Qucs: a GPL software package for circuit simulation, compact device modeling and circuit macromodeling from DC to RF and beyond

Qucs is an open source circuit simulator with extensive device and circuit modeling capabilities. It is one of the GPL simulators supporting VerilogA compact model standardization. Versions are available for most of the popular computer operating systems. The package is equipped with a range of device and modeling features which allow fast prototyping of experimental compact device and circuit macromodels. These include, traditional subcircuits, equation defined devices and Verilog-A compact models generated using the ADMS compiler. Recent improvements to the Qucs/ADMS interface now allow a well defined procedure for VerilogA model construction. This paper outlines the structure and simulation capabilities of the Qucs simulator. To illustrate the performance of this emerging GPL simulator a number of examples taken from DC to RF are described. The paper also presents a comparative study of photodiode model development using the different Qucs modelling techniques, and finally introduces a new compact macromodel, with equation monitoring capabilities, for the EKV 2.6 MOSFET model

Compact macromodelling of operational amplifiers with equation defined devices

A new approach to the design of operational amplifier macromodels, based on a multi-terminal non-linear equation defined device, is presented. The concept of a compact macromodel is introduced and demonstrated by the design of a general purpose operational amplifier macromodel. The new macromodel models the principle operational amplifier characteristics, plus a number of features not normally found in previously published macromodels, including common-mode range, differential gain reduction during output voltage saturation, power-supply current sensing and temperature effects. The performance of the new macromodel has been tested using the Qucs circuit simulator and has been found to perform well in comparison to other published operational amplifier macromodels

Qucs, SPICE and Modelica equation-defined modelling techniques for the construction of compact device models based on a common model template structure

Current releases of the popular Qucs GPL circuit simulator, the freely available LTspice IV simulator and the open source OpenModelica physical simulation package offer substantial compact semiconductor device modelling capabilities, including equation defined macromodelling facilities and access to either Verilog-A code or Modelica language compilers. This paper introduces a compact modelling technique based on a model template structure which exploits common hardware description language features found among a number of the current freely available simulation packages. An extended version of the standard SPICE diode model is used to demonstrate the power and modelling flexibility of the proposed template model. The cross-package modular approach to compact semiconductor device modelling presented in this paper also stresses the role new modelling techniques will take on as simulator technology evolves in the future

Advances in compact semiconductor device modelling and circuit macromodelling with the Qucs GPL circuit simulator

Advances in circuit simulation technology suggest a strong movement towards software packages which promote equation based compact semiconductor device model and circuit macromodel development. The Verilog-A subset of the Verilog- AMS hardware description language being a popular choice of hardware description language for model construction. The Qucs circuit simulator is one of the GPL software packages supporting the MOS-AK Verilog-A standardisation initiative. This paper outlines recent advances in Qucs equation based modelling techniques, including (1) Qucs equation defined device/Verilog-A compatibility improvements, (2) non-linear radio frequency equation defined device modelling techniques, (3) modelling non-linear physical processes, and (4) methods for construction Verilog-A models for established and new technologies. The paper also presents a number of examples which illustrate the capabilities of the Qucs model construction tools implemented by the Qucs development team

Interactive compact device modelling using Qucs Equation Devices (EDD)

The latest Qucs release marks a turning point in the development of the Qucs device and circuitmodeling facilities. Release 0.0.11 introduced component values defined by equations, and for the first time allowed subcircuits with parameters. Release 0.0.12 extends these features to add device model construction using symbolic equations that are similar to model code written in the Verilog-­A language. In designing the latest Qucs modeling features the Qucs team has attemptedto address the need to provide the package with an interactive and easy to use modeling systemthat allows fast compact device and circuit macromodel construction

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 done as part of 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)

A hybrid Verilog-A and equation-defined subcircuit approach to MOS switched current analog cell modeling and simulation in the transient and large signal ac domains

