A simulation program emphasized on DC analysis of VLSI circuits: SAMOC

Modified nodal analysis (MNA) can be considered as the most adopted method in circuit simulation programs. Once node equations were written and complemented with those from the current controlled branches, a nonlinear system of algebraic and/or differential equations is obtained. In general, by using linear multistep integration methods, differential equations are recast as nonlinear algebraic ones, which are solved through the Newton method at each integration time step. While computer precision is not an issue in most situations, some specific but frequent cases yield ill-conditioned or singular matrices even in originally well posed circuits. This drawback can occur in different situations namely in presence of strongly nonlinear elements and/or when very small integration time steps are used. In the second case, very large conductances in the companion model of capacitors can introduce roundoff errors. In this paper, a transformation of the MNA that overcomes these problems is proposed. It is based on a suitable recombination of equations and electrical variables of the conventional MNA and it can be easily implemented in a circuit simulator.

This paper presents a state-of-the-art review of the recent advances in computer methods for analysis and design of switched circuits in both time and frequency domains. It also presents new research results on time-domain analysis and sensitivity of switched nonlinear circuits, time- and frequency-domain statistical analysis of switched linear and nonlinear circuits, and efficient modeling and analysis of clock feedthrough and charge injection in switched linear circuits. In time-domain analysis, the modeling of switches and its effect on the simulation of switched circuits are investigated. Formulation methods for these circuits are examined. Inconsistent initial conditions arising from ideal switching are investigated and numerical methods that derive the consistent initial conditions are examined. Sampled-data simulation (SDSIM) of switched linear circuits including clocked sigma-delta modulators is investigated. SDSIM is extended to switched nonlinear circuits. Time-domain sensitivity of switched linear and nonlinear circuits is analyzed using SDSIM. Efficient time-domain statistical analysis of switched linear and nonlinear circuits is introduced, and their effectiveness is assessed using Monte Carlo simulation. Methods that compute the effect of the clock jitter of periodically switched linear (PSL) circuits are examined. Time-domain noise analysis of PSL circuits is investigated. In frequency-domain analysis, exact frequency analysis of multiphase PSL circuits is reviewed. Sensitivity analysis of these circuits is examined in detail. Adjoint network theory and its usefulness in noise and sensitivity analysis of switched linear circuits are studied. Group delay of PSL circuits is investigated briefly. Efficient modeling and analysis of clock feed-though and charge injection of PSL circuits are introduced. Distortion and sensitivity of periodically switched nonlinear circuits with mild nonlinearities are investigated. Finally, frequency-domain noise analysis of PSL circuits is examined.

This book is concerned with circuit simulation using National Instruments Multisim. It focuses on the use and comprehension of the working techniques for electrical and electronic circuit simulation. The first chapters are devoted to basic circuit analysis. It starts by describing in detail how to perform a DC analysis using only resistors and independent and controlled sources. Then, it introduces capacitors and inductors to make a transient analysis. In the case of transient analysis, it is possible to have an initial condition either in the capacitor voltage or in the inductor current, or both. Fourier analysis is discussed in the context of transient analysis. Next, we make a treatment of AC analysis to simulate the frequency response of a circuit. Then, we introduce diodes, transistors, and circuits composed by them and perform DC, transient, and AC analyses. The book ends with simulation of digital circuits. A practical approach is followed through the chapters, using step-by-step examples to introduce new Multisim circuit elements, tools, analyses, and virtual instruments for measurement. The examples are clearly commented and illustrated. The different tools available on Multisim are used when appropriate so readers learn which analyses are available to them. This is part of the learning outcomes that should result after each set of end-of-chapter exercises is worked out. Table of Contents: Introduction to Circuit Simulation / Resistive Circuits / Time Domain Analysis -- Transient Analysis / Frequency Domain Analysis -- AC Analysis / Semiconductor Devices / Digital Circuits

Circuit simulation programs with much higher accuracy than those presently available are required to achieve analog circuits with higher accuracy. For the simulation method which is a factor in determining the accuracy of circuit simulation, a charge‐oriented simulation method has been proposed and utilized effectively. On the other hand, in terms of a device model which is another factor, there has been no current and capacitance model consistent with the forementioned simulation method and available for submicron devices. This paper proposes a submicron CMOS device model which is used in the charge oriented circuit simulation to achieve higher‐accuracy circuit analysis. The features of this model are: (1) continuity of drain conductance at the pinch‐off voltage ensures accurate expression of the drain conductance which is especially important in designing analog circuits; (2) minority carriers in the pinch‐off region are considered to express accurately the current and capacitance characteristics in the saturation region. By comparing the drain current vs. drain voltage characteristics for 0.6 μm and 1.0 μm devices and the capacitance characteristics for a 0.8 μm device reported elsewhere it is shown that the calculated values are in good agreement with the measured values. Thus, our model is confirmed to be applicable to the high‐accuracy design of submicron CMOS circuits.

