No description available.

Yes / In the design of phase shifters, the modeling equations are too complicated and require some approximations to be derived correctly by hand. In response to this problem, this paper presents a generalized concept, algorithm, and MATLAB code that provide the exact modeling equations of the transmission parameters and the scattering parameters of any 90^o wideband stub-loaded phase shifter. The proposed code gives the modeling equations in term of variables for any number of stubs and characteristic impedance value by utilizing the symbol-based analysis of the MATLAB. It also illustrates the results as a function of normalized frequency relative to the center frequency f_o, and can be and can be tailored to any user-defined frequency range. As a matter of comparison, a three-stub wideband 90^o stub-loaded phase shifter is simulated using CST Microwave Studio and experimentally fabricated on Rogers RT5880 dielectric substrate with dimensions of 30×40×0.8 〖mm〗^3. The comparison reveals the accuracy of the proposed computerized modeling with -10 dB impedance bandwidth equal to 90% (0.55 fo-1.45 fo), (90∓5 degrees ) phase difference bandwidth equal to 100% (0.5 fo-1.5 fo), and negligible insertion loss. The novelty of this work is that the proposed code provides the exact modeling equations of the stub-loaded phase shifter for any number of stubs regardless the complexity of the mathematical derivations.

Thermoacoustic instabilities are a problem in modern pre-mixed combustors causing reduced performance and leading in the extreme to combustor failure from excessive pressure cycles. Much work has been done using linear controllers to eliminate these instabilities. Many experimenters in the field have used pulsed and subharmonic fuel controllers to eliminate these instabilities, but very little investigative work has been done on these controllers. The goal of this work is to explain the mechanism of control behind pulsed controllers. It is shown that the combustion system can be treated as a linear system, thus meaning that frequency components of the control signal at the desired instability frequency are the dominant means of control, with nonlinear effects only serving to slightly reduce the gain necessary for control. Fourier analysis is thus performed on pulsed signals and the components analyzed, showing that there will indeed be a component of a pulsed signal at the frequency of the instability, aside from a few select cases. It is then proven that this frequency component is largely responsible for control of the thermoacoustic system using proportional height pulse train signals, which will change pulse height based on the amplitude of the instability. This analysis is then used to predict the height of instabilities resulting from the use of fixed height pulse control signals. Finally, numerical simulations and experimental observations support the analytical constructs. Acoustic control is mainly used for these experiments, although some preliminary work with liquid fuel controllers is also presented. / Master of Science

Lean premixed fuel-air conditions in large gas turbines are used to improve efficiency and reduce emissions. These conditions give rise to large undamped pressure oscillations at the combustor's natural frequencies which reduce the turbine's longevity and reliability. Active control of the pressure oscillations, called thermoacoustic instabilities, has been sought as passive abatement of these instabilities does not provide adequate damping and is often impractical on a large scale. Phase shift control of the instabilities is perhaps the simplest and most popular technique employed but often does not provide good performance in that controller induced secondary instabilities are generated with increasing loop gain. This thesis investigates the general underlying cause of the secondary instabilities and shows that high average group delay through the frequency region of the instability is the root of the problem. This average group delay is then shown to be due not only the controller itself but can also be associated with other components and inherent characteristics of the control loop such as actuators and time delay, respectively. An "optimum" phase shift controller, consisting of an appropriate shift in phase and a low order, wide bandwidth bandpass filter, is developed for a Rijke tube combustor and shown to closely match the response of an LQG controller designed only for system stabilization. Both the optimal phase shifter and the LQG controller are developed based on a modified model of the thermoacoustic loop which takes into account the change in density of the combustion reactants at the flame location. Additionally, the system model is coupled with a model of the control loop and then validated by comparison of simulated results to experimental results using nearly identical controllers. / Master of Science

