Showing papers on "Decoupling capacitor published in 1980"

Liquid crystal display systems

Abstract: A matrix liquid crystal display circuit operates on a level of AC voltage equal to the voltage required for DC drive. The circuit includes a selecting transistor connected to the picture element and a capacitor for each picture element of the matrix. The capacitor in each row connects to a common electrode and the transistor gates in each row connect to a common electrode. The voltage level of the common capacitor electrode is shifted periodically relative to a reference voltage in order to invert the image signal polarity across the picture element and produce an AC drive. Inverted image signals of similar voltage level are alternately sampled.

Power supply for electrostatic apparatus

Abstract: A power supply for electrostatic apparatus provides a high voltage output. The high voltage output is provided by the half wave rectification and filtering of a pulse signal from a secondary winding of a high voltage pulse transformer. The primary winding side of the high voltage pulse transformer is connected in a series loop circuit with a capacitor and a switching device. The capacitor is charged through an input choke connected to a DC supply source. The switching device is triggered after the capacitor is charged such that the capacitor is discharged through the primary winding of the high voltage transformer. The inductive collapse of the high voltage output transformer provides for the turnoff of the switching device and also serves to partially recharge the capacitor. The half wave rectified high voltage output of the power supply is obtained from the recovery pulse of the high voltage pulse transformer. The efficiency of the power supply is improved since ringing in the transformer is dampened due to the extraction of energy from the recovery pulse. The recovery pulse is much higher in amplitude than the firing pulse during which the switching device discharges the capacitor through the primary winding of the pulse transformer. During each repetitive period, the capacitor is charged, the switching device discharges the capacitor, and a short durational recovery pulse is generated. Several independent outputs of the power supply are obtained by providing respective, independent series combinations of transformers and capacitors with the series combinations being connected in parallel across the switching device.

Apparatus for charging a capacitor

Abstract: An NMOS FET circuit for charging a storage capacitor to a voltage higher than the power supply voltage The circuit includes several stages each including a capacitance and FET switches In response to a high level control signal the FET's in effect connect each capacitance between the supply voltage and ground to charge the capacitances Then, in response to a low level control signal the FET's in effect connect the capacitances in series between the supply voltage and the storage capacitor thus transferring a portion of the charges in the capacitances into the storage capacitor The charge placed in the storage capacitor produces a voltage thereacross which is greater than the supply voltage

Power factor control system

Abstract: A control system for automatically adding and subtracting capacitors to and from an electrical supply line for regulating the power factor of the supply line. A three-phase transducer is connected to the supply line and supplies a signal in direct proportion to the VARs of the supply line to a double setpoint meter relay. The meter relay is connected to a pair of timing relays which are selectively energized in response to a capacitor "add" or "subtract" signal from the transducer. If the signal is maintained for a predetermined period of time on one of the timing relays, a motor of a respective "add" or "subtract" cam-actuated switch is activated. The cam switches are programmed to energize or deenergize control relays, which in turn actuate capacitor contactors to add or subtract the next available capacitor. The cam switches are in independent circuits so that the cycling of each capacitor is in a next-one-available cycle, whereby the first capacitor added is the capacitor which was removed the longest from the supply line, and the first capacitor removed is the capacitor which has been energized the longest. This sequence provides uniform usage of all the capacitors and the associated controls.

Electric release device for fire-arms

Abstract: In a battery-operated electric release device for fire-arms having an electronic switch 11 arranged in line between a first capacitor 8 and an electromagnet 9. The battery 3 is connected to the capacitor with no additional mechanically operated switch arranged therebetween. The electronic switch 11 is fired by discharge of a second capacitor 14 through a trigger controlled mechanical switch 15. The second capacitor 14 is provided with a voltage divider 12, 13 so that its charging time is greater than that of the first capacitor 8, whereby the fire arm cannot be prematurely discharged.

