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Pages
- Title
- CLASS F AND INVERSE CLASS F POWER AMPLIFIER SUBJECT TO ELECTRICAL STRESS EFFECT.
- Creator
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Skaria, Giji, Yuan, Jiann, University of Central Florida
- Abstract / Description
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This study investigated the Class F and inverse Class F RF power amplifier operating at 5.8 GHz. The major challenging issue in design and implementation of CMOS power transistor is the breakdown voltage especially in sub-micron CMOS technologies. In order to eliminate this problem a Cascode topologies were implemented to reduce the Drain-to-Source voltage (stress). A Cascode Class F & Inverse Class F RF power amplifier were designed, and optimized in order to improve efficiency and...
Show moreThis study investigated the Class F and inverse Class F RF power amplifier operating at 5.8 GHz. The major challenging issue in design and implementation of CMOS power transistor is the breakdown voltage especially in sub-micron CMOS technologies. In order to eliminate this problem a Cascode topologies were implemented to reduce the Drain-to-Source voltage (stress). A Cascode Class F & Inverse Class F RF power amplifier were designed, and optimized in order to improve efficiency and reliability using 0.18[micro]m CMOS technology process. A 50% decrease in the stress has been achieved in the Cascode class-F and Inverse class F amplifiers. The sensitivity and temperature effect were investigated using BSIM-4 model. Such an amplifier was designed and optimized for a good sensitivity. A substrate bias circuit was implemented to achieve a good sensitivity. Recommendations were made for future advancements for modification and optimization of the class F and inverse class F circuit by the application of other stress reduction strategies, and improvement of the substrate bias circuit for a better sensitivity.
Show less - Date Issued
- 2011
- Identifier
- CFE0004030, ucf:49161
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004030
- Title
- Automated Hybrid Singularity Superposition and Anchored Grid Pattern BEM Algorithm for the Solution of the Inverse Geometric Problem.
- Creator
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Ni, Marcus, Kassab, Alain, Divo, Eduardo, Chopra, Manoj, University of Central Florida
- Abstract / Description
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A method for solving the inverse geometrical problem is presented by reconstructing the unknown subsurface cavity geometry using boundary element methods, a genetic algorithm, and Nelder-Mead non-linear simplex optimization. The heat conduction problem is solved utilizing the boundary element method, which calculates the difference between the measured temperature at the exposed surface and the computed temperature under the current update of the unknown subsurface flaws and cavities. In a...
Show moreA method for solving the inverse geometrical problem is presented by reconstructing the unknown subsurface cavity geometry using boundary element methods, a genetic algorithm, and Nelder-Mead non-linear simplex optimization. The heat conduction problem is solved utilizing the boundary element method, which calculates the difference between the measured temperature at the exposed surface and the computed temperature under the current update of the unknown subsurface flaws and cavities. In a first step, clusters of singularities are utilized to solve the inverse problem and to identify the location of the centroid(s) of the subsurface cavity(ies)/flaw(s). In a second step, the reconstruction of the estimated cavity(ies)/flaw(s) geometry(ies) is accomplished by utilizing an anchored grid pattern upon which cubic spline knots are restricted to move in the search for unknown geometry. Solution of the inverse problem is achieved using a genetic algorithm accelerated with the Nelder-Mead non-linear simplex. To optimize the cubic spline interpolated geometry, the flux (Neumann) boundary conditions are minimized using a least squares functional. The automated algorithm successfully reconstructs single and multiple subsurface cavities within two dimensional mediums. The solver is also shown to accurately predict cavity geometries with random noise in the boundary condition measurements. Subsurface cavities can be difficult to detect based on their location. By applying different boundary conditions to the same geometry, more information is supplied at the boundary, and the subsurface cavity is easily detected despite its low heat signature effect at the boundaries. Extensions to three-dimensional applications are outlined.
Show less - Date Issued
- 2013
- Identifier
- CFE0004900, ucf:49644
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004900
- Title
- Structure, stability, vibrational, thermodynamic, and catalytic properties of metal nanostructures: size, shape, support, and adsorbate effects.
- Creator
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Behafarid, Farzad, Roldan Cuenya, Beatriz, Chow, Lee, Heinrich, Helge, Kara, Abdelkader, Schoenfeld, Winston, University of Central Florida
- Abstract / Description
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Recent advances in nanoscience and nanotechnology have provided the scientific community with exciting new opportunities to rationally design and fabricate materials at the nanometer scale with drastically different properties as compared to their bulk counterparts. In this dissertation, several challenges have been tackled in aspects related to nanoparticle (NP) synthesis and characterization, allowing us to make homogenous, size- and shape-selected NPs via the use of colloidal chemistry,...
Show moreRecent advances in nanoscience and nanotechnology have provided the scientific community with exciting new opportunities to rationally design and fabricate materials at the nanometer scale with drastically different properties as compared to their bulk counterparts. In this dissertation, several challenges have been tackled in aspects related to nanoparticle (NP) synthesis and characterization, allowing us to make homogenous, size- and shape-selected NPs via the use of colloidal chemistry, and to gain in depth understanding of their distinct physical and chemical properties via the synergistic use of a variety of ex situ, in situ, and operando experimental tools. A variety of phenomena relevant to nanosized materials were investigated, including the role of the NP size and shape in the thermodynamic and electronic properties of NPs, their thermal stability, NP-support interactions, coarsening phenomena, and the evolution of the NP structure and chemical state under different environments and reaction conditions.
Show less - Date Issued
- 2012
- Identifier
- CFE0004779, ucf:49796
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004779
