Linear Equivalent Circuit Research Articles

Analysis and Modeling of a Voltage Doubler Rectifier Fed by a Piezoelectric Transformer

Piezoelectric transformers (PZT) can be used advantageously in high output voltage dc-dc converters. In such applications the output section includes a voltage doubling rectification scheme to help increase the output voltage. This topology was modeled and analyzed by considering the expected voltage and current waveforms under the first harmonics approximation. The results were then used to build a linear ac equivalent circuit that emulates the ac-dc stage. The proposed model was verified against simulation and experimental results.

Linear Equivalent Circuit and Current Source for I/O (LECCS-I/O) Modeling of IC Power Current for EMI Simulation

In this paper, we describe how we modeled EMI noise from the power-pin current of an LSI that has two ports: a power-ground port and a driver output port. We called this the “Linear Equivalent Circuit and Current Source for I/O (LECCS-I/O) ” model, and have evaluated it using the measured power current and power-ground impedance of a small-scale IC (74LVC04) under various combinations of loading capacitances and decoupling inductances. Results showed that up to 500MHz, the LECCS-I/O model was able to predict peak and valley frequencies of the power current spectra within an error of 2.5MHz, and where the peak current error was less than 5dB. The application range of the LECCS-I/O model was valid where the shortest data duration was longer than twice the decay time constant of the power current under-damping waveform.

Physics-Based Correction of Extracted Conductance Parameters of Nonlinear Microwave Semiconductor Devices

Nonlinear models of microwave semiconductor devices are usually evaluated from small-signal high-frequency measurements of differential parameters, performed at many bias points. A linear equivalent circuit is extracted at each bias point, and this is used to construct the nonlinear model. This procedure does not take into account the effects of slow phenomena as heating of the semiconductor or trapping/detrapping of carriers, produced by biasing. Thus, the parameters extracted from multi-bias S-parameter measurements do not fulfill simple consistency requirements. This paper presents a new method to extract a dynamic model from the measurements of the S-parameters through a physics-based correction of the extracted conductance parameters.

Electrophysiological Analysis of the Yeast V-Type Proton Pump: Variable Coupling Ratio and Proton Shunt

Isolated vacuoles from the yeast Saccharomyces cerevisiae were examined in the whole-vacuole mode of patch recording, to get a detailed functional description of the vacuolar proton pump, the V-ATPase. Functioning of the V-ATPase was characterized by its current-voltage (I-V) relationship, obtained for various levels of vacuolar and cytosolic pH. I-V curves for the V-ATPase were computed as the difference between I-V curves obtained with the pump switched on (ATP, ADP, and P i present) or off (no ATP). These difference current-voltage relationships usually crossed the voltage axis within the experimental range (from −80 to +80 mV), thus measuring the reversal voltage ( E R) for the V-ATPase, which could be compared with the standing ion gradients and free energy of ATP hydrolysis, to calculate the apparent pump stoichiometry or coupling ratio: the number of protons transported for each ATP molecule hydrolyzed. This ratio was found to depend strongly upon the pH difference (ΔpH) across the vacuolar membrane, being ∼2H +/ATP at high ΔpH (4 pH units) and increasing to >4H +/ATP for small or zero ΔpH. That result is in quantitative agreement with previous determinations on plant vacuoles. Considerations of purely electrical behavior, together with the physical properties of a recent detailed structural model for V-ATPases, led to a linear equivalent circuit—which quantitatively accounts for all observations of variable coupling ratios in fungal and plant V-ATPases by variations of the conductance for bona fide proton pumping ( G P) through the ATPase relative to independent proton shunting ( G S) through the same protein.

