Engineering Commons^™

Highly Power Dense Dc To Three-Phase Ac Modular Converters With Tiny Module Capacitors, Wiwin Hartini Lew

Dissertations and Theses

A Modular Multilevel Converter (MMC) is an attractive candidate in high power conversion due to its modularity and scalability. The energy storage element, namely the module capacitance in the MMC submodule circuit, is typically large and when scaled to convert high power, requires very bulky module capacitors. In addition to deteriorating the power density, the design necessitates the use of electrolytic capacitors, which further affects the overall converter efficiency and reliability. This research presents an MMC submodule topology and the accompanying modulation approach that reduces the submodule capacitance requirements significantly compared to conventional MMC topology (few micro-farads versus several milli-farads). …

High-Precision, Mixed-Signal Mismatch Measurement Of Metal-Oxide-Metal Capacitors And A 13-Ghz 5-Bit 360-Degree Phase Shifter, Danilo Bustamante

Theses and Dissertations

A high-precision mixed-signal mismatch measurement technique for metal-oxide metal (MoM) capacitors as well as the design of a 13-GHz 5-bit 360-degree phase shifter are presented. This thesis presents a high-precision, mixed-signal mismatch measurement technique for metal-oxide–metal capacitors. The proposed technique incorporates a switched-capacitor op amp within the measurement circuit to significantly improve the measurement precision while relaxing the resolution requirement on the backend analog-to-digital converter (ADC). The proposed technique is also robust against multiple types of errors. A detailed analysis is presented to quantify the sensitivity improvement of the proposed technique over the conventional one. In addition, this thesis proposes …

Impact Of Calendering And Silver Addition To Carbon Nanotube-Based Electrodes Used In Printed Multi-Layer Capacitors, Ramea Awni Al-Mubarak

Masters Theses

As the demand for global energy increases, the need for development of alternative clean and sustainable energy technology increases. Creating advanced energy devices with a large storage capacity plays a significant role in this development. This research focused on investigating the performance of capacitor devices used as energy storage cells by optimizing and determining the impact of silver percentage and structure (nano-wires or silver flake) added to CNT ink on the conductivity of printed layers, and studying the influence of calendering the multi-layer capacitor electrodes. Multi-layer capacitors were fabricated by screen printing three alternative layers of conductive and dielectric inks …

Self-Supported Printed Multi-Layer Capacitors, Michael James Joyce

Masters Theses

The increasing demand for miniaturized electronic devices has increased the need for rechargeable micro-power sources. Although lithium and lithium ion batteries have been utilized in these applications since the late 1990s, other energy harvesting technologies, such as thermal, mechanical, and solar, are now being used to augment batteries to enable systems to be self-powered. However, the lifetime of any battery is finite, which may be a major problem when the application is in a permanent structure or medical implant device. For power or significant energy storage applications, printed multilayer capacitors or supercapacitors are being explored as an enhancement, or replacement …

Modeling Polarization And Capacitance Hysteresis Of Ferroelectric Capacitors, Bikash Shrestha

Electrical Engineering Theses

A simulation based comparative study of the polarization hysteresis of the ferroelectric capacitor using various ferroelectric models is presented. A 2-dimensional finite element device-level model was implemented using SILVACO's ATLAS device simulator to generate the polarization hysteresis characteristics for Au/Poly(vinylidene fluoride-trifluoroethylene)/Au metal-insulator-metal (MIM) device. Landau free energy expression for electric field in terms of polarization is also implemented in MATLAB to produce the polarization hysteresis curves of monocrystalline and polycrystalline ferroelectrics. The main drawback of previous models was their inability to predict polarization saturation at the same electric field limits as compared with measurements taken from a recently fabricated ferroelectric …

A Mems Multi-Cantilever Variable Capacitor On Metamaterial, Luke A. Rederus

Theses and Dissertations

Negative refractive index materials are an example of metamaterials that are becoming increasingly popular. Research into these metamaterials could possibly be the first steps toward bending electromagnetic radiation (i.e., microwaves, light, etc.) around an object or person. Split ring resonators (SRR) are classified as metamaterials that create an artificial magnetic response from materials with no inherent magnetic properties. Once fabricated, an SRR has a specific resonant frequency due to its permanent geometry. This research introduces a new concept of using a variable capacitive micro- electro-mechanical system (MEMS) device located at the gap of an SRR to mechanically alter the capacitance …

Fabrication, Characterization, And Modeling Of Organic Capacitors, Schottky Diodes, And Field Effect Transistors, Mo Zhu

Doctoral Dissertations

The objectives of this project are to fabricate, characterize, and model organic microelectronic devices by traditional lithography techniques and Technology Computer Aided Design (TCAD).

