The thesis describes different between any signal and audio signal from the used amplifier´s quality point of view. There are mentioned ways of origin of distortions and their effect on the audio signal quality. There is also described in detail the principal of operational amplifier, it´s circuit realization and ways to improve the circuit topology in order to reach the best qualities. Choice of parts used for discreet realization of operational amplifier is consulted. Last but not least the thesis contents the practical part, stating the reasons for realization of operational amplifiers from discreet parts and also describing two most commonly used topologies of operational amplifiers. Their discreet version is designed and there are compared the different between the manufacturer’s data and the data measured during the simulation.

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Denna uppsats har formen av en essä. Syftet var att inom kompositionsprocessen synliggöra och studera viktiga parametrar och utvecklingsområden, samt jämföra resultatet mellan avsikten, slutresultatet av kompositionen och det som hände där emellan. Kompositionerna som har legat till grund för arbetet är två stycken för storband och ett stycke för tenorsaxofon och kammarensemble. Styckena och den kreativa processen analyseras utifrån ett personligt kompositionsperspektiv och resultatet visar att det genom målmedvetet arbete är möjligt att utveckla sin teknik och speciella beståndsdelar. Slutsatsen är att det går att förändra väl rotade vanor om man önskar det men att det kräver tid, mod och engagemang. / This master thesis has been written in the form of an essay. The purpose has been to unfold important parameters within the compositional process and to reflect upon how various parameters developed during this process. Additionally, it has been my aim to evaluate the results with respect to my intentions. Three compositions were analyzed. Two pieces for big band and one piece for tenor saxophone and chamber ensemble. The compositions and the creative process were analyzed from the composer's view. The result shows that it has been possible to develop my own compositional technique and various personal ingredients through deliberate practise of my compositional skills. My conclusion is, that if one wishes to change deep-rooted habits, it is possible to develop new habits, however, these matters require patience, commitment, as well as as fearlessness. / <p>Konserten blev uppskjuten pga coronaviruset (Covid-19)</p><p>Kompositioner för storband, Erika Hammarberg</p><p>Humboldt</p><p>The Crossing</p><p>Paso Doble </p><p>Berget</p><p></p><p></p>

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Diese Dissertation behandelt schwache Nichtlinearitäten in Radiofrequenzschaltern, die auf Grundlage von CMOS-Transistoren realisiert werden. Der besondere Schwerpunkt liegt auf der analytischen Modellierung sowie der Simulation der Nichtlinearität mithilfe einer TCAD (Technology Computer-Aided Design) Software. Die Nichtlinearität kann nach den verschiedenen Quellen klassifiziert werden: der Transistornichtlinearität und der Substratnichtlinearität. Für beide Bereiche werden umfassende Simulationen und analytische Modellierungen sowie Messungen präsentiert und interpretiert. / This dissertation treats weak nonlinearities in radio frequency switches that are realised based on CMOS transistor technology. A special focus lies on the analytical modeling and TCAD simulation of the nonlinearity. The nonlinearity is sorted into substrate and transistor nonlinearity. For both nonlinear regions profound simulations, analytical modeling and measurements are presented and interpreted.

