Qucs Frequency Domain Non-Linear Compact Modelling and Simulation of IC Spiral Inductors on Silicon

SPICE AC circuit simulation is fundamentally a small signal network analysis of linear or non-linear circuits operating at specified DC bias conditions, where the circuit component values are assumed not to be functions of AC input signal frequency. In the case of RF circuit simulation this assumption can give rise to significant modelling errors. With the recent improvementsinGeneralPublicLicense(GPL)circuitsimulators thissituationischanging,particularlythroughtheintroductionof Frequency Dependent Equation-Defined Device (FEDD) models, non-linear current/voltage static and dynamic Equation-Defined Device (EDD) models and user controlled swept signal frequency simulation employing Harmonic Balance steady state analysis. The main purpose of this paper is to introduce a number of novel modelling and circuit simulation techniques that allow, and enhance, the construction of compact device models with embedded behavioural components whose non-linear properties are functions of AC input signal frequency. To demonstrate these new modelling techniques a compact model for a 10 GHz band width spiral inductor integrated on silicon is introduced, its compact model presented, and finally its simulation performance compared with published measured device data

Frequency domain non-linear compact modelling and simulation of IC spiral inductors on silicon

SPICE AC circuit simulation is fundamentally a small signal network analysis of a linear or non-linear circuit operating at specified DC bias conditions, where the electrical network component values are assumed not to be functions of AC input signal frequency. In the case of RF circuit simulation this assumption can give rise to significant modelling errors.With the recent improvements in General Public License (GPL) circuit simulators this situation is changing, particularly through the introduction of Frequency Dependent Equation-Defined Device (FEDD) models, non-linear current/voltage static and dynamic Equation-DefinedDevice(EDD)modelsandusercontrolledswept signal frequency simulation employing Harmonic Balance steady state analysis. The main purpose of this paper is to introduce a number of novel modelling and circuit simulation techniques that allow, and enhance, the construction of compact device models with embedded behavioural components whose non-linear properties are functions of AC input signal frequency. To demonstrate these new modelling techniques a compact model for a 10 GHz band width spiral inductor integrated on silicon is introduced, its compact model presented, and finally its simulation performance compared with published measured device data

Improvements in Qucs-S Equation-Defined Modelling of Semiconductor Devices and IC’s

The Qucs Equation-Defined Device was introduce roughly ten years ago as a versatile behavioural simulation component for modelling the non-linear static and dynamic properties of passive components, semiconductor devices and IC macromodels. Today, this component has become an established element for building experimental device simulation models. It’s inherent interactive properties make it ideal for device and circuit modelling via Qucs schematics. Moreover, Equation-Defined Devices often promote a clearer understanding of the factors involved in the construction of complex compact semiconductor simulation models. This paper is concerned with recent advances in Qucs-S/Ngspice/XSPICE modelling capabilities that improve model construction and simulation run time performance of Equation-Defined Devices using XSPICE model syntheses. To illustrate the new Qucs-S modelling techniques an XSPICE version of the EPFL EKV v2.6 long channel transistor model together with other illustrative examples are described and their performance simulated with Qucs-S and Ngspice

