Showing papers on "Equivalent circuit published in 1973"

Propagation Modes, Equivalent Circuits, and Characteristic Terminations for Multiconductor Transmission Lines with Inhomogeneous Dielectrics

Abstract: The theory of wave propagation on Iossless multiconductor transmission lines with inhomogeneous dielectrics is developed using matrix analysis. The treatment is concise and complete and has the advantage of identifying propagation modes in a way that permits straightforward physical interpretation. The equivalent circuit for the general line is derived and its application to the solution of wave problems with reflections is demonstrated. Special consideration is given to the problem of characteristically terminating a multiconductor line, i.e., terminating without reflections. The realizability of such a characteristic termination network is discussed, and proofs of realizability are given for the important cases of all lines with homogeneous dielectrics and all three-conductor lines, regardless of dielectric inhomogeneities. Symmetric three-conductor lines are discussed to exemplify the general theory, and an application to the problem of mode conversion on symmetric and asymmetric shielded strip lines is given.

Theory and Design of the Surface Acoustic Wave Multistrip Coupler

Abstract: The multistrip coupler performs the function of a directional coupler for freely propagating surface acoustic waves on a piezoelectrically active substrate. Its operation is analyzed in terms of a transmission line based equivalent circuit. Expressions are obtained for the directionality (transmission and reflection) in terms of the number of coupler strips and the acoustic frequency. Theory and experiment are shown to be in very good agreement. 50-percent metallization is found to give optimum performance; progressive increase in the proportion of the coupler area covered with metal is shown to involve a progressive change from an inline field model to a crossed-field model. Outside a stopband region it is found that a simplified expression for the directionality is valid; this greatly facilitates component design. Design criteria for multistrip components are discussed in terms of substrate and bandwidth requirements. An analysis is included of resistive and capacitative effects on coupling, and problems associated with coupling between dissimilar materials are discussed.

Quasi-Optimum Digital Phase-Locked Loops

Abstract: Quasi-optimum digital phase-locked loops (DPLL) are derived utilizing nonlinear estimation theory. Nonlinear approximations are employed to yield realizable loop structures. Baseband equivalent loop gains are derived, which, under high signal-to-noise ratio conditions may be calculated off line. Additional simplifications are made that permit the application of the Kalman filter algorithms to determine the minimum mean-square error (MSE) loop filter. Consideration is given to sampling rate and implementation requirements. Performance is evaluated by a theoretical analysis and by simulation. Theoretical and simulated results are discussed and a comparison to analog results is made.

Proximity effect bridge and superconducting microcircuitry

Abstract: Techniques have been developed with which it is possible to fabricate superconducting thin‐film structures with a wide variety of electrical and superconducting parameters which show Josephson‐like phenomena. These bridges‐based on the proximity effect‐are made in layered thin‐film ``substrates'' using a large variety of superconducting and nonsuperconducting materials. In this paper we detail the fabrication techniques and the electrical and superconducting characteristics for these proximity effect bridges including a simple low‐frequency (<10 GHz) equivalent circuit based on analysis and experiment which closely describes the quantum phase coherence operation of the bridges in their voltage sustaining state. Extension of these fabrication techniques to entire thin‐film electrical circuits including resistors, capacitors, and inductors with these bridges and leading to an entire superconducting microcircuit technology is discussed.

Dynamic Models of Turbine Generators Derived From Solid Rotor Equivalent Circuits

Abstract: A method is described for determining the structure and coefficients of dynamic models of turbogenerators from detailed equivalent circuits of the d-and q-axes of a solid rotor generator. These models are intended for analyses of power system dynamics in cases where it is desirable to have a very accurate representation of the synchronous machine. The models have been used to study power system hunting or dynamic stability, first swing or transient stability, load rejection overvoltages, resynchronization of cross-compound turbine-generator sets, field current and voltage during out-of-step operation, voltage dip and other phenomena associated with machine operation on power systems. The paper reviews some of the experience obtained in system studies and in comparisons between test results and computer simulations.