Determination of performance characteristics of a single-phase shaded pole induction motor by circuit-field method

A circuit-field combined method with reference to performance characteristics evaluation of a single-phase shaded pole induction motor is described. Features of material–structure construction of the motors are taken into account. The circuit-field equations with electromagnetic parameters and a procedure of solutions for sinusoidal approximation are determined. The circuit-field equations are solved for each value of slip in a double iteration process where non-linear potential equations are solved in the internal loop, and the linear complex circuit equations are solved in the external loop. Exemplary studies of the influence of magnetic shunts and the resistance of shading coils on performance characteristics of the motor are presented. The calculated performance characteristics of a tested motor are compared with measurements while taking into account magnetization characteristics.

Bias-dependent linear scalable millimeter-wave FET model

This paper describes a measurement-based bias-dependent linear equivalent circuit field-effect-transistor/high-electron-mobility-transistor model that is accurate to at least 100 GHz and scalable up to 12 parallel gate fingers and from 100 to 1000 /spl mu/m total gate width. A new and accurate technique for extracting the Z-shell parameters has been developed, and the scaling rules for all the parasitic elements have been determined. The intrinsic equivalent circuit element values are determined at each bias point in V/sub ge/-V/sub ds/ space and interpolated by splines between points.

Potential transients for an electrochemical corrosion reaction under constant current conditions

Due to the electrochemical nature of almost all corrosion reactions, electrochemical methods are commonly used to measure the corrosion rate of a metal in the laboratory or in the field. In particular, steady state methods are the most widely used for corrosion rate measurements. Transient methods, which can be much more efficient, traditionally rely on an equivalent linear circuit representing the surface kinetics, with negligible mass transport effects. This has been reported to predict transients which are not observed experimentally in many practical situations. In this paper, we consider the galvanostatic method, wherein a constant current is applied across a corroding metal surface and the transient potential response is recorded. The resulting boundary value problems incorporating mixed kinetic and diffusion control involve highly nonlinear, coupled boundary conditions. We present numerical and approximate analytical solutions which can be incorporated into corrosion analysis routines in order to calculate corrosion parameters. The analytical expressions open the possibility of measuring corrosion parameters by merely fitting a class of elementary functions to experimental potential transients. This leads to a significant reduction in the number of computations required for the curve fitting, and hence increasing the overall efficiency of the measurement process compared to the conventional steady state methods.

Iteratively reweighted least squares for maximum likelihood identification of synchronous machine parameters from on-line tests

This paper presents a new approach for the statistical identification of synchronous-machine parameters from on-line test data that were recorded on a 202 MVA hydro-generator at Hydro-Quebec's La Grande 3 generating station. Data processing is performed to remove harmonics in noise-corrupted measurements. The time-domain parameter identification is carried out by means of our proposed maximum-likelihood estimation method, also called the iteratively reweighted least-squares algorithm. A comparison of the results with the ordinary weighted least-squares estimation, which is equivalent to the maximum-likelihood estimation only when the noise is white, shows the superiority of the proposed method. This procedure appears more convenient than previous schemes for parameter identification of the synchronous-machine linear equivalent-circuits, especially when the noise statistics are poorly known.

Simulation of Magnetostatic Wave Envelope Soliton Propagation in Yttrium Iron Garnet Films

Although formation and propagation of magnetostatic soliton waves in YIG (yttrium iron garnet) films are attracting great attention, there has been no discussion about simulating soliton formation and propagation in YIG films from the viewpoint of circuit analysis and simulation. In this report, we propose a new algorithm to simulate the magnetostatic soliton wave output. We first describe the linear magnetostatic wave equivalent circuit model we have developed and then discuss the simulation algorithm, which combines the linear equivalent circuit model and the soliton wave solution of the nonlinear Schrödinger equation. The simulated results are in excellent agreement with reported experimental results. We also find that the proposed simulation is very effective to determine various physical parameters in the YIG film for given experimental conditions.