In today's digital world, information and communication technology accounts for 3% and 2% of the global power consumption and CO2 emissions respectively. This alarming figure is on an upward trend, as future telecommunications systems and handsets will become even more power hungry since new services with higher bandwidth requirements emerge as part of the so called ¿future internet¿ paradigm. In addition, the mobile handset industry is tightly coupled to the consumer need for more sophisticated handsets with greater battery lifetime. If we cannot make any significant step to reducing the energy gap between the power hungry requirements of future handsets, and what battery technology can deliver, then market penetration for 4G handsets can be at risk. Therefore, energy conservation must be a design objective at the forefront of any system design from the network layer, to the physical and the microelectronic counterparts. In fact, the energy distribution of a handset device is dominated by the energy consumption of the RF hardware, and in particular the power amplifier design. Power amplifier design is a traditional topic that addresses the design challenge of how to obtain a trade-off between linearity and efficiency in order to avoid the introduction of signal distortion, whilst making best use of the available power resources for amplification. However, the present work goes beyond this by investigating a new line of amplifiers that address the green initiatives, namely green power amplifiers. This research work explores how to use the Doherty technique to promote efficiency enhancement and thus energy saving. Five different topologies of RF power amplifiers have been designed with custom-made signal splitters. The design core of the Doherty technique is based on the combination of a class B, class AB and a class C power amplifier working in synergy; which includes 90-degree 2-way power splitter at the input, quarter wavelength transformer at the output, and a new output power combiner. The frequency range for the amplifiers was designed to operate in the 3.4 - 3.6 GHz frequency band of Europe mobile WiMAX. The experimental results show that 30dBm output power can be achieved with 67% power added efficiency (PAE) for the user terminal, and 45dBm with 66% power added efficiency (PAE) for base stations which marks a 14% and 11% respective improvement over current stateof- the-art, while meeting the power output requirements for mobile WiMAX applications.

High efficiency is an essential requirement for any system, where the energy can be saved with full retention of system performance. The power amplifier in modern mobile communications system consumes most of the supplied power through the dissipated power and the required cooling systems. However, as new services were added as features for the developed mobile generations, the required data rate has increased to fulfil the new requirements. In this case, the data should be sent with the allocated bandwidth, so complex modulation schemes are used to utilise the available bandwidth efficiently. Nevertheless, the modulated signal will have a Peak to Average Power Ratio (PAPR) which increases as the modulation complexity is increasing. In this case, the power amplifier should be backed off and designed to provide good linearity and efficiency over high PAPR. Among the efficiency enhancement techniques, the Doherty technique (Load modulation technique) is the simplest one, where no additional circuity nor signal processing is required. In this work, the theory of load modulation amplifiers is investigated through two asymmetrical Doherty Power Amplifiers (DPA) targeting 3.3-3.5 GHz were designed and fabricated using two transistors (25 W and 45 W). In addition, more compact load modulation amplifiers targeting sub 6-GHz bandwidth of 5G specifically 3.4-3.8 GHz is discussed including the theory of implementing these amplifiers, where different amplifier capabilities are explored. Each amplifier design was discussed in detail, in which the input and output matching networks were designed and tested in addition to the design of the stability circuit to make sure that the amplifier is stable and working according to the specified requirements. The fabricated circuits were evaluated practically using the available instrument test, whereas Microwave Office software was used for the simulation purpose, each amplifier was designed separately, where all the designed amplifiers were able to provide the targeted efficiency at different back-off power points. Besides, some additional factors that affect the designed load modulation amplifiers such as the effect of the harmonics at the back-off and mismatching the amplifier is discussed. / European Union’s Horizon 2020 research and innovation programme (SECRET)

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The general trend of efficiency increase, weight and noise reduction has derived in the design of more slender, loaded, and 3D shaped blades. This has a significant impact on the stability of fan, and low pressure turbine blades, which are more prone to aeroelastic phenomena such as flutter. The flutter phenomenon is a self-excited, self-sustained unstable vibration produced by the interaction of flow and structure. These working conditions will induce either blade overload, or High Cycle Fatigue (HCF) produced by Limited Cycle Oscillation (LCO). The main objectives of the present work are on the investigation of the aeroelastic properties of a high-lift low-pressure in the light of the local flow features present in such profiles, in nominal and extreme off-design conditions both in high and low subsonic Mach number, for three dif-ferent rigid body modes. In addition, the validity of the linearity assump-tion of the influence coefficient technique has also been investigated, in order to expand the understanding of the physical limits of this assumption. This work has been designed as experimental investigation in the influence coefficient domain focused on a high-lift low-pressure turbine designed by ITP within the framework of the European FP7 project FU-TURE. These experiments have been carried out in the Aeroelastic test rig (AETR), at KTH Stockholm, which consist of an instrumented annular sector cascade with a single oscillating blade. The results acquired have been supported by numerical results provided by a non-propietary commercial software package (ANSYS CFX). The results suggest that the typical three-dimensional effects associated secondary flow features and tip leakage flows have a significant influence on the aeroelastic performance and the cascade stability. However the major influence appears as a consequence of the separation surface on the pressure side which appears at extreme off-design operating conditions. The contribution to stability of this local feature depend on the oscillation mode showing for the axial and torsion mode a neutral stability contribution, which is directly associated with the geometrical properties of the cascade. However, on the circumferential mode this separation surface has a stabilizing effect much more independent of the blade geometry. The study of the linearity assumption of the influence coefficient domain has revealed, that an apparent linear relation between the integrated unsteady response and the vibrational amplitude, does not necessary imply that the local unsteady response is linear with respect to the oscillation amplitude. The results also suggest that the validity of the linearity as-sumption is more sensitive to high oscillation amplitudes at high Mach conditions. / <p>QC 20140609</p>

