Showing papers on "Equivalent circuit published in 1985"

A Nonlinear GaAs FET Model for Use in the Design of Output Circuits for Power Amplifiers

Abstract: A nonlinear equivalent circuit model for the GaAs FET has been developed based upon the small-signal device model and separate current measurements, including drain-gate avalanche current data. The harmonic-balance technique is used to develop the FET RF load-pull characteristics in an amplifier configuration under large-signal operation. Computed and experimental load-pull results show good agreement.

Fractal model for the ac response of a rough interface

Abstract: A fractal model is proposed for a rough interface between two materials of very different conductivities, e.g., an electrode and an electrolyte. The equivalent circuit of the model, which takes into consideration the resistance in the two substances and the capacitance of the interface, has the property of the so-called constant-phase-angle element, i.e., a passive circuit element whose complex impedance has a power-law singularity at low frequencies. The exponent of the frequency dependence is related to the fractal dimension. The model also provides insight into the conducting properties of the percolating cluster and the source of the 1/f noise in electronic components.

AC Impedance Analysis of Polycrystalline Insertion Electrodes: Application to Li1 − xCoO2

Abstract: It is argued that a porous insertion electrode can be modeled, for purposes of ac impedance analysis, by a modified Randles equivalent circuit containing a generalized constant-phase-angle impedance in series with the double-layer capacitance. The impedance spectrum of the disintercalation system Li/sub 1//sup -/..integral..CoO/sub 2/ showed two time-dependent semicircles, indicating the need for a further modification of the equivalent circuit by a physical process tha could be represented by a resistor/capacitor combination. An adsorption process and a Li/sup +/-ion-electrolyte surface layer are each shown to refine to identically low R factors and to be represented by equivalent circuits that transform on into the other, each having circuit values with reasonable values for the physical processes represented. Time-dependent experiments could eliminate the adsorption models, and electron microscopy gave direct evidence for the surface-laye model; further indirect evidence came from constant-voltage experiments and the preparation of electrodes with greater electrode/electrolyte interface area. Although propylene carbonate appears to be kinetically stabl in contact with Li/sub 1//sup -/..integral..CoO/sub 2/ at potentials of up to 4.5V vs. lithium, mixtures of propylene carbonate with oxide particles having /chi/ = 0.34 produce thick polymer films.

Computer Calculation of Large-Signal GaAs FET Amplifier Characteristics

Abstract: A simple and efficient method of GaAs FET amplifier analysis is presented. The FET is represented by its circuit-type nonlinear dynamic model taking into account the device's main nonlinear effects including gate-drain voltage breakdown. An identification procedure for extraction of the model parameters is described in detail and examples are given. The calculation of the amplifier response to a single-input harmonic signal is performed using the piecewise harmonic balance technique. As this technique is rather time-consuming in its original form, the optimization routine used to solve the network equations was replaced by the Newton-Raphson algorithm. Characteristics calculated with the use of the proposed method are compared with experimental data taken for a microwave amplifier using a 2SK273 GaAs FET unit. Good agreement at 9.5 GHz over wide ranges of bias voltage and input power levels are observed.

Two-dimensional device simulation program: 2DP

Abstract: Mathematical details of a two-dimensional semiconductor device simulation program are presented, Applicability of the carrier transport model to shallow junction bipolar transistors is discussed. Use of this program to optimize device structures in new bipolar technology is illustrated by presenting calculated device characteristics for variations in a few selected process conditions, Software links that automatically transfer data from a two-dimensional process simulation program and to a quasi-three-dimensional device equivalent circuit model generation program are also discussed.

Resonant length of longitudinal slots and validity of circuit representation: Theory and experiment

Abstract: Pertinent theory for the design of longitudinal slot arrays is reviewed and its dependence on the dominant mode scattering off a single slot is pinpointed. The critical need to know resonant length versus slot offset is emphasized and the desirability of determining this information theoretically rather than experimentally is argued. Then method of moments solutions are used to calculate resonant length versus slot offset for given waveguide dimensions and frequency. These theoretical results are compared to new, carefully obtained experimental data. Agreement is found to be so good, it is concluded that one can dispense with the costly gathering of experimental input data when designing longitudinal slot arrays fed by standard rectangular waveguide. A critical look is taken at the validity of representing the longitudinal slot as a shunt element on an equivalent transmission line. This assumption is found to be more and more questionable as the b dimension is reduced. For quarter-height guide, an alternate design procedure is suggested as being more accurate.