Este trabalho, desenvolvido junto ao Grupo de Novos Materiais e Dispositivos (GNMD) pertencente ao Laboratório de Microeletrônica (LME) da Universidade de São Paulo, apresenta a modelagem de um defasador passivo miniaturizado com baixas perdas para aplicações em ondas milimétricas (mmW-milimeter waves). Este defasador é baseado em um conceito inovador utilizando sistemas micro-eletromecânicos (MEMS) distribuídos e linhas de transmissão coplanares de ondas lentas. Este conceito é proposto no projeto Jovem Pesquisador FAPESP (Processo no. 2011/18167-3), ao qual este projeto está vinculado. A defasagem neste tipo de dispositivo é conseguida pela liberação das fitas da camada de blindagem de uma linha de transmissão tipo S-CPW (Shielded-Coplanar Waveguide). As fitas liberadas podem ser movimentadas eletrostaticamente, o que praticamente não consome energia. Este projeto pretende projetar um defasador para fabricação com a tecnologia do Laboratório de Microeletrônica da Escola Politécnica da Universidade de São Paulo. Adicionalmente, este trabalho apresenta resultados experimentais de um processo de fabricação IN-HOUSE baseado na metodologia de integração por flip-chip. A tecnologia de integração implementada é baseada na soldagem de um chip sobre um substrato, no qual são construídos uma nova geração de pilares de cobre finos, cujo espaçamento entre pilares é menor que 100 ?m. Essa redução nas dimensões pode ser usada com a nova geração de dispositivos de comunicações na faixa das mmW. Em termos de fabricação, foram obtidos pilares de cobre altamente miniaturizados com uma altura significativa e uniforme que permite a integração com o chip. Além do mais, os resultados obtidos representam avanços significativos no processo de fabricação que será usado como tecnologia de integração híbrida em um interposer baseado em substrato de alumina nanoporosa (MnM-Metallic Nanowire Membrane). Esse interposer desempenha um papel indispensável no GNMD, já que atualmente estão sendo estudadas suas propriedades elétricas e já foram construídos dispositivos sobre o substrato com resultados promissores. / This work, performed at the New Materials and Devices Group (GNMD) of the Microelectronics Laboratory of the Polytechnic School of the University of São Paulo, presents the modeling of a miniaturized passive phase shifter with low losses for applications in millimeter waves. It is based on an innovated concept, which uses distributed MEMS phase shifters and slow-wave coplanar wave guides. Such concept is proposed under the FAPESP Youth Researcher project (Process number 2011/18167-3). The phase shifter on this kind of device is achieved by releasing the shielding layer of the Shielded-Coplanar Waveguide. The released ribbons are electrostatically displaced, which does not consume energy. The aim of this project is to design a phase shifter for fabrication with the technology available at the Microelectronics Laboratory. Additionally, this work presents experimental results of a flip-chip fabrication process. This technology is based on next generation of fine pitch copper pillar bumping, with pillar pitch of less than 100 ?m that support next generation of communication devices at the millimeter wave frequency range. From the fabrication point-of-view, highly miniaturized copper pillars with appropriate thicknesses were obtained. Furthermore, the results obtained represent a significant advance in the fabrication process that will be used as a hybrid integration technology on an interposer based on a nanoporous alumina substrate (MnM-Metallic Nanowire Membrane).

This work deals with problems where multiple actors simultaneously take control decisions and implement the corresponding actions in large multi-area power systems. The fact that those actions take place in the same transmission grid introduces a coupling between the various decision-making problems. First, transmission constraints involving all actors' controls must be satisfied, while, second, the satisfaction of an actor's operational objective depends, in general, not only on its own actions but on the others' too. Algorithms and/or operational procedures are, thus, developed seeking to reconcile the multiple actors' simultaneous decisions. The confidentiality and operational autonomy of the actors' decision-making procedures are preserved. In particular, two specific problems leading to such a multi-actor situation have been treated. The first is drawn from a recently emerging situation, at least in Europe, where several Transmission System Operators (TSOs) have installed and/or are planning to install Phase Shifting Transformers (PSTs) in such locations in their areas that, by properly adjusting the PST phase angle settings, they can significantly control the power flows entering and exiting their systems. A general framework is proposed for the control of PSTs owned by several TSOs, taking into account their interactions. The proposed solution is the Nash equilibrium of a sequence of optimizations performed by the various TSOs, each of them taking into account the other TSOs' control settings as well as operating constraints relative to the whole system. The method is applied to a linearized network model and illustrated on the IEEE 118-bus system. The second multi-actor situation dealt with in this work stems from the recently increasing amount of discussions and efforts made towards creating the right market structures and operational practices that would facilitate a seamless inter-area trade of electricity throughout large interconnections. In this respect, in accordance with European Union's goal of a fully functional Internal Electricity Market where ideally every consumer will be able to buy electric energy from every producer all across the interconnection, the possibility of every market participant to place its bid in whatever electricity market of an interconnection has been considered. This results in overlapping markets, each with its own schedule of power injections and withdraws, comprising buses all around the interconnection, that are cleared simultaneously by Transaction Schedulers (TSs). An iterative procedure is proposed to reconcile the various TS schedules such that congestion is managed in a fair and efficient way. The procedure converges to such schedules that the various TS market clearings are in a Nash equilibrium. The method is then extended towards several directions: enabling market participants to place their bids simultaneously in more than one TS's market, incorporating $N-1$ security constraints, allowing for joint energy-reserve dispatch, and, accounting for transmission losses. The corresponding iterative algorithms are thoroughly illustrated in detail on a 15-bus as well as the IEEE RTS-96 system.

