Showing papers on "Equivalent circuit published in 1982"

High-speed compact circuits with CMOS

Abstract: Characteristics of various CMOS and NMOS circuit techniques are described, along with the shortcomings of each. Then a new circuit type, the CMOS domino circuit is described. This involves the connection of dynamic CMOS gates in such a way that a single clock edge can be used to turn on all gates in the circuit at once. As a result, complex clocking schemes are not needed and the full inherent speed of the dynamic gate can be utilized. The circuit is most valuable where gates are complex and have high fan-out such as in arithmetic units. Examples are shown of the use of domino circuits in an 8-bit ALU, where simulations indicate a speed advantage of 1.5 to 2 over traditional circuits, and in a 32-bit ALU where a worst case add in 124 ns was projected and a time less than 100 ns was achieved.

Equivalent circuit model for arrays of square loops

Abstract: Square-loop arrays are of interest as frequency selective surfaces. Experimental results for these arrays are presented, and a simple equivalent circuit model is described which predicts the plane-wave transmission characteristics for normal incidence. These elements are a new member of the group of arrays for which simple equivalent circuits are available.

Time-domain skin-effect model for transient analysis of lossy transmission lines

Abstract: A skin-effect equivalent circuit consisting of resistors and inductors is derived from the skin-effect differential equations for simulating the loss of a transmission line. A numerical method is used to analyze the transmission-line differential equations and the skin-effect equivalent circuit, yielding a model which relates the new values of node voltages and line currents to their values at the previous time step. Based on this model, a very simple program was written on a desk-top computer for the transient analysis of lossy trammission lines. Two examples are presented. The first example is an analysis of the step and pulse responses of a 600-m RG-8/U coaxial cable. The computed results show excellent agreement with measured data. The second example studies the current at the end of a 12-in 7-Ω strip line under different loading conditions. Very good agreement has been obtained between the calculated steady-state solution and that obtained by the frequency-domain method.

A complete DC analysis of the series resonant converter

Abstract: The dc-to-dc conversion ratio of the series resonant converter has been determined in the general discontinuous and continuous condection modes. This new analysis gives a complete description of the dc operation of the circuit for any load and for any switching frequency.

A simple formula for the estimation of the capacitance of two-dimensional interconnects in VLSI circuits

Abstract: A simple formula for the estimation of the capacitance of a single interconnection line in VLSI circuits is presented It is shown that the approximation agrees favorably with the results obtained from much more costly two-dimensional simulations The approximation is also simpler and more accurate than other approximations that have been proposed

Improved empirical model for the Jerusalem cross

Abstract: The frequency transmission characteristics of Jerusalem cross grids at oblique angles of incidence are investigated experimentally, and an improved equivalent circuit model for the cross is proposed. Particular attention is given to the properties of the upper resonant frequency band and its application to dichroic reflector antennas. This upper resonance is essentially dipole in nature, changing in frequency as the angle of incidence is varied. It occurs at a higher frequency than expected and is influenced not only by the length of the end caps but also by the mutual reactance between the end caps and the main arm of the cross. An equivalent circuit model for the cross is presented, which more closely matches the observed responses than previous models. Experimental results for a complementary Jerusalem cross grid are also discussed.

A MESFET Variable-Capacitance Model for GaAs Integrated Circuit Simulation

Abstract: A simple MESFET capacitance model which has a clearly explained physical meaning for a wide bias voltage range has been developed for use in simulations of GaAs integrated circuits. In this model, gate-source, gate-drain capacitances are represented by analytical expressions which are classified into three different regions for bias voltages: a before-pinch-off region including the neighborhood of the built-in voltage, an after-pinch-off region, a transition region. 2-dimensional analysis results support the validity of the analytically derived capacitance model. The model is applicable to MESFET's used in integrated circuits that have low donor-thickness product.

Equivalent circuit of an open-ended coaxial line in a lossy dielectric

Abstract: An open-ended coaxial line was used as a sensor in measurement of the permittivity of lossy dielectrics at radio and microwave frequencies. A simplified equivalent circuit related the permittivity to the measured input reflected coefficient. A more complete equivalent circuit is proposed and errors in the permittivity measurements resulting from the simplification are analyzed.

