xviii, 213 p. / A print copy of this title is available through the UO Libraries under the call number: SCIENCE QC476.5 .F67 2006 / We investigate models describing two classes of microresonators: those having the shape of a dome, and those having an oval (deformed circle or sphere) shape. We examine the effects of dielectric interfaces in these structures. For the dome cavity, we derive efficient numerical methods for finding exact electromagnetic resonances. In the dome consisting of a concave conductor and a planar, dielectric Bragg mirror, we discover a phenomenon which we call paraxial mode mixing (PMM) or classical spin-orbit coupling. PMM is the sensitive selection of the true electromagnetic modes. The true modes are generally mixtures of pairs of vectorial Laguerre-Gauss modes. While each member of an LG pair possesses definite orbital angular momentum and spin (polarization), the mixed modes do not, and exhibit rich, non-uniform polarization patterns. The mixing is governed by an orthogonal transformation specified by the mixing angle (MA). The differences in reflection phases of a Bragg mirror at electric s and p polarization can be characterized in the paraxial regime by a wavelength-dependent quantity εs - εp. The MA is primarily determined by this quantity and varies with an apparent arctangent dependence, concomitant with an anticrossing of the maximally mixed modes. The MA is zero order in quantities that are small in the paraxial limit, suggesting an effective two-state degenerate perturbation theory. No known effective Hamiltonian and/or electromagnetic perturbation theory exists for this singular, vectorial, mixed boundary problem. We develop a preliminary formulation which partially reproduces the quantitative mixing behavior. Observation of PMM will require both small cavities and highly reflective mirrors. Uses include optical tweezers and classical and quantum information. For oval dielectric resonators, we develop reduced models for describing whispering gallery modes by utilizing sequential tunneling, the Goos-H¨anchen (GH) effect, and the generalized Born-Oppenheimer (adiabatic) approximation (BOA). While the GH effect is found to be incompatible with sequential tunneling, the BOA method is found to be a useful connection between ray optics and the exact wave solution. The GH effect is also shown to nicely explain a new class of stable V-shaped dome cavity modes. / Adviser: Dr. Jens Noeckel.

M.Ing. / 50 Hz technology has led the plasma torch converters up to now. This technology was used. The high power levels of plasma torches made it difficult to implement high frequency technology. At this stage it is possible to use high-frequency technology in plasma torch applications. This thesis implements a high frequency converter suitable for plasma applications. The converter used for this application is the Partial Series Resonant Converter. A study launched to get the properties of plasmas showed that the control method used at this stage namely current control is not the ideal control method. Changing the control method of the converter made it possible to see what influence it has on the plasma. A thorough large signal analisis of the Partial Series Resonant Converter was done. From this analisis a transfer function of the converter was developed and the control parameters were calculated. This control parameters made it possible to change the control and to investigate the different control methods. The design of the plasma torch converter was based on the design of a distributed transformer, input and output filter and a non-linear controller. The results of the Partial Series Resonant Converter showed that power control leads to a more stable plasma. This thesis made a positive contribution to the knowledge of plasma torches and the knowledge of plasma torch converters. The thesis forms a summarry of plasmas and plasma-related topics, and futher study fields are defined by this thesis.

Cheng Sin-hang. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (leaves 90-92). / Abstracts in English and Chinese. / Chapter Chapter 1 --- Introduction --- p.1 / Chapter Chapter 2 --- Theory of Oscillator Design --- p.4 / Chapter 2.1 --- Open-loop approach --- p.4 / Chapter 2.2 --- One-port approach --- p.6 / Chapter 2.3 --- Two-port approach --- p.9 / Chapter 2.4 --- Voltage controlled oscillator (VCO) design --- p.10 / Chapter 2.4.1 --- Active device selection and biasing --- p.11 / Chapter 2.4.2 --- Feedback circuit design --- p.15 / Chapter 2.4.3 --- Frequency tuning circuit --- p.20 / Chapter Chapter 3 --- Noise in Oscillators --- p.23 / Chapter 3.1 --- Origin of phase noise --- p.23 / Chapter 3.2 --- Impact of phase noise in communication system --- p.28 / Chapter 3.3 --- Phase noise consideration in VCO design --- p.30 / Chapter Chapter 4 --- Low Temperature Co-Fired Ceramic --- p.31 / Chapter 4.1 --- LTCC process --- p.31 / Chapter 4.1.1 --- LTCC fabrication process --- p.32 / Chapter 4.1.2 --- LTCC materials --- p.34 / Chapter 4.1.3 --- Advantages of LTCC technology --- p.35 / Chapter 4.2 --- Passive components realization in LTCC --- p.37 / Chapter 4.2.1 --- Capacitor --- p.37 / Chapter 4.2.2 --- Inductor --- p.42 / Chapter Chapter 5 --- High-Q LTCC Resonator Design --- p.47 / Chapter 5.1 --- Definition of Q-factor --- p.47 / Chapter 5.2 --- Stripline --- p.50 / Chapter 5.3 --- Power losses --- p.52 / Chapter 5.4 --- Laminated stripline resonator design --- p.53 / Chapter 5.4.1 --- λ/4 resonator structure --- p.57 / Chapter 5.4.2 --- Meander-line resonator structure --- p.60 / Chapter 5.4.3 --- Bi-metal-layer resonator structure --- p.63 / Chapter Chapter 6 --- LTCC Voltage Controlled Oscillator Design --- p.67 / Chapter 6.1 --- Circuit design --- p.67 / Chapter 6.2 --- Output filter --- p.68 / Chapter 6.3 --- Embedded capacitor --- p.71 / Chapter 6.4 --- VCO layout and simulation --- p.72 / Chapter Chapter 7 --- Experimental Setup and Results --- p.77 / Chapter 7.1 --- Measured Result: LTCC resonators --- p.77 / Chapter 7.1.1 --- Experimental results --- p.79 / Chapter 7.2 --- Measured results: LTCC voltage controlled oscillators --- p.83 / Chapter Chapter 8 --- Conclusion and Future Work --- p.88 / Reference List --- p.90 / Appendix A: TRL calibration method --- p.93 / Appendix B: Q measurement --- p.103 / Appendix C: Q-factor extraction program listing --- p.109 / Chapter 1. --- Function used to calculate Q from s-parameter --- p.109 / Chapter 2. --- Function used to calculate Q from z-parameter --- p.111

