Showing papers on "Negative impedance converter published in 1975"

Nonideal negative resistors and capacitors using an operational amplifier

Abstract: Negative impedance converters (NIC's) may be used to realize negative driving-point impedances. The effect of the nonideal characteristics of the operational amplifier such as finite frequencydependent gain and output impedance on the performance of the negative impedances is analyzed. Detailed equivalent circuits showing the additional positive or negative inductive impedances due to the nonideal characteristics are given for negative resistance and negative capacitance realizations, and their relative performances are compared. The experimental results confirm the validity of the equivalent circuits. The effect of the slew rate of the operational amplifier on the maximum signal-handling capability (SHC) of the negative impedances at high frequencies is studied. Practical design considerations for achieving wider bandwidth as well as improved SHC are discussed.

Negative impedance network

Abstract: A negative impedance network includes a pair of network terminals, with one terminal connected to the base of an emitter-follower transistor. A current mirror includes one current path connected to supply a first current to a fixed impedance means through the collector-emitter circuit of the transistor and a second current path supplying a second current to the one network terminal in fixed ratio to the first current, such that an effective negative impedance is presented in parallel to an external circuit connected across the network terminals.

Bias circuit for FET

Abstract: A bias circuit particularly adapted for use with a field effect transistor whereby the drain bias current of the field effect transistor is maintained constant in the event of fluctuations in the operating voltage applied to the field effect transistor by a power supply. The bias circuit changes the gate bias voltage applied to the FET as a function of the fluctuations in the operating voltage to thereby restore the drain bias current to a constant value. A variable impedance is included in the bias circuit, the variable impedance being voltage dependent such that its impedance varies as the voltage applied thereto varies in accordance with a hyperbolic relation. The voltage applied to the variable impedance is derived from, and thus includes the fluctuations in, the operating voltage. The hyperbolic relation between the impedance and the voltage applied to the variable impedance effectively matches the relation between the pinch-off voltage VP and the amplification constant μ of the FET.

AC motor control system - has voltage and frequency variable converter employing several triodes

Abstract: The control system has a switching control network which supplies the control signals for each of the triodes and an oscillator for voltage regulation, for control of the switching phase of the diodes via the latter network. The output voltage of the converter is supplied to a voltage monitor with a current monitor for the output current from the converter, and a phase monitor detects the phase difference between the output voltage signal for controlling the frequency of the voltage regulating oscillator in conjunction with a signal denoting the required power factor.

Modulator and clamper for variable impedance load

Abstract: A transformerless Blumlein type circuit is combined with a novel clamper circuit for driving a cold cathode electron beam gun for a CO 2 laser where the E-beam gun has resistance essentially infinite at the leading end of a driving pulse and has several ohms resistance at the end of the driving pulse. At the leading end of a driving pulse the voltage output of the Blumlein circuit is twice the rated load voltage since the load as infinite impedance. The clamper circuit limits the pulse voltage across the load to its rated voltage and the excess power from the Blumlein circuit over that required by the load is dissipated in the clamper circuit. The clamper circuit as variable impedance that is approximately the inverse of the load impedance during a driving pulse so that the Blumlein circuit looks into an approximately constant impedance equal to its impedance.

A New Voltage to Frequency Converter

Abstract: The technique for improving the linearity between the input voltage and the frequency of oscillation is described. This improvement is accomplished by adding a control circuit to Concentional voltage-to-frequency converters. From the experimental results, the linearity of this converter was about 0.15 percent at the frequency of 1 MHz.

Alternating current control circuits

Abstract: A novel circuit is provided for controlling an alternating current supplied to a load which includes a variable impedance element in the form of a low emitter concentration transistor which is bidirectional, and which has a high gain. The impedance of the variable impedance element to the flow of current therethrough is substantially the same in either direction of current flow.