Frequency-Dependent Characteristics of Microstrip Discontinuities in Millimeter-Wave Integrated Circuits

Abstract: A theoretical approach for the representation of microstrip discontinuities by equivalent circuits with frequency-dependent parameters is presented. The model accounts accurately for the substrate presence and associated surface-wave effects, strip finite thickness, and radiation losses. The method can also be applied for the solution of microstrip components in the millimeter frequency range.

Equivalent-circuit formulas for metal grid reflectors at a dielectric boundary.

Abstract: This paper points out a number of errors that have appeared in the literature concerning transmission-line models for metal grid reflectors (strip gratings and meshes) especially in regard to the design of laser mirrors and filter elements for use at submillimeter wavelengths. General formulas are given for the transmittance of lossy grids and for the equivalent circuit impedances to be used in these formulas for strip gratings and meshes at a plane boundary between two lossless dielectrics. The results apply for normal incidence and for wavelengths in both dielectrics greater than the grid period. Limitations of the transmission-line models for meshes at dielectric boundaries are discussed.

A Systematic and Unified Approach to Modeling Switches in Switch-Mode Power Supplies

Abstract: This paper describes a new, systematic, and unified approach to model the low-frequency behavior of power switches in Switch-Mode Power Supplies (SMPS). This approach starts with a simplification of the switching converter circuit to a Minimum Separable Switching Configuration (MISSCO) containing all power switches but a minimum number of other components, before analysis on the MISSCO is carried out. Then by making use of an impulse-response method and averaging technique, a set of equations describing the low-frequency behavior of the MISSCO are derived. The resultant equations can be used to generate a low-frequency equivalent circuit of the MISSCO, which can then be combined with the rest of the SMPS circuit to form a complete equivalent circuit.

ESD on CHMOS Devices - Equivalent Circuits, Physical Models and Failure Mechanisms

Abstract: Using new techniques it is possible to construct an EOS/ESD equivalent circuit of a product. Location of energy dissipation during an EOS/ESD event is determined by a pulsed near infrared technique. Rules for predicting location of ESD dissipation are defined. N+-P-N+ structures and n-channel transistors suffer from a current lock-on effect, which is apparently caused by a runaway oxide trapping mechanism. Different failure mechanisms are observed at narrow and wide pulse widths. Hot electron induced damage occurs under mechanical handling conditions. On CMOS outputs the n-channel device absorbs most of the ESD, and is very fragile.

Signal delay device

Abstract: A signal delay device comprises a CMOS gate circuit (12, 14) having an input terminal (13) to which a binary input signal to be delayed is applied, an output terminal (15) from which a delayed signal is derived and power voltage supply terminals to which operation power voltages are applied. The delay time of the CMOS gate circuit depends upon voltage applied to it and, utilizing this phenomenon, voltage control means (16,18) is provided in a power supplying path for the CMOS gate circuit for controlling voltage applied to the CMOS gate circuit. The signal delay device using the CMOS gate circuit is applied to various circuits including an analog signal delay circuit, a jitter absorption circuit and a fixed head type magnetic tape reproducing device.

SAMSON2: An Event Driven VLSI Circuit Simulator

Abstract: This paper describes the circuit simulation algorithms of the SAMSON2 mixed circuit/logic simulator. SAMSON2 employs event driven simulation techniques to exploit the inherent temporal sparseness in VLSI circuits. At the circuit level, SAMSON2 can be more than an order of magnitude faster than a "standard" circuit simulator such as SPICE2 while providing comparable waveform accuracy. This performance is achieved by partitioning a circuit into subcircuits which are allowed to have separate integration step sizes reflecting their activity level. The accuracy of the solution is maintained by controlling the errors due to decoupling among the subnetworks as well as the local truncation within each subnetwork. Simulation examples of typical MOS integrated circuits (IC's) are presented. f

Minimizing dc drift in LiNbO3 waveguide devices

Abstract: Improved stability against electrical dc bias drift has been demonstrated in LiNbO3 electro‐optic modulators by replacing the commonly used SiO2 buffer layer with indium tin oxide (ITO), a transparent conductor. The long term drift of the modulators having an ITO buffer layer with a sheet resistivity of ∼20 Ω/⧠ is less than 0.3% in 8 h. The mechanism of the dc drift phenomenon is discussed using an electrical equivalent circuit model of the modulator.

