Interactive compact device modelling using Qucs equation‐defined devices

Recent trends in compact device modelling and circuit simulation suggest a growing movement towards standardization of Verilog‐A as a vehicle for semiconductor device specification and model interchange among commercial and open source simulators. This paper introduces a nonlinear equation‐defined device (EDD) characterized by current, voltage and charge equations with a similar syntax to Verilog‐A. The EDD has been implemented in Qucs and used extensively as a central feature in an interactive modelling system that allows straightforward prototyping of compact device models prior to translation into Verilog‐A. To illustrate the properties and the use of the Qucs EDD a number of examples centred on well‐known SPICE models are described. Copyright © 2008 John Wiley & Sons, Ltd.     

Why‐ and how‐ to integrate Verilog‐A compact models in SPICE simulators

This article presents a fast and accurate way to integrate and validate Verilog‐A compact models in SPICE‐like simulators. Modifications in the models' Verilog‐A source code may be required prior to their conversion into low‐level C language by a code generator. The most common of these modifications is discussed. The generated C code is then directly compiled in the target simulator resulting in an equivalent SPICE model. The comparison between Verilog‐A and SPICE models in the same simulation environment, for simple and complex circuits, validates the procedure. Performance tests for demanding designs are carried out for both models. Results highlight the higher simulation speed and lower memory consumption of SPICE models. Copyright © 2012 John Wiley & Sons, Ltd.     

A tabular source approach to modelling and simulating device and circuit noise in the time domain

Simulation of device and circuit noise at low frequencies is often carried out as part of a small‐signal ac analysis. Moreover, circuit simulators with rf analysis capabilities usually specify circuit performance in terms of S parameters and model high‐frequency noise in terms of noise waves and correlation matrices. It is also unusual to find circuit simulators that extend noise simulation to the time domain. This is particularly true for software packages developed from SPICE 2g6 or 3f5. This paper introduces a simple tabular noise source technique, which adds time‐domain noise to semiconductor device models and integrated circuit macromodels. The proposed technique is suitable for use with any general purpose circuit simulator. To demonstrate the power of the suggested approach the text describes time‐domain noise extensions to the SPICE diode, BJT, JFET, MOSFET and MESFET models. These noise extensions have been implemented and tested with the ‘Quite universal circuit simulator’ (Qucs). Copyright © 2011 John Wiley & Sons, Ltd.     

Implementation of the symmetric doped double‐gate MOSFET model in Verilog‐A for circuit simulation

Recently we developed a model for symmetric double‐gate MOSFETs (SDDGM) that, for the first time, considers the doping concentration in the Si film in the complete range from 1×10¹⁴ to 3×10¹⁸ cm⁻³. The model covers a wide range of technological parameters and includes short channel effects. It was validated for different devices using data from simulations, as well as measured in real devices. In this paper, we present the implementation in Verilog‐A code of this model, which allows its introduction in commercial simulators. The Verilog‐A implementation was optimized to achieve reduction in computational time, as well as good accuracy. Results are compared with data from 2D simulations, showing a very good agreement in all transistor operation regions. Copyright © 2009 John Wiley & Sons, Ltd.     

A matrix pencil approach to the local stability analysis of non‐linear circuits

This paper addresses local stability issues in non‐linear circuits via matrix pencil theory. The limitations of the state–space approach in circuit modelling have led to semistate formulations, currently framed within the context of differential‐algebraic equations (DAEs). Stability results for these DAE models can be stated in terms of matrix pencils, avoiding the need for state–space reductions which are not advisable in actual circuit simulation problems. The stability results here presented are applied to electrical circuits containing non‐linear devices such as Josephson junctions or MOS transistors. Copyright © 2004 John Wiley & Sons, Ltd.     

A step‐by‐step approach to compute a consistent initialization for the MNA

One of the difficulties of the numerical integration methods for differential–algebraic equations (DAEs) is the computation of consistent initial values before starting the integration, i.e. calculating values that satisfy the given algebraic constraints as well as the hidden constraints if higher index problems are considered. This paper presents an approach to calculate consistent initial values for index‐2 DAEs starting up from possibly inconsistent ones for systems arising from modified nodal analysis (MNA) in circuit simulation. This article is based on the results from Estévez Schwarz and Tischendorf, International Journal of Circuit Theory and Applications 2000; 28 : 131–162. Several of the denotations and results that we use were introduced there in more detail. Copyright © 2001 John Wiley & Sons, Ltd.     