Volatile/non-volatile dynamic RAM system

Abstract: A volatile/non-volatile dynamic RAM cell and system in which the cell comprises a storage capacitor for volatilely storing binary information during normal RAM operation; an alterable-threshold storage capacitor for non-volatilely storing the information in non-volatile fashion during power off conditions; and an energy barrier between the two capacitors. Information can be restored to the volatile capacitor either by CCD charge transfer or by charge-pumped operation. The energy barrier facilitates efficient charge pumped restore of information. In one embodiment, the energy barrier is a high concentration substrate surface region having the same conductivity type as the substrate. Alternatively, the alterable-threshold non-volatile capacitor and the energy barrier are provided by a split-gate capacitor which has an alterable threshold non-volatile section (the non-volatile capacitor) and a non-alterable threshold section (the energy barrier).

Methods of and apparatus for generating reference voltages

Abstract: Methods of and apparatus for generating precise reference voltages in a system utilizing a reference voltage V is disclosed including apparatus having a comparator, a voltage-to-current pulse converter having an input coupled to an output terminal of the comparator, a storage capacitor coupled across the output of the converter, and a point of reference potential, a buffer having an input coupled to the output of the converter, means for applying a reference voltage V to one terminal of a first capacitor while the second terminal of the first capacitor is coupled to a point of reference potential, means for decoupling the second terminal from the point of reference potential while the second terminal of the first capacitor remains coupled to an input terminal of a comparator, and means for applying the output of the buffer to a first terminal of the second capacitor wherein a second terminal of the second capacitor is coupled to the input terminal of the comparator. The first capacitor has capacitance value of (2 2n-1 +...+2 1 +2 0 ) m farads. The second capacitor has value of (2 2n-1 +...+2 n ) m farads. "n" is a positive integer, and "m" is a positive constant. In another embodiment, in lieu of the converter, storage capacitor, and buffer, a capacitive attenuator/memory and voltage divider is used. The output of the comparator is stored in the memory, and is applied to a voltage divider having an output coupled to the first terminal of the second capacitor.

Pulse counter type circuit for power-up indication

Abstract: A circuit for counting pulses which may be used, for example, to provide a power on reset signal after power is applied to a circuit, employing charge transfer between two capacitors. The counter charges a first capacitor to a first voltage level between input pulses. During each input pulse, a portion of the charge stored on the first capacitor is transferred to the second capacitor. The voltage across the second capacitor increases with each input pulse. When the voltage on the second capacitor reaches a predetermined threshold level, an output signal is provided by a threshold detector to indicate that a predetermined number of input pulses has been counted. The second capacitor is then discharged in order to reset the pulse counter before beginning another counting cycle.

Monolithically integrable squarewave pulse generator

Abstract: Monolithically integrable squarewave pulse generator having a capacitor acted upon by two bucking constant-current sources, the capacitor having one terminal connected to the two constant-current sources as well as to a non-inverting input of an operational amplifier connected as a Schmitt trigger, and the capacitor having another terminal tied to reference potential, one of the constant-current sources being operative for charging the capacitor, including a third current source connected to the one capacitor terminal connected to the two constant-current sources for aiding the one constant-current source in charging the capacitor, the third current source being responsive to an adjustable potential of the one capacitor terminal; and the Schmitt trigger having an output connected through a decoupling element to signal output of the squarewave pulse generator.

Capacitance measuring apparatus

Abstract: Capacitance measuring apparatus comprises a variable capacitor VC and a reference capacitor FC. Circuits D, ID, are provided for generating a periodic waveform for application directly to the variable capacitor, and in inverted form to the reference capacitor. Switches means SM are operated by control logic CL to connect the two capacitors in sequence to the input of an integrating amplifier IA, the output of which is applied to a comparator CM to which is also applied a reference level. The output of the comparator controls the control logic. Output of the control logic is converted to an indication of the capacitance of the variable capacitor relative to that of the reference capacitor.