MEDUSA--A Simulator for Modular Circuits

Abstract: A modular circuit is defined as a combination of a certain number of k-modules, which are embedded in a carrier network The modules may represent subcircuits of varying complexity down to single devices Such modular circuits lend themselves to a description by a system of modular equations MEDUSA is a user-oriented simulator which utilizes system modularity during the simulation process itself, ie, for solving the underlying equations This approach enables the consistent numerical solution of both the basic equations of several bipolar devices and the network equations for a circuit environment Hence, MEDUSA in its present state is a merged device-circuit simulator meeting simultaneously the requirements of device and circuit design

Equivalent Circuit Analysis of the Impedance Response of Semiconductor/Electrolyte/Counterelectrode Cells

Abstract: A method to determine the equivalent circuit of a semiconductor/electrolyte/counterelectrode cell is presented. The electrical analog of the phenomenon leading to frequency dependent behavior has been taken to be a resistor in series with a capacitor. The case where a large number of RC elements are present has been determined in the following way. The values of the capacitances and time constants of these elements have been assumed to be distributed exponentially. For this distribution it follows that the equivalent circuit can be represented as a frequency dependent resistor in parallel with a frequency dependent capacitor. Expressions for the frequency dependent resistance and capacitance have been derived. The impedance and admittance responses of a large number of circuits have been simulated. The circuit which best represented an n-Fe/sub 2/O/sub 3/ (1% TiO/sub 2/)/1M NaOH/Pt cell was determined by comparing the simulated responses with the measured responses. 18 refs.

A transmission line model for silicided diffusions: Impact on the performance of VLSI circuits

Abstract: In scaled technologies, performance improvements become increasingly limited by interconnect parasitics. The increased emphasis in the literature on low-resistance replacements for, or supplements to, polysilicon-gate technologies verifies the importance of parasitic limitations. Further, the role of the series source and drain resistance as well as contact resistance in limiting device performance has also been addressed by several authors. This role is further enhanced by the actual much more rapid increase in sheet resistivity with decreasing junction depth than previously assumed by other workers. In fact, it can be anticipated that metallurgical advances, such as silicides, will be required to compensate for the increased sheet resistance of source and drain diffusions. In the present work, a theoretical development of a transmission line model for a totally silicided diffusion is presented. Both the silicide and the diffusion sheet resistivities ρ S and ρ D , and the specific contact resistivity ρ c , are incorporated, unlike earlier models for contact holes only in which ρ S = 0. This model is applied to specific typical MOS structures, including single-section and three-section structures, to calculate the contact resistance contribution to total resistance. These results are used in conjunction with device equations addressing the device and circuit performance of small-geometry MOSFET's. Both n- and p-channel devices are considered as well as various scaling scenarios (constant field, constant voltage, etc.). These results show that for n-channel devices with a gate length of 1 µm, a-factor-of-two increase in circuit performance can be expected when using silicides. However, for p-channel devices, the expected performance gain as a result of using silicides is a factor of ten.

Schaum's outline of theory and problems of basic circuit analysis

Abstract: Basic Concepts Resistance Series and Parallel DC Circuits DC Circuit Analysis DC Equivalent Circuits, Network Theorems, and Bridge Circuits Operational-Amplifier Circuits PSpice DC Circuit Analysis Capacitors and Capacitance Inductors and Inductance PSpice Transient Analysis Sinusoidal Alternating Voltage and Current Complex Algebra and Phasors Basic AC Circuit Analysis, Impedance, and Admittance Mesh, Loop, Nodal, and PSpice Analyses of AC Circuits AC Equivalent Circuits, Network Theorems, and Bridge Circuits Power in AC Circuits Transformers Three-Phase Circuits

Numerical Analysis of Nonlinear Solid-State Device Excitation in Microwave Circuits

Abstract: This paper presents an efficient technique for the numerical determination of voltage and current waveforms when a microwave circuit containing one or more nonlinear elements is excited by a single frequency source. The approach described here is readily applied to microwave networks represented by a large number of equivalent circuit elements, either lumped or distributed. A significant feature of this paper is the detailed investigation of the problem of convergence, using this new technique. The generality of the techniqne is illustrated through its application to studies of the excitation of varactor, Schottky-barrier, and IMPATT diodes in waveguide circuits. In addition, the relationship of this method to the multiple reflection approach is discussed and the convergence mechanism of this reflection technique is studied.

