Examensarbeten för masterexamen // Master Theses
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- PostPLL Design at 5.8 GHz(2003) Banik, Biddut; Chalmers tekniska högskola / Institutionen för mikroteknologi och nanovetenskap; Chalmers University of Technology / Department of Microtechnology and NanosciencePLL (Phase Locked Loop) with low phase noise is a prerequisite for a communication system. Besides serving the general purposes as in cell phones, PLL is used in the ISM Bands for other special purposes incorporated with other devices. A double-PLL, generates two signals, at the ISM Band 5.8 GHz can be used for many purposes. ETC (Electronic Toll Collection), Traffic Control, thickness measurement are some examples that use ISM bands. The project s aim is to investigate and design a Double PLL at 5.8 GHz which can be used as a part of the system that would measure the thickness of slag in an Iron furnace. Further investigation and design should take place as per necessity. The components used, should hold pronounced commercial perspectives and availability. Based on the investigation results, proper components were selected to design a Single PLL at 5.8 GHz which was followed by a Double PLL at 5.8 GHz. Further investigations were conducted to attain information about commercially available VCOs, followed by a feasibility study of the commercial perspectives. Detailed considerations regarding VCOs led to the way to design VCOs at 5.8 GHz and 9.9 GHz.
- PostInvestigations of Josephson junction parameters for Rapid Single(2003) Engseth, Henrik; Chalmers tekniska högskola / Institutionen för mikroteknologi och nanovetenskap; Chalmers University of Technology / Department of Microtechnology and NanoscienceAbstract This diploma work is about Rapid Single Flux Quantum (RSFQ) circuits. This supercoducting digital circuitry has the most promising properties in terms of speed and power consumption. The active elements of the RSFQ circuits are Josephson junctions (JJ). For their fabrication low temperature superconducting niobium films are used. Today the design and fabrication of RSFQ circuits are done in a standardized way with well-defined design rules. Nevertheless, to design complicated circuits with more than several hundred junctions a lot of practical problems must be solved. Different aspects of the RSFQ circuits design process were investigated in this work. In the theoretical part we propose a new, more realistic model of the Josephson junction for physical simulation (which is necessarily used for design of every RSFQ gate) in order to improve its quality and precision. The new model for the JJ includes additional inductances, which must reflect a specific environment of the junction layout. The influence of parameter deviations was investigated in the simulation. As sources of the deviation we chose the spread of c (the Stewart-McCumber parameter) and that of the inductances. Then the operational margins of the basic elements of the RSFQ logic SR flip-flop were determined and compared with the prediction of the previously used model. To prove the results of simulations we designed a test structure of the SR flip-flop, with c=1 and c=2 for the wellestablished HYPRES technology (USA). Another part of the work is practical measurements. A test chip, containing chains of 100 Josephson junctions was designed and measured in order to estimate the spread of critical currents in real technology.
- PostError analysis of a fiber optic polarimeter(2004) Jellbin, Anders K.; Chalmers tekniska högskola / Institutionen för mikroteknologi och nanovetenskap; Chalmers University of Technology / Department of Microtechnology and Nanoscience
- PostThe analogue mode of surface-stabilised ferroelectric liquid crystals(2004) Hammarquist, Anders; Chalmers tekniska högskola / Institutionen för mikroteknologi och nanovetenskap; Chalmers University of Technology / Department of Microtechnology and Nanoscience
- PostStudy of antenna structures with small dimensions at 5.8 GHz ISM Band(2004) Rafique, Raihan; Chalmers tekniska högskola / Institutionen för mikroteknologi och nanovetenskap; Chalmers University of Technology / Department of Microtechnology and NanoscienceIn recent days, the microstrip antenna is getting more and more attention because of its small dimension, negligible weight, ease of fabrication and option to integrate with active circuits and most of all low cost to produce. The other features those the microstrip antennas offer are ease of fabrication upon the circuit board, can be made with dimension smaller than half wavelength and wide bandwidth can be found. That is why nowadays for any industry related to antenna designing and development feels interested with microstrip antenna for its products. Most components or systems need the microstrip antenna to work for a small range (10meter -1000meter). Wider beamwidth is desirable for such a small range of operation. Here in this thesis, studies are made upon aperture coupled circularly polarized microstrip antenna. Here antenna parameters and radiation pattern are studied to find out the relationship in between them. The study is done on antenna parameters such as excitation of antenna, groundplane size and shape, patch size and shape, and influence of parasitic; based on previous studied and measuring the radiation patterns with different antenna parameters. Simulations are also done to predict the radiation pattern. Several solutions are found to get wider beamwidth and better performance of microstrip antennas. The corner truncated antenna is found the most attractive solution to get wider beamwidth, because it is easy to design and very little modification is needed while implementing this in an ordinary patch antenna.