Qucs-S help documentation release 0.0.21-S

Following the release of Qucs-0.0.18 in August 2014 the Qucs Development Team considered in detail a number of possible directions that future versions of the software could take. Spice4qucs is one of these routes. It addresses a number of problems observed with the current version of Qucs while attempting to combine some of the best features of other GPL circuit simulation packages. The project also aims to add additional model development tools to those currently available in Qucs-0.0.18. Qucs was originally written as an RF and microwave engineering design tool which provided features not found in SPICE, like S parameter simulation, two and multiport small signal AC circuit analysis and RF network synthesis. Since it was first release under the General Public License (GPL) in 2003 Qucs has provided users with a relatively stable, flexible and reasonably functional circuit simulation package which is particularly suited to high frequency circuit simulation. In the years following 2003 the Qucs Development team added a number of additional simulation facilities, including for example, transient simulation, device parameter sweep capabilities and single tone Harmonic Balance simulation, making Qucs functionality comparable to SPICE at low frequencies and significantly extended at high frequencies. Considerable effort has also been made to improve the device modelling tools distributed with Qucs. The recent versions of the software include code for algebraic equation manipulation, Equation-Defined Device (EDD) modelling, Radio Frequency Equation-Defined Device (RFEDD) simulation and Verilog-A synthesised model development plus a range of compact and behavioural device modelling and post simulation data analysis tools that have become central features in an open source software package of surprising power and utility. One of the most often requested new Qucs features is “better documentation”, especially documentation outlining the use and limitations of the simulation and the modelling features built into Qucs. Qucs is a large and complex package which is very flexible in the way that it can be used as a circuit design aid. Hence, however much documentation is written describing its functionality there are always likely be simulation and modelling examples that are missing from the Qucs documentation. In future Qucs releases will be accompanied by two or more basic Qucs documents. The first of these, simply called “Qucs-Help”, provides introductory information for beginners and indeed any other users, who require help in starting to use Qucs. The second Qucs document, called “Spice4qucs-Help”, introduces more advanced simulation and modelling topics. Both documents present a large number of typical circuit simulation and compact device modelling examples

Recent developments in Qucs-S equation-defined modelling of semiconductor devices and IC’s

The Qucs Equation-Defined Device was introduce roughly ten years ago as a versatile behavioural simulation component for modelling the non-linear static and dynamic properties of passive components, semiconductor devices and IC macromodels. Today, this component has become an established element for building experimental device simulation models. It’s inherent interactive properties make it ideal for device and circuit modelling via Qucs schematics. Moreover, Equation-Defined Devices often promote a clearer understanding of the factors involved in the construction of complex compact semiconductor simulation models. This paper is concerned with recent advances in Qucs-S/Ngspice/XSPICE modelling capabilities that improve model construction and simulation run time performance of Equation-Defined Devices using XSPICE model syntheses. To illustrate the new Qucs-S modelling techniques an XSPICE version of the EPFL EKV v2.6 long channel transistor model together with other illustrative examples are described and their performance simulated with Qucs-S and Ngspice

Circuit design techniques for Power Efficient Microscale Energy Harvesting Systems

Power Management is considered one of the hot topics nowadays, as it is already known that all integrated circuits need a stable supply with low noise, a constant voltage level across time, and the ability to supply large range of loads. Normal batteries do not provide those specifications. A new concept of energy management called energy harvesting is introduced here. Energy harvesting means collecting power from ambient resources like solar power, Radio Frequency (RF) power, energy from motion...etc. The Energy is collected by means of a transducer that directly converts this energy into electrical energy that can be managed by design to supply different loads. Harvested energy management is critical because normal batteries have to be replaced with energy harvesting modules with power management, in order to make integrated circuits fully autonomous; this leads to a decrease in maintenance costs and increases the life time. This work covers the design of an energy harvesting system focusing on micro-scale solar energy harvesting with power management. The target application of this study is a Wireless Sensor Node/Network (WSN) because its applications are very wide and power management in it is a big issue, as it is very hard to replace the battery of a WSN after deployment. The contribution of this work is mainly shown on two different scopes. The first scope is to propose a new tracking technique and to verify on the system level. The second scope is to propose a new optimized architecture for switched capacitor based power converters. At last, some future recommendations are proposed for this work to be more robust and reliable so that it can be transfered to the production phase. The proposed system design is based on the sub-threshold operation. This design approach decreases the amount of power consumed in the control circuit. It can efficiently harvest the maximum power possible from the photo-voltaic cell and transfer this power to the super-capacitor side with high efficiency. It shows a better performance compared to the literature work. The proposed architecture of the charge pump is more efficient in terms of power capability and knee frequency over the basic linear charge pump topology. Comparison with recent topologies are discussed and shows the robustness of the proposed technique