A unified equivalent-circuit approach to the theory of AC and DC hopping conductivity in disordered systems

Abstract: The Miller-Abrahams equivalent circuit is used to motivate an extension of the pair approximation to the AC hopping conductivity sigma ( omega ) of a random system, which embraces the DC limit sigma (0). The theory is simple to develop and readily yields both analytical and numerical results. The formulae obtained reproduce the pair approximation in the low-density limit and give known exact asymptotic results at high densities and high frequencies. The numerical predictions of the theory are compared with data obtained by direct numerical solution of Kirchhoff's equations for random networks. Excellent agreement is obtained for sigma (0) for energy-independent and energy-dependent hopping in 2D and 3D, and for sigma ( omega ) for energy-independent hopping in 3D.

High power factor switching-type battery charger

Abstract: A switching-type charging circuit is described wherein the power factor of the circuit has been optimized. The switching-type charging circuit utilizes a dual loop feedback system to control the input and output current of the circuit. The dual feedback loop system utilizes a sinusoidal voltage reference in conjunction with a pulse width modulation circuit to force the input impedance of the circuit to appear substantially purely resistive.

Analysis and modelling of a coaxial-line/rectangular-waveguide junction

Abstract: The analysis of a commonly used coaxial-line/rectangular-waveguide junction, formed by the coaxial line entering the broad wall of the waveguide, is outlined. The theory is based on a model closely related to the physical situation and does not require the use of empirical factors. Numerical results can be evaluated directly from the theoretical expressions, and aspects of such evaluation are briefly discussed. Extensive comparison of theoretical and experimental results has shown the analysis to be very accurate. An equivalent circuit for the junction, applicable to the case where the TE10 mode is the only propagating waveguide mode, is also reported.

Microwave Wide-Band Model of GaAs Dual Gate MESFET's

Abstract: A multioctave model of GaAs dual gate MESFET's is presented. It consists of 28 frequency independent elements and is valid between 2 and 11 GHz. Dual gate FET's with and without intergate ohmic contact have been considered. The modeling method utilized consists in separate dc and HF characterization and equivalent circuit determination of the active device parts in their actual bias conditions. Thereby, two goals are obtained : a) The topology of the overall model can be derived from well-known simpler, partial ones; and b) the starting values of optimization are precise enough to allow reliable physical solutions.

Electrical derivative characteristics of InGaAsP buried heterostructure lasers

Abstract: Results of a study of the electrical derivative characteristics of InGaAsP buried heterostructure lasers are presented. By considering current‐leakage paths and electrical contact nonlinearities, an equivalent circuit model appropriate to the buried heterostructure laser has been developed. Solutions for the theoretical electrical derivatives of series‐parallel‐reducible networks have been obtained and applied to the equivalent circuit model of the buried heterostructure laser. Comparison of experimentally measured and calculated electrical derivative characteristics provides both qualitative and quantitative information concerning the distribution of current and voltage in buried heterostructure lasers. By combining the techniques of electrical‐derivative measurement and equivalent‐circuit modelling, an improved understanding of the properties of buried heterostructure lasers has been established.

Switching power supply circuit having constant output for a wide range of input voltage

Abstract: A switching power supply is disclosed using a single transistor circuit which provides a constant output voltage for a range of input voltages extending from a nominal 115 volt power supply to a nominal 220/240 volt power supply without requiring a change in the circuit configuration throughout the range of input voltages. The circuit is disclosed in connection with a single transistor forward converter circuit, in which the transformer winding of the converter circuit is provided with a uni-directional clamp to prevent the transformer voltage of a given polarity from exceeding the clamping voltage magnitude. By clamping one polarity of the transformer voltage which is in series with the switching transistor, the maximum peak-to-peak voltage on the transistor is reduced from that which would be produced in the absence of clamping and enables the use of a power MOSFET transistor for the circuit. The clamping circuit is disclosed as a zener clamp and as a circuit including a parallel resistor and capacitor and series diode.