A closed‐form equation approach to multi‐port/multi‐zone behavioral modeling of GaN FET Amplifiers

In this paper, a systematic method for the simulation of weakly and mildly nonlinear GaN FET amplifiers is reported. The core of the proposal is a third‐order Volterra‐based behavioral model with multi‐spectral and multi‐node capabilities that is formally derived from a circuit‐level representation. Starting with the equivalent circuit of a typical FET device with thermal power feedback and fading memory, described in terms of its large‐signal functions, closed‐form expressions for the kernels at the gate, drain and thermal nodes are developed up to the third order. The use of these kernels allows the calculation of the responses in the dc, first‐, second‐ and third‐harmonic zones, which are shown to be dependent on the frequency response of the amplifier circuit terminating impedances and thermal filter. The simulation approach has been applied to calculate the nonlinear response of a typical power amplifier circuit, showing the ability of the proposed approach to provide an accurate prediction of multi‐spectral, multi‐node, multi‐bias characteristics, including AM/AM‐AM/PM conversion, spectral regrowth, intermodulation, and temperature rise, under diverse input signal waveforms and bandwidths. These results have been successfully compared with commercial CAD tools based on harmonic balance or envelope simulation. Copyright © 2014 John Wiley & Sons, Ltd.     

A measurement‐based approach with accuracy evaluation and its applications to circuit analysis and synthesis

In this paper, we evaluate a useful general model for linear direct current (DC) networks, containing design parameters, multiple inputs and outputs. The outputs are rational multivariate functions of the parameters and linear functions of the inputs. For an unknown linear system, the unknown coefficients of these functions can be determined by taking a suitable number of measurements and solving a set of linear equations constructed from selected measurement data. The rational functions are useful to support the design such that outputs can be constrained to a desired interval. An interesting result was the particular case where the parameter varied is located at the output terminal. This is an alternative way to estimate the Thévenin equivalent of a circuit. Real data are in general noisy with accuracy dependent on the tolerance of components and on the measurement device used. We present a detailed analysis of the application of the measurement‐based approach under real experiments. Initially, a resistive DC circuit case is presented, and the results are verified by simulation and experimental laboratory data. Finally, practical circuits, such as a conditioning signal stage with an operational amplifier, and a boost DC–DC converter are considered. Copyright © 2017 John Wiley & Sons, Ltd.     

Improvement of high‐voltage impulses in track circuits with Kasami and LS codes

Track circuit systems based on high‐voltage impulses (HVI) have already been used in China to detect the state of track sections. With the demand for more reliable intelligent transportation systems in recent years, new advances, improvements, and innovations are being applied to their development. This work defines a HVI track circuit based on the encoding of the transmitted signal. Not only 15‐bit and 63‐bit Kasami sequences but also 19‐bit and 71‐bit loosely synchronized codes are applied to encode simultaneous HVI transmissions from 2 emitters. Train occupancy in different parts of the track section is also considered. The quality of the detection is evaluated by means of the correlation bounds. Furthermore, a simulation model for double‐track railways has been developed, which can be dedicated to the evaluation of a suitable signal processing in the track circuit under study. Compared to previous HVI track circuits, as a novelty, this work proposes the use of encoded transmissions to these track circuits, to improve their performance in terms of scanned distance and detection accuracy. The correlation properties of the sequences involved also make feasible to avoid any synchronization link between emitters and receivers, thus providing a significant advantage for later deployment.     

A new control strategy with fault ride‐through capability for VSC‐based offshore high power oil pump motor power supply system

In offshore oil platforms, high voltage and power motors (HV motors) are needed when transporting oil to the land. Traditional platform diesel generators cannot support so much power, so the required system must be supplied by the onshore AC grid. In general, when there is a long distance between the offshore platform and the shore, a DC transmission system is more efficient. This paper proposes a power supply approach for these motors using a voltage source converter (VSC) and derives the mathematical model for it. This method combines motor drive theory and studies in DC transmission field. Compared with the traditional motor control, this method, which makes full use of the advantages of VSC, can simplify the control strategy. And by using the Q–U droop characteristic, the strategy improves the system stability and fault ride‐through capability. Simulation is carried out in PSCAD/EMTDC, and the results verify the validity of the control method. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.