Organic microelectronics is becoming a promising field due to its number of advantages in low-cost fabrication for large area substrates. There have been growing studies in organic electronics and optoelectronics. In this project, several organic microelectronic devices are studied with the aid of experimentation and numerical modeling.

Organic metal-insulator-metal (MIM) and metal-insulator-semiconductor (MIS) capacitors consisting of insulating polymer poly(4-vinylphenol) (PVP) have been fabricated by spin-coating, photo lithography, and reactive ion etching techniques. Based on the fabricated …

Polymer-Based Capacitors, Junction Field -Effect Transistors, And A Follower Circuit By Lithography, Self -Assembly, And Ink -Jet Printing Techniques, Yuxin Liu

Doctoral Dissertations

The study of organic materials to create field-effect transistors has recently emerged and is gaining much interest. All-polymer electronic devices are currently in their infancy, like semiconductor devices when they first appeared. As a result, current performance of these devices is in no way comparable to the state-of-the-art semiconductor devices. However, all-polymer devices have a few possible appealing advantages. First, all polymer devices have the potential for low-cost fabrication due to their ease of manufacturability, with fewer and simpler processing steps compared with solid-state semiconductor devices. Secondly, polymer devices offer the ability of material flexibility. Lastly, polymer devices may prove …

Simulation Of The Variability In Microelectronic Capacitors Having Polycrystalline Dielectrics With Columnar Microstructure, Jesse Cousins

Electronic Theses and Dissertations

Increasing circuit densities drive the search for microelectronic capacitors with smaller areas. One solution which reduces capacitor size while leaving capacitance constant is to use a thin film of a high permittivity material such as Ta205, SrTiOy (STO), or (Ba,Sr)Ti03 (BST), whose dielectric constants are much higher than those of currently used dielectrics such as Si02 and Si3N1 One drawback of these dielectric films is that they have a polycrystalline microstructure and the permittivity and leakage current density depend on grain size and orientation. It is unknown how microstructure variations will affect the variability and yield of devices incorporating these …

Characterization Of Hfo2 Capacitors, Fan Yang

Electronic Theses and Dissertations

Hafnium oxide (HfOn) is a promising dielectric for future microelectronic applications. Hf02 thin films (10-75nm) were deposited on Pt/Si02/Si substrates by pulsed DC magnetron reactive sputtering. Top electrodes of Pt were formed by e-beam evapo- ration through an aperture mask on the samples to create MIM (Metal-Insulator-Metal) capacitors. Various processing conditions (Arloz ratio, DC power and deposition rate) and post-deposition annealing conditions (time and temperature) were investigated. The structure of the Hf02 films was characterized by X-ray diffraction (XRD) and the roughness was measured by a profilometer. The electrical properties were characterized in terms of their relative permittivity (E,(T) and …

Reliability Studies On Solid Tantalum Electrolytic Capacitors By Means Of Accelerated Life Tests, Venkata R. Golthi

Theses

The purpose of this thesis is to understand the failure mechanisms in Solid Tantalum Capacitors encapsulated in plastic, and to suggest the precautionary measures that prevent the occurrence of these failures.

The reliability of Solid Tantalum Capacitors encapsulated in plastic is of considerable interest because in some applications where the mechanical accelerations or shocks are considerable the "better" "hermitically" sealed type are not able to sustain themselves. Poor adherence between the dielectric film and the base metal Tantalum under the conditions of sudden mechanical shocks, causes problems.

Our study was carried out in two different directions, theoretical and experimental. The …

Reliability Studies On Solid Tantalum Electrolytic Capacitors, Hamed Nassar

Theses

The primary objective of this thesis is to determine and analyze the failure mechanisms of solid tantalum capacitors, pinpoint the causes, and suggest the precautionary measures that prevent the occurrence of these failures. To achieve this goal, the study went in two directions, theoretical and experimental. The theoretical part-is a comprehensive review of the work -done on tantalum capacitors since 1960 up to date.

The experimental part of the study is a life test (1000 hours) of solid tantalum capacitors under humidity and high temperature. To avoid the misconception that could happen by investigating a particular manufacturer's product, units from …