Invited paper Characteristics of travelling waves along the non-linear transmission lines for monolithic integrated circuits: a review

Abstract: A general analysis of non-linear wave propagation along transmission lines with voltage-dependent capacitance is presented. In particular, slow-wave structures like MIS and Schottky-barrier strip lines are examined. A spatial periodicity is included explicitly. The theoretical treatment is based on suitable equivalent circuits leading to characteristic wave equations. With regard to practical devices, the solutions show a variety of different phenomena as determined by the parameters of the non-linearity, dispersion and dissipation and the boundary conditions. Experimental results performed on a slow-wave model line are included.

Generator for a custom statistical bipolar transistor model

Abstract: An automated model generator (MG) has been developed for a rectangular bipolar device with arbitrary and nonsymmetrical separations of rectangular regions around the emitter perimeter. The MG provides a transistor equivalent circuit whose parameters are determined using a distributed network representing a three-dimensional transistor configuration. The network accounts for nonlinear device dependencies associated with horizontal layout and process technologies. The elements of the distributed network are simple units whose parameters ar derived from measurements or two-dimensional process and device simulations. The MG is versatile and offers several photolithography and processing technology options, with recessed oxide or oxide-nitride defined standard or polysilicon-type base. The resulting lumped-equivalent circuit is used, along with related models of other transistors or device types, for statistical analysis computations of various circuit configurations at different operating temperatures.

Radial-line/coaxial-line junctions: analysis and equivalent circuits

Abstract: An exact analysis of a radial-line/coaxial-line junction is presented. An equivalent is deduced for the junction for the case where only the dominant modes can propagate in the radial and coaxial lines. The expressions for the equivalent circuit are in terms of the unknown coaxial aperture electric field. It is shown that only one component of the equivalent circuit is affected to any extent by approximation of the aperture field. Expressions for the equivalent circuit are then obtained using the TEM approximation. Finally, two modified junctions are considered.

Computer-Aided Noise Analysis of Linear Multiport Networks of Arbitrary Topology

Abstract: The paper discusses a new algorithm for the noise analysis of a linear multiport network. The circuit may include any kind of passive components introducing thermal noise only, and any number of two-port devices described by the usual four noise parameters. On output, the algorithm produces the correlation matrix of the Norton equivalent noise current sources at the network ports. The approach is suitable for implementation into any general-purpose microwave circuit design program.

Theoretical of and Experimental Investigation Finline Discontinuities

Abstract: The dominant and the first-five higher order modes in a unilateral finline are precisely described from a thorough spectral-domain approach Then, using the modal analysis, coupling coefficients between eigenmodes at a discontinuity that have to be introduced into the scattering matrix formulation are directly computed in the spectral-domain, and, consequently, the equivalent circuit parameters of the discontinuity are determined Finafly, finline discontinuities often used for impedance transformation are investigated and a good agreement between theoretical and experimental results is reported

Development and Interrupting Tests on 250KV 8KA HVDC Circuit Breaker

Abstract: This paper describes the circuit and component selections, development and equivalent circuit test results on an HVDC circuit breaker for an HVDC transmission line A puffer type SF 6 gas interrupter for AC circuit breakers is utilized for interrupting DC current with injection of high-frequency inverse current from a commutating capacitor precharged to HVDC line voltage Also, the effectiveness of application of the HVDC breaker to an HVDC system with two parallel transmission lines is demonstrated through the EMTP simulation

Generalised transmission line model for microstrip patches

Abstract: A transmission line model for microstrip configurations, for which separation of variables is possible, is presented. For this, the patch is modelled as a transmission line joining the radiating apertures. Each section of the transmission line is replaced by a π-network. The effect of apertures in the direction perpendicular to the direction of propagation is included through the complex eigenvalues. The effect of mutual coupling between the radiating edges can be described using variational technique and finally incorporated in the equivalent circuit of the structure. Application of the transmission line method appears to be large. Some patch shapes have been analysed and others indicated.

Circuit effect in LiNbO(3) channel-waveguide modulators.

Abstract: An RC circuit is used to model transient effects that occur when dc or quasi-dc voltages are applied to channel-waveguide modulators. These effects are believed to be due to the anisotropic redistribution over time of charge stored in the LiNbO3. The anisotropy arises from the anisotropic material properties and the inhomogeneity induced when channel waveguides are formed. The transient effects measured are not caused by photorefractivity.

Magic's Circuit Extractor

Abstract: We have implemented a fast hierarchical circuit extractor for the Magic VLSI layout system. The keys to its speed are a new algorithm based on corner-stitching, and its ability to extract cells incrementally. Because the extractor is incremental, typically only a few cells must be re-extracted when the layout changes. The extractor computes circuit connectivity and transistor dimensions, both internodal and substrate parasitic capacitance, and parasitic resistances. It is parameterized to work across a wide range of MOS technologies.

