Behavioral Fault Modeling and Simulation Using VHDL-AMS to Speed-Up Analog Fault Simulation

One of the main requirements for generating test patterns for analog and mixed-signal circuits is fast fault simulation. Analog fault simulation is much slower than the digital equivalent. This is due to the fact that digital circuit simulators use less complex algorithms compared with transistor-level simulators. Two of the techniques to speed up analog fault simulation are: fault dropping/collapsing, in which faults that have similar circuit responses compared with the fault-free circuit response and/or with another faulty circuit response are considered equivalent; and behavioral/macro modeling, whereby parts of the circuit are modeled at a more abstract level, therefore reducing the complexity and the simulation time. This paper discusses behavioral fault modeling to speed-up fault simulation for analog circuits.     

磁路与电路的对偶性案例：绝缘磁芯变压器

在电气工程专业课程中,电路和磁路既有区别又相互联系。本文以绝缘磁芯变压器为例,在建立其磁路模型的基础上,利用磁路与电路之间的对偶性,采用通用、系统的方法获得了其等效电路模型。与理想变压器相比,绝缘磁芯变压器存在漏磁,且磁路含多个网孔,是学生理解电路对偶性、磁路对偶性以及磁路和电路之间对偶性的典型案例。     

Circuit model for coupling between MMICs in multichip modulesincluding resonance effects

This paper describes a circuit model to be used for the approximate calculation of coupling between monolithic microwave integrated circuits (MMICs) in a multichip module. The model is developed from basic electromagnetic principles and relies on the formation of equivalent electric dipoles to represent the complex currents on the various MMICs within the module. The technique is suitable for use in layout-based circuit simulators and uses no numerical analysis     

A formulation for analog behavioral-level sensitivity and steady-state analysis

The synthesis and verification of larger analog systems in the context of mixed signal ASICs requires formulation of simulation and analysis methods at the analog behavioral level. In this paper we present a formulation for sensitivity and steady state analysis of analog systems at the behavioral level. This formulation is useful for analysis and design space exploration of higher-level analog architectures synthesized from behavioral specifications. Conventional methods are formulated within the context of circuit level simulators such as SPICE, forcing the designer to model systems in terms of primitive circuit-level equivalent circuits thereby taking away advantages of higher level system modeling and simulation.     

Magnetic-shield-type fault current limiter equivalent circuit

In order to investigate how a superconducting fault current limiter (SFCL) can enhance the performance of a power system, an accurate circuit model of the device needs to be introduced in power system simulators. In this paper, we present a finite-element numerical model to calculate the time evolution of the voltage across a magnetic-shield-type SFCL, when it is connected to an external circuit. The calculation of the voltage is carried out by using the energy conservation law, and requires the calculation, at any instant, of the current density distribution inside the superconducting tube and magnetization distribution inside the ferromagnetic core of the device. These distributions are determined by means of two coupled equivalent electric and magnetic circuits, whose topology and components are obtained through the spatial integration of quasi-static form of Maxwell equations. Comparisons between numerical and experimental results are shown.     

Small-signal modeling of nonideal magamp PWM switch

Circuit-based small-signal models of the magnetic amplifier (magamp), which include the effects of the nonideal squareness of the magamp's core B-H curve, are derived for both the voltage-reset and current-reset control techniques. Since, in this modeling approach, the small-signal behaviour of the magamp is described by equivalent circuits, circuit simulators can easily be used to facilitate the control-loop design optimization of the magamp     

Common- and differential-mode HF current components in AC motors supplied by voltage source inverters

In this paper, an inverter-fed ac motor drive is analyzed in order to investigate the conducted electromagnetic interferences at both the input and output sides of the inverter. HF lumped equivalent circuits for the inverter and the motor stator windings are proposed. The overall circuit model allows time- and frequency-domain analysis to be performed with standard circuit simulators. The proposed model can also predict common- and differential-mode HF current components. The equivalent circuit is verified by experimental tests carried out on a prototype of ac motor drive.     

