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Showing papers on "Negative impedance converter published in 1972"


Journal ArticleDOI
TL;DR: In this article, a six-port coupler is described with four side arms whose outputs are proportional to the voltage, current, incident voltage wave, and reflected voltage wave at some desired measurement plane in the transmission line.
Abstract: A six-port coupler is described having four side arms whose outputs are proportional to the voltage, current, incident voltage wave, and reflected voltage wave at some desired measurement plane in the transmission line. The phase relationship between the outputs is the same as between corresponding quantities at the measurement plane. Complex impedance and phase angle as well as voltage, current, and power can be obtained from simple power or voltage magnitude measurements at the four side arms. A vector voltmeter used with this six-port becomes a direct reading vector impedance meter, admittance meter, or reflection coefficient meter.

148 citations


Patent
31 Jul 1972
TL;DR: In this paper, a dc-to-dc converter provided with dualmode current and voltage regulation and a "soft" start characteristic in which a digital-type feedback control is obtained based upon the relative priority of the arrival of the respective feedback pulses at the driving circuit for the converter transistors.
Abstract: There is disclosed a dc-to-dc converter provided with dual-mode current and voltage regulation and a "soft" start characteristic in which a digital-type feedback control is obtained based upon the relative priority of the arrival of the respective feedback pulses at the driving circuit for the converter transistors. In addition, a shut-down circuit checks both of two redundant feedback circuits for the absence of feedback pulses for a prescribed time before triggering shutdown. Either of the two redundant feedback circuits is individually capable of regulating the output voltage or the output current if the output load is balanced. With a high impedance unbalanced load, the voltage regulator on the output lead that tends to experience high voltage takes control and limits the maximum output voltage.

32 citations


Patent
14 Apr 1972
TL;DR: In this article, an automatic noise reduction system has a signal amplifier, a resistor as a first impedance circuit and a second impedance circuit which comprises resistors, capacitor and a variable resistance element.
Abstract: An automatic noise reduction system has a signal amplifier, a resistor as a first impedance circuit and a second impedance circuit which comprises resistors, capacitor and a variable resistance element. The frequency response of the second impedance circuit changes according to the resistance value of the variable resistance element and that resistance value is changed by a control circuit. In recording, the resistor constituting the first impedance circuit is connected to the input side of the signal amplifier and the second impedance circuit is connected to the negative feedback loop of the signal amplifier, and the control means provides a D.C. voltage in response to the input signal, so that the signal to be recorded is emphasized. In reproducing, the connection is reversed and the control means provides a D.C. voltage in response to the output signal, so that the reproduced signal is modified with characteristics complementary to the emphasized characteristics and provided with the same wave form as that of the original signal with reduced record medium noises.

16 citations


Patent
Sauer Helmut Dipl Ing1
18 Jan 1972
TL;DR: In this article, two three-phase thyristor inverters, connected in parallel at the input side, are connected together via voltage divider chokes, providing the three outputs of the converter.
Abstract: A circuit for converting a DC voltage or a three-phase voltage of variable or constant frequency into a three-phase voltage of a constant other frequency utilizes an intermediate circuit frequency converter. The converter comprises two three-phase thyristor inverters, connected in parallel at the input side. The three-phase outputs of the one three-phase thyristor inverters are connected together via voltage divider chokes. The taps of the voltage divider chokes provide the three outputs of the converter.

16 citations


Patent
05 May 1972
TL;DR: A synchronizing and transfer system enabling a fully loaded induction motor to be switched from or to a variable frequency converter having a quasi-square wave voltage, to or from a line having a sine wave voltage is described in this paper.
Abstract: A synchronizing and transfer system enabling a fully loaded induction motor to be switched from or to a variable frequency converter having a quasi-square wave voltage, to or from a line having a sine wave voltage. Upon the motor to be transferred reaching a full-speed condition, the system senses the frequency and phase angle difference between the converter output and line and acts upon the converter frequency to decrease the difference. When the frequency and phase angle differences are within preset limits, load transfer switching is initiated. During the course of load transfer, an inductive impedance is transiently inserted in series with each phase of the converter output for a period of parallel feed, the impedance acting to prevent excessive cross currents from damaging the converter.

