Graduation date: 2006 / The design of a 10-bit pipelined charge redistribution DAC employing MOSCAPs biased in their accumulation mode is presented in this thesis. A switched capacitor filter and output buffer have also been designed for the system. The effect of MOSCAP nonlinearity on the performance of the pipelined charge redistribution DAC has been analyzed. MOS capacitors and their models available for simulation have been discussed. In addition, the effect of more general capacitor nonlinearities on the performance of the DAC has been presented.

Design of filters used in grid-connected inverter applications involves multiple constraints. The filter requirements are driven by tight filtering tolerances of standards such as IEEE 519-1992–IEEE Recommended Practices and Requirements for Harmonic Control in Electrical Power Systems and IEEE 1547.2-2008–IEEE Application Guide for IEEE Std 1547, IEEE Standard for Interconnecting Distributed Resources with Electric Power Systems. Higher order LCL filters are essential to achieve these regulatory standard requirements at compact size and weight. This objective of this thesis report is to evaluate design procedures for such higher order LCL filters. The initial configuration of the third order LCL filter is decided by the frequency response of the filter. The design equations are developed in per-unit basis so results can be generalized for different applications and power levels. The frequency response is decided by IEEE specifications for high frequency current ripple at the point of common coupling. The appropriate values of L and C are then designed and constructed. Power loss in individual filter components is modeled by analytical equations and an iterative process is used to arrive at the most efficient design. Different combinations of magnetic materials (ferrite, amorphous, powder) and winding types (round wire, foil) are designed and tested to determine the most efficient design. The harmonic spectrum, power loss and temperature rise in individual filter components is predicted analytically and verified by actual tests using a 3 phase 10 kW grid connected converter setup. Experimental results of filtering characteristics show a good match with analysis in the frequency range of interconnected inverter applications. The design process is stream-lined for the above specified core and winding types. The output harmonic current spectrum is sampled and it is established that the harmonics are within the IEEE recommended limits. The analytical equations predicting the power loss and temperature rise are verified by experimental results. Based on the findings, new LCL filter combinations are formulated by varying the net Lpu to achieve the highest efficiency while still meeting the recommended IEEE specifications. Thus a design procedure which can enable an engineer to design the most efficient and compact filter that can also meet the recommended guidelines of harmonic filtering for grid-connected converter applications is established.

University of Macau / Faculty of Science and Technology / Department of Electrical and Computer Engineering

A new class of micromachined devices called thin-film piezoelectric-on-substrate (TPoS) resonators is introduced, and the performance of these devices in RF and sensor applications is studied. TPoS resonators benefit from high electromechanical coupling of piezoelectric transduction mechanism and superior acoustic properties of a substrate such as single crystal silicon. Therefore, the motional impedance of these resonators are significantly smaller compared to typical capacitively-transduced counterparts while they exhibit relatively high quality factor and power handling and can be operated in air. The combination of all these features suggests TPoS resonators as a viable alternative for current acoustic devices. In this thesis, design and fabrication methods to realize dispersed-frequency lateral-extensional TPoS resonators are discussed. TPoS devices are fabricated on both silicon-on-insulator and thin-film nanocrystalline diamond substrates. The performance of these resonators in simple and low-power oscillators is measured and compared. Furthermore, a unique coupling technique for implementation of high frequency filters is introduced in which dual resonance modes of a single resonant structure are coupled. The measured results of this work show that these filters are suitable candidates for single-chip implementation of multiple-frequency narrow-band filters with high out-of-band rejection in a small footprint.