UHF-sagedusala sidesüsteem kuupsatelliidile

Communication is one of the most important parts of any satellite. Estonian future satellite ESTCube-2 needs a new and advanced communication system to upload commands and firmware and download telemetry and images. The goal of this masters thesis was to determine system architecture and develop first electrical prototype of this communication system. Strengths and weaknesses of previous systems was researched and new system design was determined. Necessary single components were determined. Single components were built to prototypes, tested and characterised. RF parameters of filters were measured and found to be suitable for the system. Components were integrated to a first electrical model of the communication system. All of the work meets the requirements set to the system. Since power is very limited on small satellites focus was making the communication system energy efficient. This work could not be done without support from people in ESTCube team. Most of the necessary knowledge was taught by supervisors. Much of supporting work was done by other members of communication subsystem team – Ahti Laurisson, Taavi Adamson and Laur Joost. Work on the system continues in to develop full software and test all the component integration. This work contains technical drawings and description of developed system. It also provides information for developing other similar systems

The Qucs/QucsStudio and Qucs-S graphical user interface: an evolving “white-board” for compact device modeling and circuit simulation in the current era

The Qucs/QucsStudio and Qucs-S simulators share a common graphical user interface which has slowly evolved into an interactive platform for drawing circuit schematics, controlling simulation and displaying simulation output data and measured device/circuit parameters/properties. This interface acts as a window for accessing circuit simulation software and is in many ways similar to the “White-Boards” that are popular among scientists and engineers for recording ideas when “brainstorming” circuit design or analysis problems. This paper outlines the evolution of the Qucs device modeling and simulation “white-Board” from concept to working media over the fifteen year period that Qucs, QucsStudio and Qucs-S have been under development. The operation of a number of the “White-Board” features are introduced with a compact tunnel diode model and the simulation data obtained from tests using the QucsStudio and Qucs-S software packages

PCB Design and Fabrication for NEMS Applications

In this project, a resonator was theoretically defined and modelled in an effort to choose appropriate impedance matching between the resonator and outside electronics. Quite Universal Circuit Simulation (QUCS) was used to model the S-parameter of potential electronic circuits. Two types of impedance were tested: LC and transformer. Based on the commercial availability of the components and the S-parameter results, a 3 transformer matching design was chosen. The schematic library and the PCB library of all the components were made on Altium and a first design of the PCB is presented

Doctor of Philosophy

dissertationIn Chapter 1, an introduction to basic principles or MRI is given, including the physical principles, basic pulse sequences, and basic hardware. Following the introduction, five different published and yet unpublished papers for improving the utility of MRI are shown. Chapter 2 discusses a small rodent imaging system that was developed for a clinical 3 T MRI scanner. The system integrated specialized radiofrequency (RF) coils with an insertable gradient, enabling 100 'm isotropic resolution imaging of the guinea pig cochlea in vivo, doubling the body gradient strength, slew rate, and contrast-to-noise ratio, and resulting in twice the signal-to-noise (SNR) when compared to the smallest conforming birdcage. Chapter 3 discusses a system using BOLD MRI to measure T2* and invasive fiberoptic probes to measure renal oxygenation (pO2). The significance of this experiment is that it demonstrated previously unknown physiological effects on pO2, such as breath-holds that had an immediate (<1 sec) pO2 decrease (~6 mmHg), and bladder pressure that had pO2 increases (~6 mmHg). Chapter 4 determined the correlation between indicators of renal health and renal fat content. The R2 correlation between renal fat content and eGFR, serum cystatin C, urine protein, and BMI was less than 0.03, with a sample size of ~100 subjects, suggesting that renal fat content will not be a useful indicator of renal health. Chapter 5 is a hardware and pulse sequence technique for acquiring multinuclear 1H and 23Na data within the same pulse sequence. Our system demonstrated a very simple, inexpensive solution to SMI and acquired both nuclei on two 23Na channels using external modifications, and is the first demonstration of radially acquired SMI. Chapter 6 discusses a composite sodium and proton breast array that demonstrated a 2-5x improvement in sodium SNR and similar proton SNR when compared to a large coil with a linear sodium and linear proton channel. This coil is unique in that sodium receive loops are typically built with at least twice the diameter so that they do not have similar SNR increases. The final chapter summarizes the previous chapters