Dual channel digitally switched capacitor filter

Abstract: A switched capacitor filter is designed utilizing two parallel switched capacitor charge pumps. These two, parallel charge pumps operate out of phase with each other, thereby allowing charging of a storage capacitor at a rate equal to twice the clock frequency, thereby decreasing incremental voltage steps during the charging of the storage capacitor.

Switched-capacitor transconductance and related building blocks

Abstract: A new element, the switched-capacitor transconductance, is developed and used to construct several other active switched-capacitor building blocks: amplifiers with gain defined by the ratio of capacitors, integrators, inductors, and gyrators. The element is also used to design a switched-capacitor biquad. All reported networks were fabricated with discrete components and tested. Experimental data for the biquad are given.

Microcomputer-controlled circuit tester

Abstract: To test the integrity of a plurality of operating circuits each including a load energizable by an associated driver under the control of a microcomputer, a capacitor charged with unipolar pulsating test voltage is connected to a common terminal of all the operating circuits and concurrently therewith to the input of a trigger element whose threshold equals about half the peak amplitude of that voltage. During one or more brief intervals the microcomputer cuts in the driver of a selected circuit and senses the output voltage of the trigger element to determine whether or not the capacitor is being discharged through that circuit. A display device controlled by the microcomputer indicates the conductive or blocked state of the selected circuit as well as a possible malfunction manifesting itself in a discharge of the capacitor before any driver is turned on.

Improved circuit elements for switched-capacitor ladder filters

Abstract: A new switched-capacitor floating inductance simulation circuit which does not depend on matching of passive elements is presented. A switched-capacitor source termination circuit which functions as a sample-and-hold circuit for a filter is also described.

Automatic gain control circuit with non-negative exponential release

Abstract: An automatic gain control circuit wherein the gain progressively increases in increasingly larger magnitudes. The illustrative embodiment includes an amplifier whose gain is related by a voltage follower to the voltage on a capacitor in a feedback loop. A rectifier develops a signal representing the AGC output level which is compared against a threshold value. A current source, arranged in a further feedback loop with the capacitor and the voltage follower, increases the voltage on the capacitor as a function of that voltage. The second derivative with respect to time of such function is non-negative. To ensure that there exists a voltage on the capacitor upon which the current source can operate, a starting circuit provides a small, non-zero voltage to the capacitor.

Monitoring device for the capacitor battery of a d-c filter circuit

Abstract: A circuit for monitoring the capacitor battery of a filter circuit connected to a transmission line, the capacitor battery consisting of at least two parallel legs, each with a number of series-connected capacitors. A first signal is produced which corresponds to the total alternating current flowing through the capacitor battery. A second signal is produced which corresponds to the difference between the currents flowing through the respective parallel legs of the capacitor battery. The current difference signal is compared with a respective fraction of the total current signal. A fault indicator signal is produced if the difference between the difference current signal and the fractional total current signal exceeds a predetermined threshold value. Further circuitry is provided for correcting drift in the difference current signal, which may be caused by temperature variations or acceptable capacitor failures. Automatic ranging circuitry may be provided in embodiments of the invention in which the total capacitor battery current varies in amplitude over a large range.

Ultrasonic transceiver circuit for level sensing

Abstract: An improved transceiver for use in ultrasonic echo-ranging systems is disclosed together with a system for its use. The transceiver comprises a capacitor to store power received from a central location during an inactive mode, and switching means to disconnect the capacitor from the power supply during the active mode. The capacitor is used both to supply power to an electrostatic transducer to generate an ultrasonic pulse and also to provide a noise free bias voltage to the transducer to enable it to receive the reflected pulse. An amplifier is provided as part of the transceiver so that long transmission lines between transceiver and controller are possible without undue noise. The power supply line can also be used as the signal transmission line and can be provided in a simple two-wire shielded cable, the other wire being used for logic level control signal transmission, thus allowing simplified multiplexing of a plurality of transceivers.