An experimentally verified hybrid Cassie-Mayr electric arc modelfor power electronics simulations

This paper presents an electric arc model that can approximately represent both the static and dynamic characteristics of an arc load controlled by a power electronic circuit. The proposed model was developed from the combination and modifications of the classical Cassie and Mayr equations. The model equations have been expressed in a form suitable for incorporation into circuit simulators employing the nodal analysis method of equation solving. The model has been test-implemented in the Saber circuit simulator. Simulated and experimental results appear to be in good agreement     

An improved GaAs device model for the simulation of analog integrated circuit

This paper describes an improved device model of GaAs MESFETs and heterojunction FETs for the design and analysis of analog integrated circuits. The proposed device model provides a new expression for the current and the capacitance of the device,which gives excellent agreements with experimental data for all regions of device operation. For the expression of the low frequency anomalies of GaAs devices, an improved technique with an equivalent circuit are presented to model the frequency dispersion of the transconductance and the drain conductance of the device, which give a good agreement with the experimental data of both the frequency dispersion and the lag effect of the device. The new device model proposed here clearly provides a superior prediction of the performance of GaAs analog integrated circuit.     

Characteristic Analysis of Interior Permanent-Magnet Synchronous Motor in Electrohydraulic Power Steering Systems

This paper presents design and analysis results of a 2.6-kW interior permanent-magnet synchronous motor developed for an electrohydraulic power steering system. The motor was designed by using the proposed equivalent magnetic circuit model in consideration with a core loss. To analyze motor characteristics by using the equivalent magnetic circuit model, inductance and iron-loss resistance, which are affected critically by magnetic saturation, are obtained by using finite-element analysis. Finally, motor characteristics such as armature current, torque, and efficiency are calculated by the equivalent magnetic circuit model and verified by experimental results.     

Parametric macromodels of differential drivers and receivers

This paper addresses the modeling of differential drivers and receivers for the analog simulation of high-speed interconnection systems. The proposed models are based on mathematical expressions, whose parameters can be estimated from the transient responses of the modeled devices. The advantages of this macromodeling approach are: improved accuracy with respect to models based on simplified equivalent circuits of devices; improved numerical efficiency with respect to detailed transistor-level models of devices; hiding of the internal structure of devices; straightforward circuit interpretation; or implementations in analog mixed-signal simulators. The proposed methodology is demonstrated on example devices and is applied to the prediction of transient waveforms and eye diagrams of a typical low-voltage differential signaling (LVDS) data link.     

Enhanced CAD model for gate leakage current in heterostructurefield effect transistors

A simple and accurate circuit model for Heterostructure Field Effect Transistors (HFETs) is proposed to simulate both the gate and the drain current characteristics accounting for hot-electron effects on gate current and the effect of the gate current on the channel current. An analytical equation that describes the effective electron temperature is developed in a simple form. This equation is suitable for implementation in circuit simulators. The model describes both the drain and gate currents at high gate bias voltages. It has been implemented in our circuit simulator AIM-Spice, and good agreement between simulated and measured results is achieved for enhancement-mode HFETs fabricated in different laboratories. The proposed equivalent circuit and model equations are applicable to other compound semiconductor FETs, i.e., GaAs MESFETs     

Equivalent circuit model of on-wafer CMOS interconnects for RFICs

This paper investigates the properties of the on-wafer interconnects built in a 0.18-/spl mu/m CMOS technology for RF applications. A scalable equivalent circuit model is developed. The model parameters are extracted directly from the on-wafer measurements and formulated into empirical expressions. The expressions are in functions of the length and the width of the interconnects. The proposed model can be easily implemented into commercial RF circuit simulators. It provides a novel solution to include the frequency-variant characteristics into a circuit simulation. The silicon-verified accuracy is proved to be up to 25 GHz with an average error less than 2%. Additionally, equivalent circuit model for longer wires can be obtained by cascading smaller subsections together. The scalability of the propose model is demonstrated.     

Transient Analysis of a Stripline Having a Corner in Three-Dimensional Space

The transient analysis of electromagnetic fields has shown its utility not only in clarifying the variation of the fields in time but also in gaining information on mechanisms by which the distributions of an electromagnetic field at the stationary state are bronght about. We have recently proposed a new numerical method for the transient analysis in three-dimensioual space by formulating the equivalent circuit based on Maxwell's equation by Bergeron's method. The resultant nodal equatiou is uniquely formulated in the equivalent circuit for both the electric field and the magnetic field. In this paper, we deal with the stripline which should be analyzed essentially in three-dimensionaf space because of its structure, The time variation of the electric and magnetic field of the stripline having a comer is analyzed and the remarkable changing of distribution of the field is presented as a parameter of time and of conditions imposed by the corner stucture.     

