent network impedance is estimated at the odd harmonics. Precision of results is acceptable in amplitude but less accurate in phase.

The derivation of switched-capacitor filters from active-RC prototypes

Abstract: A general procedure is given for the design of an active switched-capacitor filter from an actlve-RC model. The process is based on trapezoidal integration. The resulting sampled-data circuit response is related to that of the model through the bilinear z-transformation.

IGFET Integrated circuit memory cell

Abstract: An IGFET integrated circuit memory cell structure utilizing a capacitor with increased charge storage capability, and a method making the same. The capacitor includes a high impurity concentration region having the same conductivity type as the substrate. An island of opposite conductivity type is inset in the region and a conductive field plate overlies the island. The structure also includes a transfer transistor in which the source region is adjacent the capacitor and overlaps the island region therein. Activation of the transistor serves to transfer the charge stored in the capacitor to the drain region where it can be read by external circuitry. In the method, the high concentration region and island in the capacitor are formed by successive ion implantation steps. A subsequent source and drain diffusion causes lateral migration of the conductive portions of the cell to increase the storage capacitance and to insure electrical contact between the island region of the capacitor and the source of the transfer transistor.

A novel variable frequency sinusoidal oscillator using a single current conveyor

Abstract: A new active RC second-order sinusoidal oscillator using a single second generation current conveyor is described. A single grounded resistor adjusts the circuit for oscillation and a single grounded capacitor controls the oscillation frequency without affecting the oscilllation condition.

Differential capacitance measuring circuit

Abstract: The displacement of the diaphragm in a differential pressure sensor of the differential capacitor type produces an output signal substantially linearly related to the displacement. The capacitors are charged in parallel from a constant current source for a fixed period of time and discharged through separate discharge circuits for another fixed period of time. An integrating differential amplifier connected to the two capacitors as they discharge produces an output signal related to the area between the two discharge curves which is substantially linearly related to the extent of displacement of the diaphragm of the differential pressure sensor. The output from the amplifier is used to control the current output from the device.

Power failure light and circuit therefor

Abstract: A power failure light for monitoring a power line and for illumination upon the interruption of power therefrom includes a light bulb, a rechargeable battery, a power supply providing charging current for the battery, a pair of diodes connecting the battery across the power supply, a pair of cascaded transistors connecting the bulb across the battery with the base-emitter junctions of the transistors connected across the diodes to thereby sense the condition of the power line. The base-emitter junctions are reversed biased by the pulsating voltage across the diodes, and a timing network, including a resistor across the power supply and a capacitor across the diodes, maintains the reverse biased condition of the junctions between the voltage pulses.

A new battery charger/discharger converter

Abstract: a new optimum topology dc-todc switching converter is extended to provide bidirectional current flow. The resulting two-quadrant converter can be employed to eliminate the discontinuous curent mode in normal unidirectional applications, but is especially suited for spacecraft battery conditioning as a charge-discharge regulator in place of the conventional separate converters. Implementation of the control features and the battery charge current and voltage limits are discussed.

Active R ladders: High frequency, high order, low sensitivity active R filters without external capacitors

Abstract: Active R filter techniques which make use of the pole of an operational amplifier to produce the state variables without the need for inductors or external capacitors may be employed to simulate all of the elements of both singly and doubly terminated reactance ladders. Although the design techniques are very simple and follow directly from passive synthesis techniques, the resulting filters offer high-order circuits with low sensitivity. However, the primary advantage of these active R filters is the ability to design filters which operate in a considerably higher frequency range than obtainable with standard active RC designs. While still primarily of research interest due to dynamic range problems and temperature sensitivity problems, active R ladders may be adequately compensated to allow many applications in specialized signal processing environments.