Power factor improving apparatus for power converter

Abstract: The two secondary windings of a transformer the primary winding of which is connected to an AC power supply are each provided with a controlled rectifying circuit. The DC sides of the rectifying circuits are connected in series to supply power to DC motors. One of the secondary windings is detachably connected with a capacitor bank. The capacity of the capacitor bank is selected so that the power factor of the converter can be improved to a satisfactory value when the two rectifying circuits are both controlled to produce output voltages. The capacitor bank becomes connected in response to the fact that the current in the primary winding of a transformer has arrived at a predetermined value.

Storage-capacitor-type EDM power supply

Abstract: A storage-capacitor-type EDM power-supply system wherein the storage capacitor is charged from a DC source to store a predetermined amount of charge thereon under the control of a switch connected between the DC source and the capacitor. The discharge circuit connecting the capacitor with an EDM gap to allow the stored charge to be discharged through the latter also includes a switch which is controlledly rendered conductive by a signal pulse generator which provides a controlled switching signal preprogrammed in a microprocessor such that the capacitor discharge machining current has a predetermined waveform corresponding to the preprogrammed signal. Preferably, the machining current in each capacitor-discharge cycle is in the form of a composite pulse consisting of a series of periodically interrupted pulses of a minimum on-time and off-time.

Efficient high performance envelope detector with controlled decay envelope detection

Abstract: In this controlled decay envelope detector, a capacitor is used to hold the momentary peaks of the input signal. Its only discharge current path is controlled by a circuit which simultaneously monitors the capacitor voltage and the input signal such that the discharge current from the capacitor is proportional to the voltage difference between the capacitor voltage and a conventional exponential RC decay voltage provided in the control circuit. The resulting discharge from the capacitor, in response to a negative-going step input voltage, is an increasing current starting from zero at the time of the transient. The resulting detector output describes an upwardly convexing voltage decay curve which holds its level essentially equal to that of the initial peak input voltage until the next estimated peak input occurs. Only when the next peak input does not come, or is lower than the last one, will the output start dropping at an increasing rate, which provides a correspondingly precise detection of the envelope.

Level detection circuit

Abstract: A level detection circuit comprises a peak value detection and holding circuit having a capacitor which detects and holds the peak value of an input signal by charging the capacitor, an operation control circuit for supplying the input signal to the maximum value detection and holding circuit during a specific time interval to perform maximum value detection and holding operation, a discharge circuit which performs constant current discharge of a charged electric charge in the capacitor of the maximum value detection and holding circuit after the specific time interval, and a detection circuit for detecting the level of the input signal by measuring the time interval between a time point the constant current discharge of the capacitor by the discharge circuit is initiated and a time point the terminal voltage of the capacitor reaches a specific voltage.

R-C Oscillators using plural inverters

Abstract: In an oscillator circuit including a variable capacitor for inverting a pair of inverters oppositely to each other with a time period defined by a resistance value of a resistor and a capacitance of the variable capacitor, an additional capacitor is provided to be biased by an inverter function of an additional inverter in voltage polarity opposite to that of the variable capacitor.

Fast cycling, low power driver for an electromagnetic device

Abstract: A driver for an electromagnetic device, eg a solenoid, is capable of driving the device at a fast cycling rate while dissipating minimal power In response to an actuating signal, a capacitor connected to a high voltage source supplies a high level current to the device for a short time interval until the capacitor is charged Thereafter, a resistor connected to a low voltage source, supplies a low level current to the device, thus minimizing power dissipation In response to the cessation of the actuating signal, a transistor connected in parallel with the capacitor turns on, and acts as a low impedance in parallel with the capacitor, to rapidly discharge the capacitor Once discharged, the capacitor again may supply high level current to the device when the actuating signal is reapplied

Speed control for a rotary machine

Abstract: A first capacitor is discharged with every pulse of a train of pulses of a frequency proportional to the actual speed of a rotary machine under control and is charged up during intervals between these pulses. The voltage of the first capacitor provides a signal to a threshold circuit which operates to provide a second signal whenever the voltage of the first capacitor exceeds a predetermined voltage which may be set in order to set the speed at which the machine is to be controlled. During the presence of the second signal a second capacitor is charged, beginning at a predetermined voltage, preferably zero. The regulating magnitude for the machine to be controlled is derived from the voltage of the second capacitor either directly or indirectly through a controller circuit and a power stage. The circuit is particularly useful for control of the speed of machines that run slowly or can conveniently provide only relatively few speed-indicating pulses per revolution.