Analytical Models for Polyphase Hysteresis Motor

Abstract: Using parallelogram model to the B-H characteristic of the hysteresis material, general expressions for the terminal quantities of a polyphase hysteresis machine are derived. Steady-state equivalent circuit models are developed for both the synchronous and sub-synchronous modes of operation. A comprehensive analysis of rotor parasitic loss components and stator saturation effects is made and these are represented by suitable parameters in the general equivalent circuit models. Reasonably close agreement between the measured and calculated terminal quantities is obtained.

Analytical Models for Distributed Grounding Systems

Abstract: Simple lumped-parameter circuit models for distributed grounding systems have been developed from the truncation of theoretical solutions. The simplest model utilizes two time constants; one for relatively short times and one for relatively long times. The variation of soil conductivity and permittivity with frequency is estimated and taken into account in the determination of the time constants. Estimating curves for the time constants are developed from experience in matching the experimental results of Kawai. Some practical applications of the circuit models are shown in comparing the indicial impedances of different grounding arrangements. The results confirm the fact that, for high resistivity soils, a combination of a concentrated, high-capacitance ground at the tower with a distributed, high-conductance ground of suitable length is superior to either system alone or to a continuous counterpoise.

Equivalent-circuit representation and characteristics of a radiating cylinder driven through a circumferential slot

Abstract: The problem of an infinitely long coaxial cylinder with a single circumferential slot in the sheath is investigated analytically. When the slot width is small compared with the radius of the outer cylinder, an exact integral equation for the aperture field is formulated and subsequently solved by a quasi-static technique. Equivalent circuit representation of the coupling between the outside antenna and the inside coaxial line is obtained in closed form. Due to the highly localized nature of the coupling, the result thus obtained is applicable to finite cylindrical antenna with multiple feed slots.

Digital interface circuit for a random noise generator

Abstract: An interface circuit arrangement between a random noise generator circuit and an output digital logic integrated circuit. The interface circuit includes a digital logic integrated circuit which has impedance levels and voltage levels compatible with that of the output digital logic integrated circuit and which is connected within a closed loop including a differential amplifier which biases the interface digital logic integrated circuit into a symmetrical amplification region substantially midway within its linear range of operation thereby removing a threshold selectivity which otherwise reduces the randomness of the output of the random noise generator.

MOS-device modeling for computer implementation

Abstract: Generalized MOS-device and circuit modeling problems are discussed. Guidelines for comparing MOS-device models, for selecting phenomena to be modeled, for acquiring model parameters, and for implementing the model are established. A voltage variable capacitance subroutine within a four-terminal Q_B field-dependent model is recommended. The importance of accurate data acquisition and model and parameter maintenance is stressed and computer implementation configurations are discussed.

Electrode polarization of ionic conductors

Abstract: A theoretical analysis by Mitoff and Charles of electrode processes for an ionic material is criticized and corrected. These authors introduce three separate capacitances into their equivalent circuit where only one need appear. This frequency‐dependent diffusion‐discharge capacitance is calculated incorrectly by Mitoff and Charles, and earlier relevant work is ignored. Partial blocking small‐signal theory is used to show that Mitoff and Charles's experimental results on three different ionic materials can quite possibly by understood using such an approach, contrary to these authors' expectations.

Equivalent-circuit model for interdigital transducers with varying electrode widths

Abstract: A recently developed bulk-wave equivalent-circuit model that allows the electric fields in a transducer to be arbitrary functions of distance along the direction of acoustic propagation has been adapted for surface-acoustic-wave transducers. Experimental results are presented that confirm the validity of this model.