The most accurate method for performing analog signal processing in MOS (metal-oxide-semiconductor) integrated circuits is through the use of switched-capacitor circuits. A switched-capacitor circuit operates as a discrete-time signal processor. These circuits have been used in a variety of applications, such as filters, gain stages, voltage-controlled oscillators, and modulators. A switched-capacitor circuit contains operational amplifiers (opamps), capacitators, switches, and a clock generator. Capacitors are used to define the state variables of a system. They store charges for a defined time interval, and determine the state variables as voltage differences. Switches are used to direct the flow of charges and to enable the charging and discharging of capacitors. Nonoverlapping clock signals control the switches and allow charge transfer between the capacitors. Opamps are used in order to perform high-accuracy charge transfer from one capacitor to another. The goal of this research is to design and explore future low-voltage switched-capacitor circuits, which are crucial for portable devices. Low-voltage operation is needed for two reasons: making reliable and accurate systems compatible with the submicron CMOS technology and reducing power consumption of the digital circuits. To this end, three different switched-capacitor integrators are proposed, which function with very low supply voltages. One of these configurations is used to design a lowpass ����� modulator for digital-audio applications. This modulator is fabricated and tested demonstrating 80 dB dynamic range with a 1-V supply voltage. The second part of this research is to show that these low-voltage circuits are suitable for modern wireless communication applications, where the clock and signal frequencies are very high. This part of the research has focused on bandpass analog-to-digital converters. Bandpass analog-to-digital converters are among the key components in wireless communication systems. They are used to digitize the received analog signal at an intermediate center frequency. Such converters are used for digital FM or AM radio applications and for portable communication devices, such as cellular phones. The main block, in these converters, is the resonator, which is tuned to a particular center frequency. A resonator must be designed such that it has a sharp peak at a specific center frequency. However, because of circuit imperfections, the resonant peak gain and/or the center frequency are degraded in existing architectures. Two novel switched-capacitor resonators were invented during the second part of this research. These resonators demonstrate superior performance as compared to previous architectures. A fourth-order low-voltage bandpass ����� modulator, using one of these resonators, has been designed. / Graduation date: 2002

The main topic of this thesis is the performance improvement of microresonators as mass-sensitive biochemical sensors in a liquid environment. Resonant microstructures fabricated on silicon substrates with CMOS-compatible micromachining techniques are mainly investigated. Two particular approaches have been chosen to improve the resolution of resonant chemical/biochemical sensors. The first approach is based on designing a microresonator with high Q-factor in air and in liquid, thus, improving its frequency resolution. The second approach is based on minimizing the frequency drift of microresonators by compensating for temperature-induced frequency variations. A disk-shape resonant microstructure vibrating in a rotational in-plane mode has been designed, fabricated and extensively characterized both in air and in water. The designed resonators have typical resonance frequencies between 300 and 1,000kHz and feature on-chip electrothermal excitation elements and a piezoresistive Wheatstone-bridge for vibration detection. By shearing the surrounding fluid instead of compressing it, damping is reduced and quality factors up to 5800 in air and 94 in water have been achieved. Short-term frequency stabilities obtained from Allan-variance measurements with 1-sec gate time are as low as 1.1 10-8 in air and 2.3 10-6 in water. The performance of the designed resonator as a biological sensor in liquid environment has been demonstrated experimentally using the specific binding of anti-beta-galactosidase antibody to beta-galactosidase enzyme covalently immobilized on the resonator surface. An analytical model of the disk resonator, represented by a simple harmonic oscillator, has been derived and compared with experimental results. The resonance frequency and the Q-factor of the disk resonator are determined from analytical expressions for the rotational spring constant, rotational moment of inertia, and energy loss by viscous damping. The developed analytical models show a good agreement with FEM simulation and experimental results and facilitate the geometrical optimization of the disk-type resonators. Finally, a new strategy to compensate for temperature-induced frequency drifts of resonant microstructures has been developed based on a controlled stiffness modulation by an electronic feedback loop. The developed method is experimentally verified by compensating for temperature-induced frequency fluctuations of a microresonator. In principle, the proposed method is applicable to all resonant microstructures featuring excitation and detection elements.

The objective of the work presented in this thesis is to implement high-Q silicon capacitive micromechanical resonators operating in the HF, VHF and UHF frequency bands. Several variations of a fully silicon-based bulk micromachining fabrication process referred to as HARPSS have been developed, characterized and optimized to overcome most of the challenges facing application of such devices as manufacturable electronic components. Several micromechanical structures for implementation of high performance capacitive silicon resonators covering various frequency ranges have been developed under this work. Design criteria and electromechanical modeling of such devices is presented. Under this work, HF and VHF resonators with quality factors in the tens of thousands and RF-compatible equivalent electrical impedances have been implemented successfully. Resonance frequencies in the GHz range with quality factors of a few thousands and lowest motional impedances reported for capacitive resonators to date have been achieved. Several resonator coupling techniques for implementation of higher order resonant systems with possibility of extension to highly selective bandpass filters have been investigated and practically demonstrated. Finally, a wafer-level vacuum sealing technique applicable to such resonators has been developed and its reliability and hermeticity is characterized.