This dissertation reports, for the first time, on the design and implementation of tunable micromachined bandpass filters in the ultra high frequency (UHF) range that are fully integrated on CMOS-grade (resistivity=10-20 ohm.cm) silicon. Filters, which are designed in the Elliptic and coupled-resonator configuration, are electrostatically tuned using tunable microelectromechanical (MEM) capacitors with laterally movable interdigitated fingers. Tunable filters and high-quality factor (Q) integrated passives are made in silver (Ag), which has the highest conductivity of all materials in nature, to reduce the ohmic loss. The loss of the silicon substrate is eliminated by using micromachining techniques. The combination of the highest-conductivity metal and a low-loss substrate significantly improves the performance of lumped components at radio frequencies (RF), resulting in an insertion loss of 6 dB for a tunable lumped bandpass filter at 1075 MHz with a 3 dB-bandwidth of 63 MHz and tuning range of 123 MHz. The bandpass filters are encapsulated at the wafer level using a low-temperature, thermally released, polymer packaging process. This thesis details the design, fabrication, and measurement results of the filters and provides strategies to improve their performance. The performance of filter components, including the tunable capacitors and inductors, is characterized and compared to the state-of-the-art micromachined passive components. The silver inductors reported in this thesis exhibit the record high Q, and the silver bandpass filters show the minimum insertion loss that has been achieved on a CMOS-grade silicon substrate, to the best of our knowledge. Alternatively, tunable capacitors can be made in the bulk of silicon using a modified version of the high-aspect-ratio polysilicon and single crystal silicon (HARPSS) fabrication technique to obtain a larger capacitance density at the expense of a higher conductive loss. Using this process, a 15 pF two-port tunable capacitor is fabricated and tuned by 240% with the application of 3.5 V to the isolated actuator. Silver inductors can be post integrated with HARPSS tunable capacitors to obtain tunable filters in the very high frequency (VHF) range. The reported bandpass filters can be monolithically integrated with CMOS and have the potential to replace several transmit and receive acoustic filters currently used in cellular phones.

Thesis (M.S.)--State University of New York at Binghamton, Department of Systems Science and Industrial Engineering, 2005. / Includes bibliographical references (p. 94-96).

Thesis (M.S.)--State University of New York at Binghamton, Thomas J. Watson School of Engineering and Applied Science, Department of Systems Science and Industrial Engineering, 2007. / Includes bibliographical references.

Thèse (M.Eng.) -- Université du Québec à Chicoutimi, 2007. / La p. de t. porte en outre: Mémoire présenté comme exigence partielle de la maîtrise en ingénierie. CaQCU Bibliogr.: f. [121]-124. Document électronique également accessible en format PDF. CaQCU

Thesis (Ph. D.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2006. / John Papapolymerou, Committee Chair ; Joy Laskar, Committee Member ; John Cressler, Committee Member ; Alan Doolittle, Committee Member ; Clifford Henderson, Committee Member.

Este trabalho apresenta o estudo, projeto e implementação de quatro estratégias de controle de corrente de compensação para uma topologia monofásica de Filtro Ativo de Potência Paralelo (FAPP), sendo estas denominadas, controlador PI Clássico no eixo de coordenadas ( ), controlador PI Clássico no eixo de coordenadas ( – ), Controlador PI Ressonante no eixo de coordenadas ( ) e Controlador PI Ressonante no eixo de coordenadas ( ). A tensão no barramento CC é controlada por um controlador PI clássico. O FAPP é composto por um inversor full-bridge conectado a rede elétrica, o qual opera de modo a fornecer à rede elétrica uma corrente de compensação, com a mesma amplitude e em fase oposta à corrente harmônica da carga. O algoritmo baseado no sistema de eixos de referência síncrona (algoritmo ) é utilizado para obtenção da corrente de referência de compensação. Análises matemáticas são realizadas de forma a obter o modelo que representa o sistema físico do FAPP. Além disso, é apresentada uma metodologia de projeto para a obtenção dos ganhos dos controladores PI das malhas de corrente e de tensão do barramento CC. É também apresentada à metodologia para sintonia das parcelas ressoantes dos controlador e . Resultados de simulação e experimentais são apresentados de forma a validar o desenvolvimento teórico realizado e comparar o desempenho do FAPP, quando submetido às estratégias de controle propostas. / This work presents the study, design and implementation of three control strategies for compensating current in a single-phase Shunt Active Power Filter (SAPF), such as the conventional PI controller based on reference frame ( ), conventional PI controller based on reference frame ( ), PI plus resonant controller based on reference frame ( ) and PI plus resonant controller based on reference frame ( ). The DC bus voltage is controlled by using a linear PI controller. The SAPF consists of a full-bridge inverter connected to the grid. The main function of the shunt SAPF is to provide to the utility grid an adequate compensation current, containing the same amplitude and opposite phase of the load current harmonics. The algorithm used for obtaining the reference compensation current is based on the synchronous reference frame (SRF algorithm). Mathematical analyzes are developed in order to obtain the mathematical model which represents the SAPF physical system. In addition, it is presented a design methodology employed for obtaining the gains of the PI controllers used in both the compensation current and the DC-bus voltage loops. It is also presented methodology for tuning the resonant controllers. Simulation and experimental results are presented to validate the theoretical development and compare the performance of FAPP when submitted to the proposed control strategies.