Engineering Commons^™

Analysis And Comparison Of Popular Models For Current-Mode Control Of Switch Mode Power Supplies, Ramchandra M. Kotecha

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Current-mode control is the most popular scheme used for the operation of SMPS (Switch Mode Power Supplies). Current-mode control, also known as current-programmed mode or current-injected control is a multi-loop control scheme that has an inner loop and an outer voltage loop. The current loop controls the inductor peak current while the voltage loop controls the output voltage. The inner loop follows a set program by the outer loop. Some of the most popular small-signal models that predict the small-signal characteristics of current-mode control scheme have been analyzed and compared in this thesis. A PWM dc-dc buck converter in CCM(Continuous …

Performance Analysis Of Radar Waveforms For Congested Spectrums, Shaun W. Frost

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With more users populating the RF spectrum and hence less available contiguous bandwidth, radar and communication waveforms are slowly forced to become more efficient at using their available frequencies. Two scenarios are considered: operation in a colored interference environment and operation in discontiguous spectral bands. Unconstrained algorithms for designing transmit waveforms and receive filters are evaluated, wherein varying a convex weight trades performance between spectral flatness and side lobe levels. An empirical study provides performance bounds for constrained radar waveform designs for an instantiation of the interference spectrum.

Closed-form predictions for integrated sidelobe ratio (ISLR) and peak-to-sidelobe ratio (PSLR) for …

Distributed Fault Detection For A Class Of Large-Scale Nonlinear Uncertain Systems, Qi Zhang

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In the distributed large-scale system, the behavior of any subsystem is not only influenced by variables belonging to it (local variables), but also by the variables in other subsystems during its interaction with neighboring subsystems. The effect of the fault in one subsystem will be quickly propagated to other subsystems due to their interconnections. Currently, most of the fault detection and diagnosis schemes are focused on centralized system which do not consider the interaction terms and can not efficiently detect the faults.

In this thesis, a distributed fault detection scheme is developed for a class of large-scale nonlinear uncertain systems …

Small-Signal Modeling Of Resonant Converters, Agasthya Ayachit

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Resonant DC-DC converters play an important role in applications that operate at high-frequencies (HF). Their advantages over those of pulse-width modulated (PWM) DC-DC converters have led to the invention of several topologies over the traditional forms of these converters. Series resonant converter is the subject of study in this thesis. By variation in the switching frequency of the transistor switches, the optimum operating points can be achieved. Hence, the steady-state frequency-domain analysis of the series resonant converter is performed. The operational and characteristic differences between the series resonant and parallel resonant and series-parallel resonant configurations are highlighted. In order to …

Circuit Techniques On Improving Timing And Noise In Dynamic Cmos, Arvind Vaidyanadeswaran

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Dynamic CMOS are widely employed in high-performance CMOS chips due to high speed and less area in comparison with Static CMOS. However, Dynamic CMOS circuits are inherently less noise tolerant than Static CMOS circuits. This problem becomes more severe with aggressive technology scaling into nanometer process, particularly caused by the charge sharing, the sub-threshold leakage current, the power rail noise and the crosstalk noise. In this thesis, circuit techniques on improving both timing and noise of Dynamic CMOS are presented. A comparison with previous reported work is also presented. Simulations proved that the proposed circuit techniques can achieve a high …

Direct Digital Frequency Synthesizer Architecture For Wireless Communication In 90 Nm Cmos Technology, Tri Trong Nguyen

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Software radio is one promising field that can meet the demands for low cost, low power, and high speed electronic devices for wireless communication. At the heart of software radio is a programmable oscillator called a Direct Digital Synthesizer (DDS). DDS has the capabilities of rapid frequency hopping by digital software control while operating at very high frequencies and having sub-hertz resolution. Nevertheless, the digital-to-analog converter (DAC) and the read-only-memory (ROM) look-up table, building blocks of the DDS, prevent the DDS to be used in wireless communication because they introduce errors and noises to the DDS and their performances deteriorate …