Current Injected Equivalent Circuit Approach to Modeling of Switching DC-DC Converters in Discontinuous Inductor Conduction Mode

Abstract: A new current injected equivalent circuit approach (CIECA) to modeling switching dc-dc converter power stages is developed, which starts with current injected approach, and results in a set of equations which describe completely input and output properties and an equivalent linear circuit model valid at small signal low frequency levels.

Comparative Study of the Losses in Voltage and Current Source Inverter Fed Induction Motors

Abstract: The losses in an induction motor fed from six-step voltage and current source inverters are calculated and a comparison of efficiencies when supplied from these sources is given. The equivalent circuit that includes the effect of space harmonics and corrected for the skin effect in rotor bars is used for the calculation of main and stray copper losses. Stray iron losses due to magnetomotive force (MMF) and permeance harmonics, end leakage and skew leakage are also considered. Losses in the motor when supplied from these sources are also calculated using the modified equivalent circuit having stray and core loss resistors and their efficiencies are compared.

The Equivalent Circuit of the Asymmetrical Series Gap in Microstrip and Suspended Substrate Lines

Abstract: The microwave properties of the series gap in microstrip and suspended substrate lines with unequal widths of the involved lines are described by means of suitable equivalent circuit data. These data have been computed using a rigorous three-dimensional spectral domain hybrid-mode approach developed by Jansen for the numerical characterization of the frequency-dependent scattering parameters of a wide class of strip and slot discontinuities. The results presented extend considerably the range of published gap data. In particular, they show that the stray-susceptances in the equivalent pi-network of the asymmetric series gap exhibit an inductive behavior for the case of tight coupling.

Thermal noise in nonlinear resistive devices and its circuit representation

Abstract: The major developments, since the Nyquist theorem, in the study of thermal noise in linear and nonlinear dissipative devices are briefly summarized. Then the author's recently established theorem for calculating thermal noise in biased, near-equilibrium, nonlinear resistive devices is discussed, and examples of its use are presented. Based on the theorem, an equivalent circuit model for representing the noise in such devices is proposed, and is applied to analyze the behavior of nonlinear resistors in such applications as heat engines and refrigerators.

Time analysis of large-scale circuits containing one-way macromodels

Abstract: In this paper we consider two important fundamental techniques for large-scale circuit analysis. In the first technique, unilateral subcircuit models are considered which we call one-way models. With these models, the independent time integration of the subcircuits can be accomplished. The second technique which is called a time waveform technique is based on the one-way macromodels. In this approach the subcircuits are integrated for the total analysis time in contrast to the conventional incremental time approaches where all circuits are integrated simultaneously by small incremental time steps.

Modeling Latch-Up in CMOS Integrated Circuits

Abstract: Latch-up is a common problem in CMOS integrated circuits. The modeling of latch-up with circuit simulation programs is addressed in this paper. The general features of a lumped element latch-up model are discussed along with a step-by-step approach to the component determination of the model. An example is presented to show the value of the latch-up model in latch-up threshold prediction. Finally, some latch-up control methods are discussed.

A study of capacitance and resistance characteristics of an Al2O3 humidity sensor

Abstract: In this article the fabrication of a humidity sensor employing an Au-poroue Al2O3–Al structure is described. The behaviour of the sensor in both the capacitive and the resistive mode as a function of relative humidity is studied. The effect of frequency on these characteristics is investigated. It is observed that the change in capacitance is small below 30% RH. Above this humidity the capacitance increases rapidly. The dependence of resistance of the sensor on humidity is the reverse of the capacitance dependence. An electrical equivalent circuit model of the sensor based on the structure of the device and the sensing mechanism is developed. The results are interpreted in terms of the model.