15 citations


Patent
19 Dec 1972
TL;DR: In this paper, a gain control circuit includes a first branch having an impedance which varies with the externally applied AGC signal and a second branch with an impedance varying with the current flow therethrough and which is connected to ground through an AC bypass.
Abstract: A gain controlled amplifier circuit in which the amplifying element, such as a transistor, has its emitter-collector circuit connected to a gain control circuit which supplies a constant operating current and changes its AC impedance in accordance with an AGC signal. The gain control circuit includes a first branch having an impedance which varies with the externally applied AGC signal and a second branch having an impedance which varies with the current flow therethrough and which is connected to ground through an AC bypass. These two branches are connected in parallel to a constant current source so that the impedance of the first branch controls the current flow in the second branch and thereby its impedance.

11 citations


Patent
01 Mar 1972
TL;DR: In this paper, a temperature measuring voltage to current converter including a temperatureresponsive resistance bridge was presented. But the converter was not used for temperature indication. But it was used in a wide variety of applications not limited to temperature indication and temperature controlling.
Abstract: A temperature measuring voltage to current converter including a temperature-responsive resistance bridge with an output connected to the input of an amplifier having an output connected to the resistance bridge wherein the resultant change of the output current of the amplifier is directly proportional to any change of its input voltage and independent of its load resistance so long as the amplifier is operating within its capabilities. The converter may be used in a wide variety of applications not limited to temperature indication. The bridge is used both in temperature indication and temperature controlling. The circuit of the converter needs little power and current. The use of a unique circuit construction makes it possible to produce a meter range of the precise magnitude desired. The use of the same unique circuit construction makes possible high sensitivity and the determination and adjustment of the point at which most accuracy and linearity exists. Meter overvoltage protection is also provided.

11 citations


Patent
12 Sep 1972
TL;DR: In this article, a threshold circuit for connection between the terminals of a power-supply and a load, particularly a tone-ringer for use in a station-set of a telephone or like data-transmission system, was proposed.
Abstract: The present invention relates to a threshold circuit for connection between the terminals of a power-supply and a load - particularly a tone-ringer for use in a station-set of a telephone or like data-transmission system. The circuit is used to switch between a dummy load and a main load - such as a tone-ringer - wherein the dummy load normally takes lesser current draw than the main load. Therefore, for a given power-supply impedance, the voltage drop across the power-supply lines will increase and in conventional circuits this reduces the voltage level below the threshold, causing parasitic oscillation. The present invention eliminates this problem by providing hysteresis in the threshold voltage by use of a positive feedback network, so that the dummy load will not be switched in again until the power-supply voltage is considerably less than the original threshold voltage level.

7 citations


Patent
07 Dec 1972
TL;DR: In this article, a voltage generator operating through a series impedance into two transmission lines of substantially the same characteristic impedance is used to interrupt a voltage sensitive device such as a Kerr cell or a Pockels cell by a sharp, brief, square pulse.
Abstract: A steady voltage applied to a voltage sensitive device such as a Kerr cell or a Pockels cell is caused to be interrupted by a sharp, brief, square pulse, during which the applied voltage is zero, by means of a single d.c. voltage generator operating through a series impedance into two transmission lines of substantially the same characteristic impedance. One line is connected between the generator (i.e., its series impedance) and the load, which is a high impedance, and the other line has one end connected to the generator (i.e., its series impedance) over a switch and its other end connected to a high impedance which acts as an effective open circuit. Closing the switch produces a series of substantially zero voltage intervals across the load, the period being determined by the combined length of the lines and the duty cycle by their relative length, but after the first few pulses the dissipation in the transmission lines and their terminations prevents the voltage from dropping all the way to zero, but for laser triggering only the first pulse is normally needed and the subsequent ones cause no disturbance.

7 citations


Patent
19 Jun 1972
TL;DR: In this paper, a single-pole double-throw switch with two transistors of opposite conductivity types is used to enable direct current to flow in one direction through the load impedance and the conductive transistor.
Abstract: One terminal of a load impedance is connected to the collectors of two transistors of opposite conductivity type. Their emitters are connected to positive and negative power supply terminals to receive direct current, and the emitter-collector circuits of the two transistors are in current-carrying polarity with respect to the direct current terminals. The bases of the two transistors are connected to the arm of a single-pole-double-throw switch. The fixed contacts of the switch are connected to the positive and negative power supply terminals so that in one position the base of one transistor is biased to conductivity to allow current to flow in one direction through the load impedance and the conductive transistor. When the switch is in the opposite position the other transistor is conductive and current can flow in the opposite direction through the latter transistor and the load impedance.