Real-Time Fault Diagnosis Of Automotive Electrical Power Generation And Storage System, Luis Farfan-Ramos

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Automobiles depend more and more on electric power. Analysis of warranty data by automotive OEMs shows that faults in the automotive electrical power generation and storage (EPGS) system are often misdiagnosed. Therefore, monitoring of the state of health (SOH) of the automotive EPGS system is vital for early and correct diagnosis of faults in it, ensuring a reliable supply of electric power to the vehicle and reducing maintenance costs. In this research project, a model-based SOH monitoring method for the EPGS system is developed without the requirement of an alternator current sensor. A model representing the dynamic relationship between the …

Design Of A Low Power And Area Efficient Digital Down Converter And Sinc Filter In Cmos 90-Nm Technology, Steven John Billman

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A digital down converter (DDC) typically receives a digital input that has been generated by an analog to digital converter (ADC) operating at intermediate frequency (IF) in an RF receiver chain. The function of the DDC is to down convert the IF signal to baseband in phase (I) and quadrature (Q) signals and is a very important component in wireless receivers. A Digital Down Converter (DDC) is developed based on square wave local oscillators facilitating a multiplier-less implementation with no constraints on the sampling frequency. The DDC includes a pseudo multi-rate SINC low pass filter which exhibits better performance compared …

Self-Calibrating Cricket Motes For Indoor Navigation, Yogendra Jayant Patil

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Global Positioning System (GPS) plays a vital role for providing localization to the autonomous robots. But the quality of the GPS signal degrades in an indoor location and hence GPS cannot be used for indoor localization. Cricket motes are location-aware system that can provide localization service to its users in an indoor location. Cricket motes apply the acoustic ranging technique to find distance between two points. But before a user can use this localization system, assigning coordinate system to the motes requires manual assistance. This project presents a novel algorithm for self-calibration of the cricket motes to a coordinate system …

Structured Silicon Macropore As Anode In Lithium Ion Batteries, Xida Sun

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Porous silicon (PS) membranes for lithium-ion batteries (LIBs) anode applications were developed, demonstrated and characterized systematically in this work. Electrochemical measurements were conducted on both Si-wafer supported and free-standing porous Si membranes. It turned out that the specific capacity of LIBs was enhanced remarkably by PS based anode. PS was fabricated by using electrochemical anodization in a mixed solution of Dimethylformamide (DMF) and Hydrofluoric acid (HF wt.49%). By varying the anodization conditions, including HF concentration, anodization etching time and current density, pores were formed in a p-type (1-20Ω cm) boron-doped silicon substrate. Scanning electron microscopy (SEM) was employed to investigate …

Graphene Based Rf/Microwave Impedance Sensing And Low Loss Conductor For Rf Applications, Iramnaaz Iramnaaz

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Biosensors are becoming more popular recently and expanding due to their broad applications in detecting disease and infectious agents, monitoring of environmental toxins, etc. Recognition and quantification of biochemical molecules and molecular interactions present great challenges in biosensing [38]. Impedance sensing at radio frequency (RF) /microwave frequency becomes very attractive as bio-molecules exhibits large distinct dielectric properties, and also because the ionic conductivity of water in most physiological systems is greatly diminished. For example, it has been reported that tumoral cells exhibits large value of electrical conductivity and permittivity which can result in significant variation of the impedance when compared …

Frequency Diverse Array Receiver Architectures, Aaron M. Jones

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Typical radar systems are limited to energy distribution characteristics that are range independent. However, operators are generally interested in obtaining information at particular ranges and discarding elsewhere. It seems appropriate then to attempt to put energy solely at the range(s) of interest, thus minimizing exposure to clutter, jammers and other range-dependent interferences sources. The frequency diverse array (FDA) can provide a mechanism to achieve range-dependent beamforming and the spatial energy distribution properties are investigated on transmit and receive for different architectures herein.