In this paper, we give an overview of the state-of-the-art in Circuit Analysis, Timing Verification, and Optimization. Emphasis is given to circuit analysis, timing verification and optimization since simulation is covered by C. Terman in this book. Also, the optimization of large circuits is receiving new attention due to the need for timing performance improvement in silicon compilation.

This document is intended to contain a detailed description of the mathematical formulation of Xyce, a massively parallel SPICE-style circuit simulator developed at Sandia National Laboratories. The target audience of this document are people in the role of 'service provider'. An example of such a person would be a linear solver expert who is spending a small fraction of his time developing solver algorithms for Xyce. Such a person probably is not an expert in circuit simulation, and would benefit from an description of the equations solved by Xyce. In this document, modified nodal analysis (MNA) is described in detail, with a number of examples. Issues that are unique to circuit simulation, such as voltage limiting, are also described in detail.

This paper investigates the index of differential‐algebraic equations (DAEs) that arise in modeling of electric circuits with gyrators. A gyrator is a two‐port network element whose constitutive equations are defined by a skew‐symmetric matrix. While the index analysis of DAEs in circuit simulation has been extensively studied, the existing characterizations are not applicable to circuits that include gyrators. For linear time‐invariant circuits with gyrators, we analyze the index of DAEs using a matroid‐theoretic approach. We show that the problem of determining whether DAEs arising from the hybrid analysis have index at most one or not is reduced to a linear matroid parity problem. We also provide a structural characterization for DAEs arising from the modified nodal analysis (MNA), and extend it to nonlinear circuits, generalizing a structural characterization that is well known in the index analysis of the MNA models.

A charge oriented mixed multirate method for a special class of index-1 network equations in chip design

A computer program is described that performs a Volterra-series analysis of a weakly nonlinear microwave circuit having an arbitrary topology. The program uses the method of nonlinear currents and a nodal formulation. In this approach, each nonlinear circuit element is described as a linear element in parallel with a set of current sources; each current source represents a single order (greater than one) of the mixing products, and its current is a nonlinear function of the node-voltage components at lower-order mixing frequencies. The weakly nonlinear circuit is reduced to a linear circuit, which contains the linear elements and the linear parts of the nonlinear elements, and a set of excitation sources. The program is intended primarily for use in the design of microwave circuits; its catalog of circuit elements includes the distributed elements necessary for such work. Because the program formulates and solves the circuit equations numerically, the user need not simplify either the circuit or the model of the solid-state device, or make any of the other common simplifying assumptions. >

Memristor is a two-terminal non-linear passive electrical device. After its recently successful fabrication, a variety of applications based on memristor have been explored, such as non-volatile memory, reconfigurable computing and neural network. However, one major challenge when designing hybrid CMOS memristor integrated circuit is the lack of SPICE-like simulator for design validation. Current approach is to describe memristor device with equivalent circuit, which is however extremely time-consuming for large scale design simulation due to additional modeling components. In this paper, a memristor SPICE simulator is introduced based on the recent new modified nodal analysis (MNA) framework, which can effectively support the non-conventional state variable such as doping ratio of memristor. As such, the memristor device can be stamped into state matrix similarly as one BSIM MOSFET. Compared with equivalent circuit simulation approach, our new MNA based approach exhibits 40x less simulation time for a 32×32 memristor crossbar circuit. A hybrid CMOS memristor circuit for classic conditioning training has also been studied by the developed SPICE simulator.

This paper presents a hybrid approach to the frequency and time domain simulation of complex cable systems with arbitrary linear or linearized circuits at terminations. Depending on the type of cables to be investigated, either FDTD/MNA or MTL/MNA approach can be recommended. In FDTD/MNA scheme 1D-FDTD method is applied to solve the transient response of a cable system, which is then used together with circuits of termination devices to simulate the complete network by modified nodal analysis (MNA). In the second scheme, MTL theory is used to extract equivalent circuit models of cables. All extracted equivalent circuits are then merged with termination devices and solved using specialized MNA-based circuit solver. Both methods are speed-oriented, provide accurate results and can be used for fast simulation of large-scale cable systems. Validation of the proposed methods is performed by comparison with measurements of high voltage shielded cable test setup. Two application examples demonstrate the potential of the proposed approaches for simulation of large-scale cable systems - automotive harness and office wiring network.