A Method of Calculating the RI from HVDC Converter Stations

Abstract: Radio Interference ( RI), generated due to the periodic switching of the valves, is an important factor in the design of HVDC converter stations. A method is developed in this paper for calculating the RI level of any given converter station layout. The method consists basically of determining the equivalent circuit for the valve turn-on transients, analyzing the currents as a function of frequency in all elements of the circuit, and finally calculating the RI around the station using the currents obtained above together with data on the physical layout of the station.

A method for the computation of large tolerance effects

Abstract: A method is described for the tolerance analysis of linear circuits with large element variations. It utilizes the adjoint network concept to set up a reduced system of equations, solvable by either Gaussian elimination or iteration. The process appears to be considerably more economical than simple repeated analysis of the circuit, provided that not all circuit elements are toleranced.

Gfi circuit having tuned circuit fault detector

Abstract: A ground fault current interrupter circuit for detecting a ground fault on a hot conductor and on a grounded neutral conductor of a power line. A transformer has two balanced multiturn windings respectively series connected in the two conductors and has a third multi-turn winding excited by an oscillator whose frequency is much higher than the frequency of the power line source. The third winding is connected in a tuned circuit whose change of output signal is sensed to control circuit breaker means in the power line conductors. In the absence of a fault on either line, the two windings in the conductors reflect a balanced, substantially infinite impedance in parallel with the tuned circuit and the signal therein is maximum. A fault on one of the conductors reflects back as a lower impedance to the tuned circuit and the signal therein is reduced in magnitude. The change in signal level is sensed to actuate a circuit breaker. Means are provided to assure that the oscillator frequency and resonant frequency of the tuned circuit are substantially equal, thereby to cancel out the effect of reactive loading on the power line.

Analysis of High Frequency Inverter Circuit

Abstract: A bridge inverter circuit with tuned load is analyzed. A number of nomograms are presented and their use in the choice of circuit components is discussed.

Self-Excited ac High Voltage Generation Using Water Droplets

Abstract: By letting water drops fall through rings into cans, high voltage can be spontaneously generated with no external electrical excitation. Previous work concerning this type of electric influence machine for dc and three-phase ac high voltage generation is extended to include multiphase, multifrequency operation by considering N streams and N cans. A distributed equivalent circuit representation is used to calculate the natural frequencies of the system, where it is found that many overstable modes are present. Experimental observations with up to five cans are presented. This device can serve as a model for phenomena concerned with atmospheric electricity.

Frequency Response of Quarter-Wave Coupled Reciprocal Stripline Junctions

Abstract: The frequency response of quarter-wave coupled reciprocal 3-port symmetrical junctions for which the reference eigennetwork appears as a short circuit at the reference terminals is presented. The equivalent circuit of such reciprocal junctions is constructed in terms of the reciprocal parts of the split admittance eigenvalues of the ideal 3-port circulator. Since the two circuits are related, the element values selected for the matching networks are the ones which apply to an ideal circulator with an overall Chebyshev response. This is done for n=1, 2, and 3. An important conclusion of this paper is that the design of wideband circulators is closely related to the design of wideband reciprocal 3-port junctions. The paper includes experimental results obtained on a stripline device in its magnetized and demagnetized states.

Control of power converters having a parallel resonant commutation circuit

Abstract: In a variable operating frequency inverter or other converter with a parallel resonant commutation circuit, the frequency changes with the load to control the reactive power available for commutation of the thyristors or other controlled power devices. A constant turn-off time control circuit automatically adjusts the operating frequency so that the reactive power for commutation is optimum and reliability is improved. The control circuit and method utilizes sensed instantaneous power circuit parameters from which the future state of the commutating capacitor voltage can be predicted, and a computation circuit for determining the timing of firing signals to provide an approximately constant turn-off time for a conducting device.

Application of the transmission line equivalent circuit model to the analysis of the PN junction admittance under d.c. bias

Abstract: Exact non-equilibrium one-energy-level numerical solutions of the admittance of a p+n junction are obtained from the nonuniform transmission line equivalent circuit model. Capacitance and conductance curves for equilibrium and reverse-biased gold-doped silicon diode are calculated using experimental values of emission and capture rates. Comparisons between theoretical and experimental frequency dependences of the admittance using new experimental capture rates show good agreements over a wide range of reverse bias.