With the growing load demand, Ultra high Voltage (UHV) transmission lines are utilized in many countries around the world for bulk power transmission from remote locations over long distance. UHV transmission lines have typical features and it poses a challenge to the power system design with respect to protection, insulation and reactive power compensation, etc. Protection is a key issue in UHV transmission since a relay failure can interrupt and damage the power system. There are distance and differential protection schemes in the transmission line which account for security of the power system.  This thesis report is based on analysis carried out to find out the typical features associated with the UHV transmission systems. Also the impacts of the UHV transmission line characteristics on line distance protection scheme are observed. The traditional distance relays based on the lumped line parameters are not suited for the UHV transmission lines of very long distances. In this case a simulation is carried out for a 765 kV transmission system modeled in PSCAD. In such a case the non-linearity is even more prominent and the relay is less dependable. In line with the simulation and the analysis for the challenges in UHV transmission system, it is observed that the fault impedance of the line is non-linear and this non-linearity causes the failure of relay operation for a fault location at the boundary of the zone of protection. The fault simulation was carried out in PSCAD and the quadrilateral distance relay characteristics were plotted using MATLAB. From the simulation and results, it is finally concluded that traditional distance protection relays with lumped parameter line modeling is not suitable for UHV transmission liens due to non-linearity in fault impedance and it leads to relay failure. / Ultra high voltage (UHV) transmissionsledningar används i många länder till följd av ett växande behov av överföra hög effekt från avlägset belägna produktionsanläggningar till konsumenter. UHV-transmissionsledningar har speciella egenskaper som innebär utmaningar vid designandet av kraftsystem. Några utmaningar är systemskydd, isolation, och reaktiv effektkompensering. Systemskydd är en viktig aspekt för UHV-transmission eftersom haveri av reläskydd kan orsaka driftstopp och även skada ett kraftsystem. Det finns distans- och differentialskydd i transmissionsledningar som utgör skydd för kraftsystemet.  Denna avhandling är baserad på analyser som har utförts för att åskådliggöra de typiska egenskaperna som är sammankopplade med UHV-transmissionssystem. Även inverkan på distansskydd orsakad av karaktäristiken av UHV-transmissionsledningar utvärderas. De traditionella distansreläskydden som baseras på de sammanslagna ledningsparametrarna är inte lämpade för UHV-transmissionsledningar som stäcker sig över långa avstånd. I detta fall har en simulering utförts i PSCAD för ett transmissionssystem med spänningen 765 kV. I ett sådant fall är karaktäristiken ännu mer olinjär och reläskydden ännu mindre pålitliga. Det observeras att felimpedansen för ledningen är olinjär och till följd av detta orsakas problem med reläskydden då ett fel uppkommer vid utkanten av den skyddade zonen. Denna observation överensstämmer med simuleringarna och de förväntade utmaningarna kopplade till UHV. Simuleringar av felfall utfördes i PSCAD och karaktäristiken av reläskydden plottades med hjälp av MATLAB. Från resultat presenteras i rapporten, konkluderas det att konventionella distansskyddsreläer med modellering av sammanslagna ledningsparametrar inte är lämpliga för UHV-transmissionsledningar på grund av att den olinjära felimpedansen leder till att reläskydden havererar.