This paper presents novel free open-source software JuliaCAP for symbolic analysis of linear time-invariant electric circuits in the complex domain of the Unilateral Laplace Transform or Phasor Transform. Modified Nodal Analysis (MNA) has been chosen for formulation of circuit equations in JuliaCAP. JuliaCAP has been developed by Kristina Rajković, Glorija Došlo, Nikola Radojević, Tamara Petković and Ivana Stanojević, at the University of Belgrade - School of Electrical Engineering, Belgrade, Serbia. JuliaCAP is written in Julia, a free open-source (MIT licensed) programming language. Whereas Julia is a relatively new language, there will be some words about it. As a free opensource software package, the underlining algorithm is revealed in full detail, so anybody can get a better understanding of the used methods. We offer JuliaCAP as a useful tool for solving linear time-invariant electric circuits. The future directives should be the improvement of simplifying expressions and the absence of the possibility to solve electric circuits in the complex domain of the Unilateral Laplace Transform. Also, it is shown through examples how this software operates. Electric circuits that are used in examples are Riordan gyrator network, 3rd order Butterworth Low-pass Filter, Subtractor and Adder.

The paper considers the basic concepts of a mathematical model. The connection between the model and reality and its place and relevance in the modern world is shown. The developed mathematical model of a servo pneumatic device, which includes an actuator and a proportional or discrete pneumatic valve, is presented. The basic equations describing the dynamics of the servo pneumatic device, boundary and initial conditions are given, which make it possible to analyze the stability of the drive. A non-linear object-oriented computer model of a pneumatic servo device is presented. The model is built in the form of block diagrams of equations that describe the relationship between the original physical quantities. The influence of the nature of the inductance of the electromagnet coil on the dynamic properties of the system is shown. The developed method for identifying the transfer function of pneumatic devices and its application in the preparation of mathematical models is presented. A technique for studying the stability of pneumatic systems has been created, based on establishing an unambiguous relationship between the experimentally obtained frequency characteristics of the pneumatic apparatus included in the system and the type of its transfer function. The form of transfer functions for the pneumatic devices under consideration is obtained. For the proportional pneumatic valves presented in the work, the quality indicators of transient processes in the time domain are formulated and determined, and the phase and amplitude margins are found. The criteria for the performance of pneumatic systems are formulated. The ratios for determining the described criteria are given. The boundaries of the operability of systems with a pneumatic drive have been established. The scientific novelty of the results presented in the work is that a non-linear object-oriented computer model of a servo pneumatic device has been created, unlike the existing ones, it is built in the form of block diagrams of equations that describe the relationship between the initial physical quantities, and has the principle of modularity. The model includes the transfer function of the control devices obtained using the developed method for identifying the parameters of the transfer function. This work is based and is implemented as a course of lectures of the course “Dynamics of Pneumatic drive”, is red by the author at the Bauman Moscow State Technical University at the Department of “Hydromechanics, Hydraulic Machines and Hydropneumoautomatics” (E10), as part of the preparation of masters in the specialty 05.04.13 – Hydraulic machines and hydropneumatic drives.

The paper deals with a new method for a sensitivity analysis in linear hybrid circuits. The circuits in view can contain elements with both lumped and distributed parameters when multiconductor transmission lines (MTL) play the role of their distributed parts. The technique is based on the modified nodal analysis (MNA) method serving to the basic description of the circuit. Firstly the frequency-domain sensitivities formulae are derived then the numerical inversion of Laplace transforms (NILT) is applied to obtain the time-domain sensitivities. In this paper a novel method for evaluation of sensitivities with respect to distributed parameters is elaborated while considering lossy nonuniform multiconductor transmission lines.

The challenge in terms of accurate prediction of electrical behavior, reliability and thermal management of semiconductor power devices goes through the coupling of multi physics analysis and especially through the coupling of nonlinear thermal models with nonlinear electrical models. In order to obtain a precise nonlinear thermal model which can be implemented as an equivalent SPICE (simulation program integrated circuits especially) subcircuit in circuit simulators, we present a methodology based on a model order reduction technique applied to a three dimensional finite element thermal description. This reduction method is based on the Ritz vector approach. In order to take into account the nonlinear thermal properties of materials, an extension of the method based on the Kirchoff transformation and an interpolation formula is proposed. This method, theoretically suitable only for homogeneous structures, exhibits in practice a very good accuracy for heterogeneous structures. Another improvement in the nonlinear transient response relies on the self consistent calculation of a coefficient related to the thermal conductivity approximation law. Thus, obtaining directly in time domain a nonlinear thermal reduced model for inhomogeneous structure is possible. The complete model has been successfully implemented in circuit simulator for several power devices and for various nonlinear materials such as GaAs, GaN or silicon. The nonlinear behavior has been validated on a wide range of input power and baseplate temperature. The influence of the interpolation formula is discussed for strongly nonlinear materials. Thermal infrared and electrical measurements have been performed to validate the simulation results