7 citations


Patent
31 Aug 1972
TL;DR: In this paper, a conference circuit for multiple telephone subscribers including a plurality of input ports for connection to a common transmission line, means for selectively connecting each of the input ports to the transmission line.
Abstract: A conference circuit for multiple telephone subscribers including a plurality of input ports for connection to a common transmission line, means for selectively connecting each of the input ports to the transmission line, means for connecting an impedance associated with each of the input ports to the transmission line when the input port is disconnected from the transmission line and for disconnecting the impedance when the associated input port is connected to the transmission line, a shunt type negative impedance converter including a pair of operational amplifiers connected in a modified push-pull configuration to the transmission line, each amplifier having inverting and non-inverting input terminals and an output terminal, negative feedback means coupled from the output terminal to the inverting input terminal, and positive feedback means coupled from the output terminal to the non-inverting terminal, the positive feedback means including an impedance sufficient to prevent oscillation of the operational amplifier regardless of the number of input ports connected to the transmission line.

Patent
C Lai1
26 Oct 1972
TL;DR: In this paper, an analog-to-pulse-width converter (A2PWC) is proposed, where an analog voltage representing the oil pressure of an internal combustion engine is applied at the input of the circuit to charge the capacitor of the multivibrator to the voltage level of the analog voltage.
Abstract: An analog to pulse width converter circuit includes a monostable multivibrator. The circuit is maintained in a first stable state by a constant current source. An analog voltage representing, for example, the oil pressure of an internal combustion engine is applied at the input of the circuit to charge the capacitor of the multivibrator to the voltage level of the analog voltage. A sample oscillator applying pulses periodically to the circuit triggers the latter to operation in a second, active state, whereby an output is provided from the circuit. Upon operation to the active state, the constant current source charges the capacitor in the opposite direction; the reverse charging time being determined by the original charge on the capacitor at the time of application of the trigger pulse. The duration of the circuit output is thus equal to the reverse charging time and directly related to the voltage level of the analog voltage. Additional circuitry including a clock oscillator, AND gate and pulse converter may be employed in conjunction with the analog to pulse width converter circuit to provide an analog to digital converter.

Patent
16 Aug 1972
TL;DR: In this article, a resonant type current regulator with a controlled inductive impedance in series or in shunt connection with the current path is presented, where a control is provided to vary the impedance value of the inductive resistor in response to load current deviating from a reference value in a manner to stabilize the load current.
Abstract: A resonant type current regulator in which a controlled inductive impedance is provided in series or in shunt connection with the current path. A control is provided to vary the impedance value of the inductive impedance in response to the load current deviating from a reference value in a manner to stabilize the load current. An antiparallel arrangement of a pair of controlled semiconductor devices can be used for the controlled inductive impedance their control gates receiving control signals at times in each current half period which depend on the magnitude of the current deviation.

Patent
30 May 1972
TL;DR: In this paper, a motor circuit is connected across the output of the subtracting amplifier, and a feedback arrangement, connected with the motor and with the other input of the amplifier, applies to the latter at least part of the voltage drop across the motor.
Abstract: A regulating arrangement comprises a subtracting amplifier having an output and two inputs, and producing at the output a voltage equal to a first factor times the voltage at one of the inputs minus a second factor times the voltage at the other of the inputs. A motor circuit is connected across the output of the subtracting amplifier. The motor circuit includes a motor connected with an impedance. The impedance is connected with the motor and with the output of the subtracting amplifier and enforces a voltage drop across the motor of magnitude differing from the voltage magnitude across the amplifier output by at least the magnitude of the voltage drop across the impedance. The voltage drop across the motor increases in magnitude as the motor current supplying energy to the motor decreases. Accordingly, the voltage drop across the motor tends to increase as the motor speed increases. A command unit applies to one of the inputs of the subtracting amplifier a voltage effecting desired motion of the motor. A feedback arrangement, connected with the motor and with the other input of the amplifier, applies to the latter at least part of the voltage drop across the motor.