Analysis of Multilayer Interconnection Lines for a High-Speed Digital Integrated Circuit

Abstract: A general method for the analysis of multilayer interconnection lines is presented. This method is capable of predicting frequency dispersion of the transmission-line parameters and is useful for accurately investigating the coupling phenomena among adjacent lines and the input and output impedance relations.

A Very Wide-Band Microwave MESFET Mixer Using the Distributed Mixing Principle

Abstract: A new theory of distributed (traveling-wave) mixing is presented. A closed-form expression for the conversion gain is derived. Subsequently, the expression is reduced to a very simple form when the mixer approaches the ideal lossless case. A simplified nonlinear model of a GaAs MESFET is also described. Design criteria and considerations are presented. The relative contributions made by circuit parasitic to the conversion gain-bandwidth product are also examined. Experimental verification on a two-section design is described. It exhibits around 4 dB of conversion loss over the signal frequency band from 2 GHz to the cutoff at 10 GHz for an IF of 1.5 GHz. Experimental results obtained corroborate the theoretical predictions. Better performance is expected if more sections are employed.

Effect of Electrode Contact Resistance On Electric Field Measurements

Abstract: A simple equivalent circuit model and field measurements show that dipolar electric field measurements can be changed by up to 50% due to the effects of electrode contact resistance (RC). The equivalent circuit model shows that a high RC enhances the effective wire-to-ground capacitive coupling, leading to a complex dependence of received voltage on frequency, electrode contact resistance, wire length, and wire capacitance. The model shows that measured electric field voltages will fall between a perfectly grounded asymptote (RC  0) and an ungrounded asymptote (RC  ). Field tests were made of this model using the controlled source audio-frequency magnetotelluric (CSAMT) technique. By varying the effective RC and the signal frequency, the behavior predicted by the model was confirmed. The tests indicate that electrode contact resistance or ECR effects cannot be ignored in CSAMT data, and that they may influence complex resistivity measurements in certain conditions. A simple, workable solution to the ECR problem was devised by inserting a high-impedance amplifier in series with the electrodes and by shielding the lead wires, grounding the shield to a common-mode reference pot. Measurements using this configuration show that ECR effects virtually can be eliminated even at high RC values.

A charge-based large-signal model for thin-film SOI MOSFET's

Abstract: A charge-based large-signal model for thin-film SOI (Si-on-SiO 2 ) MOSFET's, intended for computer simulation of transient characteristics of SOI and 3-D circuits, is developed emphasizing the structural uniqueness of the devices. Closed-form expressions for the quasi-static terminal charges, simpler than those for the bulk MOSFET because of the thin-film structure, are derived in terms of terminal voltages and device parameters, and are used to define the terminal currents. Equivalent circuits, developed from the charge-based model, show that the device can be accurately represented using only real reciprocal capacitances by explicitly accounting for the transient channel transport current I TT . The analytic expression for I TT , obtainable for the thin-film structure, enables the evaluation of the finite-carrier transit delay in the channel and of the corresponding charge nonconservation in the conventional reciprocal-capacitance MOSFET model that does not account for the delay.

Numerical analysis and design for high-performance helix traveling-wave tubes

Abstract: A new design method has been established for helix traveling-wave tubes having higher output powers (over 100 W) and wider bandwidths (2 to over 4 GHz) and capable of stable operation at frequencies in 10 to over 20 GHz bands. It is based on an analytical technique to consider the influences of the tape width, dielectric and shield barrel in the helix slow-wave circuit simultaneously, and also on an analytical technique to solve problems in regard to backward-wave oscillations at higher output powers, matching input and output sections for wider bandwidths, and undesired coaxial modes caused at operating frequencies above 20 GHz. This method realizes practical design of overall high-performance helix traveling-wave tubes with output powers of 250 W in the 14-GHz band and 20 W in the 30-GHz band and a bandwidth of 2 GHz in the 12-GHz band.

The reluctance machine as a self-excited reluctance generator

Abstract: The test described in this paper show that the reluctance machine may be operated as an independent or isolated generator at a predetermined voltage and frequency, with sinusoidal wave form, by moans of capacitive excitation. Further, proper choice and arrangement of the capacitors will result in a practically flat external load-voltage characteristics. The performance analysis based on a developed equivalent circuit is given with experimental verification.