Series equivalent circuit representation of SiO2Si interface and oxide trap states

Abstract: The small-signal frequency response of silicon dioxide-silicon interface and oxide trap states has been investigated and interpreted using a series R-C equivalent circuit model instead of the commonly used parallel R-C equivalent circuit model. It is shown that the series equivalent circuit model is advantageous in extracting the time constants of the oxide traps located in the silicon dioxide layer from experimental data and allows a determination of the spatial extension of the oxide traps. Comparisons of a two-step model, consisting of the Shockley-Read-Hall transition between the band and the interface states and the elastic tunneling transition between the interface and oxide trap states, with experimental data are given to illustrate the range of experimental data required to evaluate an unique set of tunneling and SRH parameters.

Mosfet dynamic circuit

Abstract: An integrated complementary MOS transistor circuit is used to divide an input frequency by a factor or two, and similar circuits may be used as counters or shift registers. The circuit is dynamic, low in power consumption, and is based upon one or more inverters which operate in the pulsed power mode.

Large-Signal Equivalent Circuit for IMPATT-Diode Characterization and Its Application to Amplifiers

Abstract: A frequency-independent lumped equivalent circuit is proposed for characterizing the large-signal behavior of IMPATT diodes. It has five elements including a negative resistance, two of which are quadratic functions of the single-frequency RF voltage across the device. It is used for computer-aided analysis and the design of reflection-type negative-resistance amplifiers employing IMPATT diodes. The frequency response of the amplifier is calculated for different input power levels and the nature of the results is found to be in agreement with published experimental results.

Analysis and modeling of a family of two-transistor parallel inverters

Abstract: A family of five static dc-to-square-wave inverters, each employing a square-loop magnetic core in conjunction with two switching transistors, is analyzed using piecewise linear models for the nonlinear characteristics of the transistors, diodes, and saturable-core devices. Four of the inverters are analyzed in detail for the first time. These analyses show that, by proper choice of a frame of reference, each of the five quite differently appearing inverter circuits can be described by a common equivalent circuit. This equivalent circuit consists of a five-segment nonlinear resistor, a nonlinear saturable reactor, and a linear capacitor. Thus, by proper interpretation and identification of the parameters in the different circuits, the results of a detailed solution for one of the inverter circuits provide similar information and insight into the local and global behavior of each inverter in the family.

J-Band Transferred-Electron Oscillators

Abstract: An equivalent circuit for a J-band transferred-electron oscillator containing lumped and distributed elements is proposed. Using element values obtained independently, the equivalent circuit is shown to have broad-band applicability and is capable of explaining, in a strictly quantitative fashion, frequency saturation and the loss or absence of circuit-controlled oscillation. It is shown that the S4 type of encapsulation places severe constraints on the mounting structure and is not ideally suited to the J-band waveguide oscillator for optimum power-frequency characteristics over a broad band. The analysis of the full equivalent circuit given does, however, permit analytic solutions for important oscillator design parameters such as mounting post diameter, which enables simple post-mounted J-band oscillators that are free from frequency saturation and loss of circuit-controlled oscillation in the band to be easily designed.

New approach to general theory of electrical machines using magnetic equivalent circuits

Abstract: First, the nature of equivalent circuits and the alternative electric or magnetic equivalents for any electromagnetic system are examined. In the remaining Sections, steady-state and symmetrical sudden short-circuit conditons are analysed for the3-phase synchronous, the 3-phase induction and the compounded d.c. machine, using the magnetic-equivalent representation. Results are obtained more easily than by the conventional procedure. Also, since the method of analysis is the same for each of the cases considered, results obtained for one type of machine can often be applied to another and the approach is truly general.