A small-signal linear equivalent circuit of HEMTs fabricated on GaAs-on-Si wafers

A small-signal linear equivalent circuit of HEMTs fabricated on GaAs-on-Si wafers

Modeling and performance analysis of a fiber Bragg grating interrogation system using an acousto-optic tunable filter

The performance of a fiber grating interrogation system using an acousto-optic tunable filter (AOTF) is analyzed. An equivalent linear circuit is presented to describe the system, which tracks the wavelength of a fiber Bragg grating (FBG) sensor in a FBG sensor array. From the model, the tracking resolution of a shot-noise-limited system has been determined for both transmissive and reflective interrogation of FBGs. An optimum ratio between the bandwidths of the FBG and the AOTF has been derived. Experimental results of a tracking system are presented to validate the theoretical predictions. The theory should also be suitable for interrogation systems using other forms of tunable bandpass filters for tracking the FBG wavelength.

A generalized theory of intensity modulated photocurrent spectroscopy (IMPS)

A generalized theoretical model of intensity modulated photocurrent spectroscopy (IMPS) is proposed, and analytical equations for the frequency dependence of the photocurrent and photovoltage responses are derived. The theory treats the influence of the space charge, the surface state and the Helmholtz capacitances on the IMPS response. In the model, charge transfer and recombination at the semiconductorvbelectrolyte interface are described by kinetic equations, whereas surface state charging and the current through the external circuit are treated using linear circuit equations. The calculated IMPS plots exhibit a number of useful diagnostic features. The treatment also shows that it should be possible to measure the space charge capacitance directly from the photovoltage response, even if it is comparable in magnitude with the Helmholtz capacitance. Equivalent circuits representing the processes occurring during IMPS measurements are discussed, and it is shown that single passive elements do not provide a satisfactory description of the kinetic steps responsible for the photocurrent response.

An ultra low cost and miniature 950–2050 MHz GaAs MMIC downconverter‐I: Design approach and simulation

Abstract A miniature ultra low cost 950–2050 MHz GaAs MMIC downconverter has been designed for satellite TV application using a 1‐μm gate‐length, ion‐implanted GaAs MESFET foundry process. To accurately predict circuit performances, both linear and nonlinear equivalent circuit models have been developed to characterize the RF and dc behaviors of device. Modeled simulation results show correspondence with the experimental data. This monolithic downconverter is comprised of an RF LNA, a dual‐gate MESFET mixer, an IF variable gain amplifier, and a varactor tuned oscillator. The primary design specifications are (1) 50‐dB conversion gain, (2) 4‐dB noise figure, (3) more than 40‐dB gain controllable range, and (4) 50‐dBc third‐order intermodulation distortion. The chip size is 1.4 × 1.5 × 0.18 mm3. It is encapsulated in a standard low cost plastic package. Moreover, this downconverter IC is promising for miniaturization and cost‐reduction of a DBS receiver. The detailed measured characteristics will be presented in part‐II of this paper.

Node and mesh analysis by inspection

This paper shows how to write node or mesh analysis linear circuit equations by inspection of the circuit schematic diagram and obtains two different matrix solutions of these equations. The linear circuit can have resistances or impedances, controlled sources, ideal operational amplifiers, or mutually coupled coils. The first matrix solution finds the node-voltage or mesh-current vector in terms of matrix operations with the inspection matrices. Also, this method gives a matrix solution for any arbitrary output vector in terms of the node-voltage or mesh-current solution vector, the independent-source vector, and the inspection matrices. The second matrix solution method finds the solution for a vector consisting of all node voltages or mesh currents, dependent sources, controlling variables, and any output variable(s) using a single matrix equation. Matrix methods of circuit analysis are now appropriate for student use because of the existence of calculators capable of solving large matrices and the availability of inexpensive math programs for personal computers. >

Transient analysis of nonlinear circuits by combining asymptotic waveform evaluation with Volterra series

A new method is proposed for the transient analysis of circuits with large number of linear lumped elements and lossy coupled transmission lines, and with few mildly nonlinear terminations. The method combines the Volterra-series technique with Asymptotic Waveform Evaluation approach and corresponds to recursive analysis of a linear equivalent circuit. >