A generalized dynamic circuit model of magnetic cores for low- andhigh-frequency applications. I. Theoretical calculation of theequivalent core loss resistance

This paper describes the theoretical calculation of the equivalent core loss resistance for a dynamic magnetic core loss model. The equivalent core loss resistance incorporates the effects of both the classical eddy current and anomalous losses. Derivation of a generalized nonlinear core loss resistance expression is presented. This new equivalent core loss resistance can be incorporated into a generalized dynamic magnetic core circuit model suitable for low and high frequency applications     

Equivalent circuit for multiple vias in parallel plate environment

An equivalent one-dimensional circuit has been developed to model the loading effects of vias (through or buried) in a parallel plate environment. Owing to the one-dimensional nature of the model, the simulation time is dramatically reduced, compared to either two-dimensional inductance-capacitance ladder network or full-wave numerical electromagnetic simulations. This model can be easily included in available commercial circuit simulators and accounts for multiple via interactions as well as for substrate edge reflections     

Modeling Magnetic Radiations of Electronic Circuits Using Near-Field Scanning Method

In this paper, a simple method to obtain the equivalent radiation emitting sources of an electronic circuit using the near-field scanning method is presented. The model is based on a set of elemental dipoles that substitutes the electronic circuit and radiates the same magnetic field. Two different approaches are presented: a set of electric dipoles and a set of magnetic dipoles. In order to build the model, both the magnitude and phase of the magnetic field are required. These measurements are carried out using the "near-field scanning method," and two procedures are presented: using the vector network analyzer and the spectrum analyzer. Finally, the model is applied to two different cases: to obtain the radiated near-field of a component (microcontroller) and to obtain the field of a complete electronic board.     

Modeling and measurement of substrate coupling in Si-bipolar IC'sup to 40 GHz

Parasitic substrate coupling can severely degrade the performance of high-speed ICs and must be considered carefully in circuit design. Therefore, this paper proposes several equivalent circuits that are well suited for modeling substrate coupling up to very high frequencies with standard circuit simulators such as SPICE. Their element values can be calculated for arbitrary layout configurations from numerical simulations (using our SUbstrate SImulator SUSI), which are based on experimentally determined, specific technological/electrical data. The validity of both the simulator and the equivalent circuits has been verified by on-wafer measurements up to 40 GHz, the highest frequency reported so far for modeling of substrate coupling. For this, special test structures were designed and fabricated in an advanced Si-bipolar technology. This work is focused on substrate modeling in very-high-speed rather than in complex ICs     

ISAAC: a symbolic simulator for analog integrated circuits

The symbolic simulator ISAAC (interactive symbolic analysis of analog circuits) is presented. The program derives all AC characteristics for any analog integrated circuit (time-continuous and switched-capacitor, CMOS, JFET, and bipolar) as symbolic expressions in the circuit parameters. This yields analytic formulas for transfer functions, CMRR (common-mode rejection ratio), PSRR (power-supply rejection ratio), impedances, noise, etc. Two novel features are included in the program. First, the expressions can be simplified with a heuristic criterion based on the magnitudes of the elements. This yields interpretable formulas showing only the dominant terms. Second, the explicit representation of mismatch terms allows the accurate calculation of second-order effects, such as the PSRR. ISAAC provides analog designers with more insight into the circuit behavior than do numerical simulators and is a useful tool for instruction or designer assistance. Moreover, it generates complete analytic AC circuit models, which are used for automatic sizing in a nonfixed topology analog module generator. The program's capabilities are illustrated with several examples. The efficiency is established by a dedicated sparse-matrix algorithm     

Circular-pad via model based on cavity field analysis

An equivalent circuit model of a circular-pad grounding via is proposed based on cavity modal analysis. The modes of the via are derived analytically. Each mode is represented by an equivalent circuit taking into account ohmic losses, as well as losses due to spatial and surface wave radiation. It is shown that the degradation of grounding via characteristics at high frequencies is caused by the multimode effects and radiation. The accuracy of the proposed semi-analytical via model is comparable with that of full-wave analysis up to 75 GHz. It is fast and is easily incorporated in high-frequency circuit simulators.