- PostLong wavelenght VCSELs for gas concentration measurements(2004) Sohtell, Kristoffer M; Chalmers tekniska högskola / Institutionen för mikroteknologi och nanovetenskap; Chalmers University of Technology / Department of Microtechnology and Nanoscience
- PostNumerical Modeling of MSM Photo Detectors(2004) Alsterberg, Maria I H; Chalmers tekniska högskola / Institutionen för mikroteknologi och nanovetenskap; Chalmers University of Technology / Department of Microtechnology and Nanoscience
- PostImaging Systems Using Diffractive Optics(2004) Johansson, Mattias E.B.; Chalmers tekniska högskola / Institutionen för mikroteknologi och nanovetenskap; Chalmers University of Technology / Department of Microtechnology and Nanoscience
- PostLight-sensitive liquid crystals-Characterization(2004) Josefsson, Tom; Chalmers tekniska högskola / Institutionen för mikroteknologi och nanovetenskap; Chalmers University of Technology / Department of Microtechnology and NanoscienceCharacterization of the optical properties for light-sensitive azobenzene nematic liquid crystal under the influense of ultraviolet radiation
- PostSystematic Analysis of Liquid Crystal Alignment Layers(2004) Chen, Xinming; Chalmers tekniska högskola / Institutionen för mikroteknologi och nanovetenskap; Chalmers University of Technology / Department of Microtechnology and Nanoscience
- PostNd:YAG lasers with a high quality beam, using an unstable cavity and an output mirror with a tailored Gaussian/super-Gaussian reflectivity profile(2004) Gustafsson, Per-Erik G; Chalmers tekniska högskola / Institutionen för mikroteknologi och nanovetenskap; Chalmers University of Technology / Department of Microtechnology and Nanoscience
- PostLow-order aberration correction with a membrane deformable mirror for adaptive optics(2004) Eriksson, Emma; Chalmers tekniska högskola / Institutionen för mikroteknologi och nanovetenskap; Chalmers University of Technology / Department of Microtechnology and Nanoscience
- PostPolymer Stabilisation of Chiral Smectic Liquid Crystals for Analogue Electrooptic Applications(2005) Elfström, David; Chalmers tekniska högskola / Institutionen för mikroteknologi och nanovetenskap; Chalmers University of Technology / Department of Microtechnology and Nanoscience
- PostMolecular Electronics - A wide perspective on Nanocell like logic circuits(2005) Önnheim, Carl; Chalmers tekniska högskola / Institutionen för mikroteknologi och nanovetenskap; Chalmers University of Technology / Department of Microtechnology and Nanoscience
- PostManufacturing and Characterization of Nematic Liquid Crystal Cells with Close to Homeotropic Director Orientation(2005) Nnoaham, Ikechukwu; Chalmers tekniska högskola / Institutionen för mikroteknologi och nanovetenskap; Chalmers University of Technology / Department of Microtechnology and Nanoscience
- PostCharacterizations of GaAs-based long wavelenght laser materials by X-ray diffraction(2005) Gu, Qin Fen; Chalmers tekniska högskola / Institutionen för mikroteknologi och nanovetenskap; Chalmers University of Technology / Department of Microtechnology and Nanoscience
- PostMeasurements of internal temperature and thermal impedance of VCSELs(2005) Althoff, Åsa; Chalmers tekniska högskola / Institutionen för mikroteknologi och nanovetenskap; Chalmers University of Technology / Department of Microtechnology and Nanoscience
- PostReading out a qubit through an harmonic oscillator, Simulating the driven Jaynes-Cummings Hamiltonian with dissipation(2005) Tornberg, Lars; Chalmers tekniska högskola / Institutionen för mikroteknologi och nanovetenskap; Chalmers University of Technology / Department of Microtechnology and NanoscienceIn this thesis we investigate the properties of a circuit proposed for reading out the state of a superconducting Cooper-pair box (SCB). The circuit consists of an LC-circuit capacatively coupled to the SCB. By probing the LC-circuit the state of the qubit can be determined. The Hamiltonian for the circuit is derived and found to be the well-known Jaynes-Cummings Hamiltonian. Using the properties of this we can understand why the proposal in question is a good candidate for doing a quantum non-demolition measurement. To model and understand the read-out process we have simulated the open system, including the enviroment. The susceptibility of the circuit is calculated. In an actual experimental situation, microwaves are used to probe the oscillator. Here we model these as quantum mechanical coherent states. Properties of coherent states are then used to device a simple model for calculating the measurement-time. To understand and model the decoherence induced by the measurement we have made numerical simulations of the driven system. These can be used to study the mixing and dephasing of the qubit as function of time and temperature.
- PostDesign and evaluation of phase-deviation sensitive DOEs with possible application in SLM characterization(2005) Milewski, Gabriel; Chalmers tekniska högskola / Institutionen för mikroteknologi och nanovetenskap; Chalmers University of Technology / Department of Microtechnology and NanoscienceThe spatial light modulator (SLM) is a component which permits dynamic phase and/or amplitude shaping of the cross section of a light beam. Thanks to a high efficiency, its wide range of applications includes e.g. optical beam steering and applications in signal processing. This Master thesis presents a method for designing pixelated diffractive optical elements (DOEs) producing spots whose intensities are optimized to heavily depend on a particular phase modulation level. A theoretical expression for the sensitivity is derived and both simulations as well as experiments show that the achieved sensitivities are several times higher than when using conventional, intensity-maximizing, DOE design methods. Eventually, a non-interferometric way of determining the phase modulation characteristics of an 8-bit SLM unit using these DOEs is suggested. The results in one case show an agreement within 20◦ with measurements made by interferometry. As the method is subjected to a different setting of the SLM unit yielding a higher residual amplitude modulation, interferometry and phase retrieval using DOEs agree to a lesser extent.
- PostLiquid crystal filled photonic crystal fibers: Alignment in cylindrical geometry and dielectric properties(2005) Anawati, Anawati; Chalmers tekniska högskola / Institutionen för mikroteknologi och nanovetenskap; Chalmers University of Technology / Department of Microtechnology and Nanoscience