Engineering Commons^™

A High Gain Multi-Stage Operational Amplifier Using Compound Transconductance Element, Chandra Sekhar Acharyulu Durisety

Doctoral Dissertations

The rapid increase in integrated circuit complexity attributed to the advancements in fabrication techniques combined with the increasing demand for consumer applications has created an immense demand for high performance analog systems. These analog systems include high-resolution (≥ 14-bit) and/or high-speed (≥ 1 GHz) ADCs, high- linearity filters and power management circuits. The fundamental limitations in these systems are tied to the constraints imposed by the basic design elements that tend to include amplifiers and reference generators (voltage/current). With continued technology scaling, innovative circuits and design techniques are necessary in achieving high performance analog/mixed-signal systems.

The goal of this research …

Temperature Dependent Analytical Modeling, Simulation And Characterizations Of Hemts In Gallium Nitride Process, Hasina F. Huq

Doctoral Dissertations

Research is being conducted for a high-performance building block for high frequency and high temperature applications that combine lower costs with improved performance and manufacturability. Researchers have focused their attention on new semiconductor materials for use in device technology to address system improvements. Of the contenders, silicon carbide (SiC), gallium nitride (GaN), and diamond are emerging as the front-runners.

GaN-based electronic devices, AlGaN/GaN heterojunction field effect transistors (HFETs), are the leading candidates for achieving ultra-high frequency and high-power amplifiers. Recent advances in device and amplifier performance support this claim. GaN is comparable to the other prominent material options for high-performance …

Design And Development Of Triangular, Spiral, And Fractal Antennas For Radio Frequency Identification Tags, Jeevan K. Vemagiri

Doctoral Dissertations

This dissertation reports on the design and development of three compact, non-meandered microstrip patch antennas for ultra high frequency (UHF) radio frequency identification (RFID) applications. The monopole antennas considered in this work are an inset-fed triangular antenna, one arm Archimedes spiral antenna and a Half-Sierpinski fractal antenna. These antennas with small length to width ratios (< 2/1), can be the preferred choice, in the tagging of small size consumer end products, over the ubiquitous meandered dipole antenna (length/width > 5/1), which is often the antenna of choice, due to its high gain for UHF RFID applications. The lengths and widths of all three antennas are less than 5.5 cm. Earlier reports of planar antennas for RFID applications in the UHF range have lengths …

Delay Line Based Passive Radio Frequency Identification Tags, Aravind Chamarti

Doctoral Dissertations

This work describes the concept, design, fabrication, and characterization of delay-based radio frequency identification (RFID) tags and RFID-based sensor tags, representing a novel RFID technology. The presented delay-based RFID concept is based on the LC-delay-line and transmission-delay-line based approaches. The proposed concept allows the realization of RFIDs and RFID-based sensor tags at any allowed radio frequency, with the limitation of realizing delay elements capable of producing required delays. The RFID configurations presented in this work are for operation at 915 MHz. Simulations are used to design and optimize components and devices that constitute the tags, and to integrate them to …

A Generalized Instantaneous Nonactive Power Theory For Parallel Nonactive Power Compensation, Yan Xu

Doctoral Dissertations

Although the definitions of active power and nonactive power in a three-phase sinusoidal power system have been accepted as a standard, it has been an issue on how to define instantaneous nonactive power in power systems with non-sinusoidal or even non- periodic voltage and/or current.

This dissertation summarizes these nonactive power theories, and a generalized instantaneous nonactive power theory is presented. By changing the parameters in the instantaneous active current and nonactive current definitions, this theory is valid for power systems with different characteristics. Furthermore, other nonactive power theories can be derived from this generalized theory by changing parameters.

This …

Development And Applications Of Inkjet Printed Conducting Polymer Micro-Rings, Rajneek K. Khillan

Doctoral Dissertations

A drying sessile drop moves the solute particles to the periphery where they get deposited in the form of a ring. This phenomenon is prevalent even with micro drops falling at high velocity from a piezo-actuator based inkjet printer. In polymer microelectronic field, this phenomenon is a major challenge for fabricating devices using inkjet printing. We exploited this problem and applied it for various novel applications in the field of polymer microelectronics.

Various dispensing techniques and temperature variations for micro-drop printing were used for modifying the micro-drops in such a way that the periphery of the micro-ring holds most of …

Nanodot-Based Organic Memory Devices, Zhengchun Liu

Doctoral Dissertations

In this study, resistor-type, diode-type, and transistor-type organic memory devices were investigated, aiming at the low-cost plastic integrated circuit applications. A series of solution-processing techniques including spin-coating, inkjet printing, and self-assembly were employed to fabricate these devices.

The organic resistive memory device is based on a novel molecular complex film composed of tetracyanoquinodimethane (TCNQ) and a soluble methanofullerene derivative [6,6]-phenyl C61-butyric acid methyl ester (PCBM). It has an Al/molecules/Al sandwich structure. The molecular layer was formed by spin-coating technique instead of expensive vacuum deposition method. The current-voltage characteristics show that the device switches from the initial 'low' conduction state to …