Conventional modeling and simulation of two phase switched current MOS integrated circuits is normally undertaken at semiconductor device level. This allows primary and secondary circuit effects to be studied and characterised. However, with the growing complexity of this type of circuit, transient domain simulation times can become prohibitively long, restricting the size of circuit that can be easily investigated. Measurable reductions in transient simulation run times can be achieved by modeling part, or all, of a switched current design as a macromodel. This paper introduces a hybrid approach to MOS switched current circuit modeling that combines the primary features of compact device modeling with functional circuit macromodeling. To illustrate the proposed hybrid modeling procedure the properties, and simulation model, of a MOS switched current analog memory cell are described. The material presented also demonstrates how recent trends in Quite universal circuit simulator (Qucs) technology promote embedded Verilog-A models and equation defined subcircuits as integral elements in mixed-mode circuit and system design

Follow-up of vestibular function in bilateral vestibulopathy

Objective: Bilateral vestibulopathy (BV) leads to a bilateral deficit of the vestibulo-ocular reflex and has various aetiologies. The main goal of this study was to determine the frequency and degree of recovery or worsening of vestibular function over time.Methods: 82 patients (59 males, 23 females; mean age at the time of diagnosis 56.3 (SD 17.6) years) were re-examined 51 (36) months after the first examination. All patients underwent a standardised neuro-ophthalmological and neuro-otological examination. Electronystagmography with bithermal caloric irrigation was analysed by measurement of the mean peak slow phase velocity (SPV) of the induced nystagmus. Patients evaluated the course of their disease in terms of balance, gait unsteadiness and health related quality of life.Results: Statistical analysis of the mean peak SPV of caloric induced nystagmus revealed a non-significant worsening over time (initial mean peak SPV 3.0 (3.5)°/s vs 2.1 (2.8)°/s). With respect to subgroups of aetiology, only patients with BV due to meningitis exhibited an increasing, but non-significant SPV (1.0 (1.4)°/s vs 1.9 (1.6)°/s). Vestibular outcome was independent of age, gender, time course of manifestation and severity of BV. Single analysis of all patients showed that a substantial improvement ⩾5°/s occurred in two patients on both sides (idiopathic n = 1, Sjögren's syndrome n = 1) and in eight patients on one side (idiopathic n = 6, meningitis n = 1, Menière's disease n = 1). In 84% of patients there was impairment of their health related quality of life (42% slight, 24% moderate, 18% severe). Forty-three per cent of patients rated the course of their disease as stable, 28% as worsened and 29% as improved.Conclusions: Our data support the view that more than 80% of patients with BV do not improve. Thus the prognosis of BV is less favourable than assumed

Qucs workbook

This document is intended to be a work book for RF and microwave designers.Our intention is not to provide an RF course, but some touchy RF topics. The goal is to insist on design rules and work flow for RF design using CAD programs. This work flow will be handled through different subjects

Inkjet- and flextrail-printing of silicon polymer-based inks for local passivating contacts

In this work innovative additive printing methods for formation of polycrystalline silicon (poly-Si) and polycrystalline silicon carbide (poly-SiC) layers of local tunnel oxide passivating contacts (TOPCon) is evaluated. Replacement of conventional vacuum processes and vapor-phase deposition by additive printing of Si in fabrication process of high efficiency solar cells reduces processing complexity, and, hence manufacturing costs. Reliable inkjet- and FlexTrail-printing processes are developed for liquid-phase polysilane and organic polysilazane inks that are precursors of Si and SiC, respectively. FlexTrail is introduced as a potential technology to print uniform closed thin films of polysilane free of ruptures. Moreover, from inkjet-printing of the developed polysilane ink, homogenous, closed and crack free thin films of poly-Si are obtained after high temperature annealing. The polysilane ink is formulated considering evaluation of several solvents and photoinduced polymerization conditions. Inkjet-printing process development and optimization according to high frequency rheological characterization of organic polysilazane (OPSZ) is presented. Printed thin films are characterized after high temperature annealing (T = 950 °C, t = 60 min) to be uniform and free of micro cracks