A fully integrated CMOS 0 – 900 phase shifter in 0.18um TSMC technology is presented. With the increasing use of wireless systems in GHz range, there is high demand for integrated phase shifters in phased arrays and MIMO on chip systems. Integrated phase shifters have quite a high number of integrated inductors which consume a lot of area and introduce a huge amount of loss which make them impractical for on chip applications. Also tuning the phase shift is another concern which seems difficult with use of passive elements for integrated applications. This work is presents a new method for implementing phase shifters using only active CMOS elements which dramatically reduce the occupied area and make the tuning feasible. Also a fully integrated millimeter-wave VCO is implemented using the same technology. This VCO can be part of a 24 GHz frequency synthesizer for 24 GHz ISM band transceivers. The 24 GHz ISM band is the unlicensed band and available for commercial communication and automotive radar use, which is becoming attractive for high bandwidth data rate.

Ferrite phase shifters are key components of passive phased array antenna systems. In a modern radar system, microwave components in the transmit path should handle high microwave power levels. Also low loss operation in phase shifters is critical, since radar range depends on the microwave power transmitted from the antennas. In this respect, ferrite phase shifters provide required performance characteristics for phased array radar systems. In this thesis, Reggia-Spencer type and twin-toroid type ferrite phase shifters operating at X-Band are designed, simulated, fabricated and measured. Measurements of the fabricated ferrite phase shifters are compared with simulation results. Electromagnetic simulations are performed using CST.