Chaos and magnetospheric dynamics

Abstract. Our intention in this work is to show, by using two different methods, that magnetospheric dynamics reveal low dimensional chaos. In the first method we extend the chaotic analysis for the AE index time series by including singular value decomposition (SVD) analysis in combination with Theiler's test in order to discriminate dynamical chaos from self-affinity or "crinkliness". The estimated fractality of the AE index time series which is obtained belongs to a strange attractor structure with close returns in the reconstructed phase space. In the second method we extend the linear equivalent magnetospheric electric circuit to a nonlinear one, the arithmetic solution of which reveals low dimensional chaotic dynamics. Both methods strongly support the existence of low dimensional magnetospheric chaos.

A non‐linear and distributed modelling procedure of fets

AbstractThis paper describes a rigorous and systematic procedure to derive a non‐linear distributed FET model that an easily be implemented in CAD routines of simulators based on harmonic balance techniques. The new model is derived from a knowldge of the conventional linear lumped equivalent circuit, from non‐linear current sources extracted with pulsed measurements, and from the physical dimensions of the FET.For fundamental and haromonic requencies, the FET is modelled by N identical cells. Each cell is made up of a non‐linear two‐port section inserted between two linear four‐port sections that simulate the coupling and the distributed effects along the electrodes of the FET in the width direction only. This non‐linear distributed scaling approach to FET modelling has been applied to the analysis of a submicrometre‐gate GaAs FET at Millimetre‐wave frequencies, and the results were compared to the non‐linear lumped element approach. This approach can be applied to other transistors used in non‐linear regions at microwave and millimetre‐wave frequencies.

Modelling the Multiplicity of Conductance Structures in Clusters of Silicon Quantum Dots

ABSTRACTWe have fabricated diode structures containing clusters of nanoscale silicon particles. The modelling of the observed multiple current steps from resonant tunnelling through the quantum states of these particles is presented. Whenever the applied voltage aligns the Fermi surface of the contact to a discrete state, conduction results. Since the clusters are connected in parallel, successive connections of parallel current paths can cause multiple current steps. These current steps can be drastically amplified by avalanche multiplication when the substrate is deeply depleted. The transport in this regime is quite nonlinear, and cannot be represented by a linear equivalent circuit. Apart from gaining a fundamental understanding of the measured I-V characteristics of our diodes, our results serve to promote new applications for quantum switches.

A non‐linear and distributed modelling procedure of fets

AbstractThis paper describes a rigorous and systematic procedure to derive a non‐linear distributed FET model that can easily be implemented in CAD routines of simulators based on harmonic balance techniques. The new model is derived from a knowledge of the conventional linear lumped equivalent circuit, from non‐linear current sources extracted from pulsed measurements, and from the physical dimensions of the FET.For fundamental and harmonic frequencies, the FET is modelled by N identical cells. Each cell is made up of a non‐linear two‐port section inserted between two linear four‐port sections that simulate the coupling and the distributed effects along the electrodes of the FET in the width direction only. This non‐linear distributed scaling approach to FET modelling has been applied to the analysis of a submicrometre‐gate GaAs FET at millimetre‐wave frequencies, and the results were compared with the non‐linear lumped element approach. This approach can be applied to other transistors used in non‐linear regions at microwave and millimetre‐wave frequencies.

Circuit model for a symmetrical condensed TLM node

AbstractAn equivalent circuit for a symmetrical condensed TLM node is presented. The basic circuit has twelve ports and consists of 24 1:1 ideal transformers. Three additional conductances model the conductivity of the medium. The circuit is extended with additional ideal transformers giving six ports for short‐circuit and open‐circuit stubs which model the permittivity and permeability of the inhomogeneous medium. The scattering matrix of the 18‐port network is determined symbolically by solving a set of linear circuit equations. The matrix agrees with previously published results for a symmetrical condensed TLM node, obtained from Maxwell's equations.