Patent
10 Jul 1972
TL;DR: In this article, the authors present a method for measuring an unknown impedance in the presence of extraneous signals by injecting into the impedance to be measured an oscillating current signal, which may be modulated, generating in the unknown impedance a voltage signal, applying the generated signal and any extraneous signal present in the circuit under test to a switch which is keyed by the injected current pulse so as to conduct only during the times the injected pulse has a given polarity.
Abstract: Method and apparatus for measuring an unknown impedance in the presence of extraneous signals by injecting into the impedance to be measured an oscillating current signal, which may be modulated, generating in the unknown impedance an oscillating voltage signal, applying the generated signal and any extraneous signals present in the circuit under test to a switch which is keyed by the injected current pulse so as to conduct only during the times the injected pulse has a given polarity, thereby producing through the switch a signal of a pulsating nature, and filtering the pulsating signal to produce a DC voltage, the magnitude of which is a measure of the unknown impedance.

Patent
29 Jun 1972
TL;DR: In this article, a precision electronic tuning device for tuning a musical instrument, having an audio pre-amplifier, a frequency to voltage converter, a D.C. attenuator and a differential voltmeter, was presented.
Abstract: A precision electronic tuning device for tuning a musical instrument, having an audio pre-amplifier, a frequency to voltage converter, a D.C. attenuator and a differential voltmeter, the differential voltmeter connected between the outputs of the D.C. attenuator and the frequency to voltage converter as a null indicator to indicate the voltage difference between the two. The audio pre-amplifier amplifies the signal from the musical instrument and its output is connected to the input of the frequency to voltage converter. The frequency to voltage converter changes the amplified frequency to voltage proportionally.

Patent
G Cutsogeorge1
20 Apr 1972
TL;DR: In this paper, a circuit for converting an input voltage, the polarity and magnitude of which may vary, into two sets of pulses, one for each polarity of input voltage.
Abstract: A circuit for converting an input voltage, the polarity and magnitude of which may vary, into two sets of pulses, one for each polarity of input voltage. The width of each pulse is related to the magnitude of the input voltage. The circuit includes a feedback arrangement to enhance the accuracy of the circuit.

Journal ArticleDOI
TL;DR: It is shown that the observed stability behavior can be systematically derived without explicitly including the device parasitics, and the identity of the negative impedance converter ports as opencircuit stable or closed-circuits stable becomes systematically available.
Abstract: Beginning with fundamental observations, the concept of port orientation is introduced providing a classification of networks as oriented or nonoriented. By incorporating the orientation property in the network mathematical description, a feedback model equivalent to active networks is derived. In this way the stability criteria of feedback systems can be directly applied to active networks. The feedback model is applied to the stability study of negative resistance 1-ports, negative impedance converters, and negative impedance inverters. It is shown that the observed stability behavior can be systematically derived without explicitly including the device parasitics. Accordingly, the identity of the negative impedance converter ports as opencircuit stable or closed-circuit stable becomes systematically available.

Patent
23 Aug 1972
TL;DR: A semiconductor impedance conversion circuit is a circuit which employs a semiconductor circuit consisting of two transistors, three impedance elements or circuits, a DC voltage source and a DC current source and in which a negative impedance conversion function is obtained between two terminals as mentioned in this paper.
Abstract: A semiconductor impedance conversion circuit which employs a semiconductor circuit consisting of two transistors, three impedance elements or circuits, a DC voltage source and a DC current source and in which a negative impedance conversion function is obtained between two terminals. An oscillator employing the above semiconductor impedance conversion circuit and an oscillating capacitor.

Patent
23 Aug 1972
TL;DR: A semiconductor impedance conversion circuit is a circuit which employs a semiconductor circuit consisting of two transistors, four inpedance elements or circuits, a DC voltage source and a DC current source and in which a negative impedance conversion function and a gyrator function are obtained between two terminals as discussed by the authors.
Abstract: A semiconductor impedance conversion circuit which employs a semiconductor circuit consisting of two transistors, four inpedance elements or circuits, a DC voltage source and a DC current source and in which a negative impedance conversion function and a gyrator function are obtained between two terminals. An oscillator employing the above semiconductor impedance conversion circuit and an oscillating capacitor. A frequency modulator employing the above semiconductor impedance conversion circuit, an oscillating capacitor and a modulating signal source.