Relaxation oscillator including constant current source and latch circuit

Abstract: An oscillator circuit which demonstrates stable operation over a wide range of supply voltages and process variations. A latch circuit is controlled utilizing a timing capacitor. A constant current source is applied alternately to opposite sides of the timing capacitor through a series of switching gates which bootstrap the voltage across the timing capacitor, with the switching gates being controlled by the output of the latch circuit.

An efficient 600 Watt high voltage capacitor multiplier

Abstract: A high voltage dc power supply system is presented that utilizes a “nondissipative” type and therefore highly efficient capacitor multiplier in its output stage. This capacitor multiplier is an integral part of a Schwarz converter employing series resonant circuits for transfer and. control of power. An internal inverter frequency of 30 kHz enhances the power density of the dc converter model of the here presented type. This model provides 16.5 kV for the collector circuit of a traveling wave tube (TWT) for a space borne radar system. The presentation is supported by experimentally acquired data to substantiate the achieved improvement of efficiency. The improved high voltage power supply should lessen the problems associated with high voltage transformers and allow the construction of efficient and reliable “dry type” voltage scaling systems for space, air, terrestrial and marine applications.

Dual charge pump envelope generator

Abstract: A switched capacitor filter is designed utilizing two switched capacitor charge pumps connected in series. These two charge pumps operate with different clock frequencies thereby allowing charging of a storage capacitor at a higher frequency, thereby decreasing incremental voltage steps during the charging of the storage capacitor, resulting in the generation of a smoother exponential voltage rise.

Time-delayed, variable output current limiting means for power amplifiers

Abstract: In a power amplifier including a power output stage connectable to a load having a minimum rated impedance, there is disclosed means for driving the power output stage so as to prevent excess power dissipation thereby caused by loads having impedances lower than the minimum rated impedance. A capacitor is utilized to establish a desired voltage level for an amplification stage which provides the current for the power output stage, the maximum current being determined by the voltage level on the capacitor. Means are provided for charging the capacitor to the desired voltage level, the charging means being incapable of maintaining the desired voltage level on the capacitor in the presence of currents from the amplification stage at or near the maximum desired output current. A portion of the output of the power output stage is fed back to the capacitor to maintain the charge thereon at the desired voltage level; however, this is only operative when the impedance of the load is equal to or greater than the rated minimum impedance so that in the event of lower impedances, the charge on the capacitor is not maintained, reducing the current limit from the amplification stage.

Method for performing a sample and hold function

Abstract: A method of using a sample and hold circuit to obtain a substantially ripple free voltage on the holding capacitor is provided by holding the charge capacitor at a constant voltage during the sampling time and by not routinely charging the charge capacitor to the maximum potential available. This provides a virtually constant voltage from which the holding capacitor can be charged. The level to which the charging capacitor is charged is controlled by an error signal. This error signal is reflected onto the holding capacitor, and is used as an output for the sample and hold circuit.

Circuit for the measurement of surface potential changes by the static capacitor method

Abstract: Circuitry is presented for the measurement of surface potential changes upon adsorption of gases on a metal foil or film by the static capacitor method. The circuit operates in the usual manner applying a backing off potential which opposes the flow of current from the cell comprised of the foil or film and a reference surface. The advantages of the present circuit include simplicity, low cost, fast response time, no moving parts, and the requirement of only one low voltage, dual‐polarity power supply.