Die vorliegende Arbeit ist der analytischen Untersuchung und Weiterentwicklung von Methoden und Schaltungen zur Einstellung der Signalphase und -amplitude gewidmet. Hierbei wird zum Ziel gesetzt, die Leistungsfähigkeit dieser Schaltungen als analoge Hochfrequenz-Baugruppen in Empfangs- und Sendeschaltkreisen mit einem vergleichbaren oder geringerem schaltungstechnischen Aufwand und Strombedarf zu verbessern und dies anhand von Implementierungsbeispielen zu bestätigen. Die Dämpfungsglied-Topologien , T, überbrücktes T und X werden modelliert und hinsichtlich der Phasenbeeinflussung analysiert, sodass eine Bewertung ihrer Eignung durchgeführt werden kann. Weiterhin wird ein innovativer Ansatz zur Linearisierung der Steuerkennlinie vorgestellt und mit Hilfe einer Beispielschaltung mit einem Phasenfehler von 3 ° und einem Steuerlinearitätsfehler von 0,35 dB innerhalb der 1 dB Grenzfrequenz und einem Steuerbereich von 20 dB nachgewiesen. Die Arbeit bietet darüber hinaus eine analytische Betrachtung zu aktiven steuerbaren Verstärkern, welche die besondere Eignung der Gilbert-Zelle aufzeigt und eine geeignete Ansteuerschaltung ableitet. Am Beispiel nach diesem Prinzip entworfener Schaltkreise werden Phasenfehler von nur 0,4 ° innerhalb eines besonders hohen Stellbereichs von 36 dB demonstriert, wodurch eine Vergrößerung des Stellbereichs um den Faktor 4 und eine Verbesserung des Phasenfehlers um den Faktor 2 im Vergleich zum Stand der Technik erreicht wurde. Es wird der Zirkulator-Phasenschieber maßgeblich durch eine neuartige geeignete Ansteuerung verbessert. Damit werden die sonst für die Amplitudenbeeinflussung im Wesentlichen verantwortlichen Varaktoren überflüssig, ohne dabei den schaltungstechnischen Aufwand zu erhöhen. Eine Messung der entsprechenden Schaltung bestätigt dies mit einem Amplitudenfehler von nur 0,9 dB für einen Phasenstellbereich von 360 °, was einer Verringerung des Fehlers um den Faktor 3 im Vergleich zu herkömmlichen Zirkulator-Phasenschiebern entspricht. Abschließend wird der Funktionsnachweis mehrerer entworfener Vektor-Modulatoren mit einer effektiven Genauigkeit von bis zu 6 bit in Einzelschaltungen, Hybridaufbauten und schließlich im Rahmen eines vollständig integrierten Empfängerschaltkreises erbracht. Dieser erzielt eine Verdopplung der Reichweite bei einer um nur 35% höheren Leistungsaufnahme gegenüber einem herkömmlichen Kommunikationsverfahren (SISO). / The present work is dedicated to the investigation and enhancement of amplitude and phase control methods and circuits. The aim is to enhance the performance of these circuits in modern radio frequency transceivers with a comparable or even lower effort and power consumption. A prove of concept will be delivered with implementation examples. By means of models of the passive attenuator topologies , T, bridged-T and X, a thorough analysis is performed in order to compare them regarding their impact on the signal phase. Additionally, a novel approach to increase the control linearity of the attenuators is proposed and verified by measurements, showing a phase error of 3 ° and a control linearity error of 0,35 dB at the 1 dB corner frequency, successfully. The work also presents an investigation on variable gain amplifiers and reveals the superior performance of the Gilbert cell with respect to low phase variations. A cascode biasing circuit that supports these properties is proposed. Measurements prove this concept with relative phase errors of 0,4 ° over a wide attenuation control range of 36 dB thus cutting the error by half in a four times wider control range. The circulator based phase shifting approach is chosen and improved significantly by means of tuning the transconductor instead of the varactors thus removing their impact on signal amplitude. The approach is supported by measurements yielding an amplitude error of only 0,9 dB within a phase control range of 360 ° which corresponds to an improvement by a factor of three compared to recent circulator phase shifters. Finally, the design of several vector modulator topologies is shown with hardware examples of single chips, hybrid printed circuit boards and highly integrated system level ICs demonstrating a full receiver. By using improved variable gain amplifiers, an effective vector modulator resolution of 6 bit without calibration is achieved. Furthermore, a multiple-input multiple-output system is demonstrated that doubles the coverage range of common SISO systems with only 35% of additional power consumption.

abstract: Kinetic inductance springs from the inertia of charged mobile carriers in alternating electric fields and it is fundamentally different from the magnetic inductance which is only a geometry dependent property. The magnetic inductance is proportional to the volume occupied by the electric and magnetic fields and is often limited by the number of turns of the coil. Kinetic inductance on the other hand is inversely proportional to the density of electrons or holes that exert inertia, the unit mass of the charge carriers and the momentum relaxation time of these charge carriers, all of which can be varied merely by modifying the material properties. Highly sensitive and broadband signal amplifiers often broaden the field of study in astrophysics. Quantum-noise limited travelling wave kinetic inductance parametric amplifiers offer a noise figure of around 0.5 K ± 0.3 K as compared to 20 K in HEMT signal amplifiers and can be designed to operate to cover the entire W-band (75 GHz – 115 GHz).The research cumulating to this thesis involves applying and exploiting kinetic inductance properties in designing a W-band orthogonal mode transducer, quadratic gain phase shifter with a gain of ~49 dB over a meter of microstrip transmission line. The phase shifter will help in measuring the maximum amount of phase shift ∆ϕ_max (I) that can be obtained from half a meter transmission line which helps in predicting the gain of a travelling wave parametric amplifier. In another project, a microstrip to slot line transition is designed and optimized to operate at 150 GHz and 220 GHz frequencies, that is used as a part of horn antenna coupled microwave kinetic inductance detector proposed to operate from 138 GHz to 250 GHz. In the final project, kinetic inductance in a 2D electron gas (2DEG) is explored by design, simulation, fabrication and experimentation. A transmission line model of a 2DEG proposed by Burke (1999), is simulated and verified experimentally by fabricating a capacitvely coupled 2DEG mesa structure. Low temperature experiments were done at 77 K and 10 K with photo-doping the 2DEG. A circuit model of a 2DEG coupled co-planar waveguide model is also proposed and simulated. / Dissertation/Thesis / Masters Thesis Electrical Engineering 2016