Bipolar regulated high voltage power supply

Abstract: Two sources of current are applied to a load. One source supplies a constant current which is at least equal to the maximum current to be supplied to the load in one polarity. The second source is in opposition to the first source and is capable of being controlled from zero to a value at least double the value of the constant current. A voltage feedback circuit in combination with a bipolar control signal provides a bipolar voltage across the load having maximum positive and negative voltage excursions equal to the control signal times the feedback circuit gain and current in either direction having a maximum value substantially equal to the constant current value. In this manner a high voltage regulated bipolar voltage can be controlled across a load using one controlled unipolar device while providing class A operation, that is, without cross-over distortion. An important feature of the invention is the positive and negative limiting of both load voltage and load current.

Voltage comparator and indicating circuit

Abstract: A device including a voltage indicator circuit has the capability of indicating positive, neutral and negative voltages with respect to a reference voltage. Three indicator circuits are mounted on a single substrate. Each indicator circuit energizes a respective light emitting diode to indicate whether a voltage applied to a probe is positive, neutral or negative with respect to a reference voltage. The reference voltage is applied to a ground or reference terminal on the circuit. An alternating voltage is indicated by rendering effective all three light-emitting diodes. An open circuit can be ascertained by the absence of a positive signal from all the diodes.

Alternating current energy converter

Abstract: An alternating current energy converter comprising a direct energy converter, the internal resistance of which is so connected into an alternating current circuit that current flows as rectified current therethrough and the reactance of the alternating current circuit is greater than the resistance of the direct energy converter.

Sewing machine position and speed sensing system

Abstract: Logic circuit device and frequency voltage converter connected to the impulse preparation device. A gate being interposed between voltage converter and the impulse preparation device. Comparator connected to the converter which compares its output to an adjustable reference voltage.

Single-ended/push-pull converter

Abstract: A single-ended/push-pull converter with an input emitter-follower transistor having a d.c. blocking emitter impedance and a collector impedance. The signal voltage across the collector impedance produces a signal current of opposite phase in a second emitter follower transistor having an input impedance which equals the collector impedance of the first transistor. The input circuit of a current mirror is included in the emitter circuit of the second emitter follower transistor and the output circuit is connected in parallel with the d.c. blocking impedance to keep the collector currents in the two emitter followers equal and constant.

Network having a transformer-coupled open-circuit stable negative impedance and a short-circuit stable positive impedance

Abstract: A network has a transformer coupled open-circuit stable negative impedance. A positive impedance is included in the network as a shunt impedance, so as to thereby render the network both open-circuit stable as well as short-circuit stable.

Variable control current generator arrangement

Abstract: Variable current generator arrangement for controlling the position of remote load components allowing replacement of a main control current generator by an auxiliary control current generator. The main control current generator is a current injector with high output impedance. The auxiliary control current generator is a voltage follower with low output impedance. For performing switchover, a switch means allows the voltage across the load component to be applied to an analog store means and the voltage in said store means to be applied to the voltage follower.

High voltage supply circuits

Abstract: High voltage supply circuits for television apparatus. The current in a primary circuit of a transformer is determined by a transistor the impedance of which is controlled by negative feedback from a high voltage output coupled to the secondary circuit of the transformer. Current pulses in the primary are produced by switching another transistor in the primary circuit at television line frequency. The circuit can be employed to supply a dynode resistor chain of a photomultiplier in a flying spot colour television transmitter, the luminance signal being averaged by a long time constant integrating circuit and summed with the negative feedback to provide a further feedback control compensating for variation in the average density of film being scanned.

Design of a Negative-Impedance Converter and Its Application for a TV Deflection Circuit

Abstract: Most horizontal deflection circuits used in TV cameras or TV receivers are deflection circuits operated by the switching function of transistors. This type of circuit is well known as an efficient deflection system having less power consumption, however, because there is a resistance existing in the deflection coil or within the circuit, it has a defect in that distortion is liable to occur in the deflection current. In order to improve the linearity of this deflection current, various methods were offered in the past, however, nothing definite has been found to solve this problem.