While simplified FDA receive architectures have been explored, they exclude the return signals from transmitters that are not …

Dynamic Footed With Clock Overlapping And Load Balancing In Multiple Paths For Noise Tolerance In Dynamic Cmos Circuits, Ramadan U. Buzakuk

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Dynamic CMOS circuits are used in microprocessors as well as in circuits that require high speed and small areas. Dynamic CMOS circuits have many advantages but are not robust in noise tolerance in comparison with the legacy static CMOS circuits. In this thesis several noise tolerance techniques that can be implemented with Dynamic CMOS circuits for robust noise tolerance are studied. A dynamic footed with clock overlapping technique integrated with a load balancing multiple-path transistor sizing algorithm for optimizing performance of noise tolerance and speed while in consideration of process variations is presented. Using the 2-bit weighted binary-to-thermometric converter implemented …

Dc-Dc Power Converter Design For A Portable Affordable Welder System (Paws), Curt Stephen Zackiewicz

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Arc welding machines are typically large, heavy devices that transform an alternating current (AC) input into a low-voltage, direct current (DC) output. Traditionally these high power devices have required steel and copper transformers that account for their bulky size and weight. While the cost of raw materials in electromagnetic components has been increasing the cost of high-power silicon devices has been decreasing. This disparity creates an opportunity for a cost-effective DC-DC switching welder in the consumer market. While DC-DC power electronics are not new to the welding industry, this study, under the commission of a welding equipment manufacturer, aims to …

Analysis And Design Of Pulse-Width Modulated Two-Switch Forward Dc-Dc Converter For Universal Laptop Adapter, Venkata Sai Aditya Kumar Choragudi

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The objective of this research is to analyze, design and simulate a two-switch forward pulse-width modulated (PWM) DC-DC converter. The Forward PWM DC-DC converter is originally derived from the buck converter by the addition of a transformer. The transformer is mainly used as a safety feature to electrically isolate input and output stages of the power converter and also to scale the voltage or current. The steady-state analysis is presented for the two-switch PWM DC-DC forward converter in continuous conduction mode (CCM). Based on the analysis, the design equations for two-switch PWM forward DC-DC converter are derived. A design example …

Observer-Based Fault Diagnosis Of Wind Turbines, Songling Zhao

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Because wind is a clean and renewable energy, it is in high demand as an alternative resource of fossil fuels for our daily power supply. Thus, wind turbine technology is wildly applied to convert the wind energy to electrical power. With the size of the wind turbines increased, the maintenance cost of the wind turbines also goes up. Fault diagnosis can significantly help wind turbines to: reduce the maintenance cost, the machinery breakdown, spare parts inventories, total machine downtime, and overtime expenses, and increase machine life, overall productivity, and profit. The technical challenges for fault diagnosis of the wind turbine …

High-Frequency Wide-Range All Digital Phase Locked Loop In 90nm Cmos, Prashanth Muppala

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This thesis presents a high-frequency wide tuning range all digital phase locked loop (ADPLL) in 90 nm CMOS process with 1.2 V power supply. It operates in the frequency range of 2-7.2 GHz with wide linearity and high resolution. The ADPLL uses a wide frequency range digital controlled oscillator (DCO) and averaging technique to obtain fast lock time. The operation of the ADPLL includes both a frequency acquisition state and a phase acquisition state. A novel architecture is implemented in a coarse stage to obtain a monotonically increasing wide frequency range DCO for frequency acquisition and a fine control stage …

Characterization Of Room Temperature Terahertz Direct Detectors, Carla Renee Boggs

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Room temperature direct detectors operating in the so-called Terahertz (THz) region of the electromagnetic spectrum, and representing the most common detection technologies currently available, were characterized at 104, 280 GHz or 600 GHz within their intended range of operating frequencies. These detectors included commercial Schottky-diode rectifiers (Virginia Diodes and Spacek Labs), commercial pyroelectric detectors (Spectrum Detector), and a commercial Golay cell (QMCI). The characterization included antenna patterns, responsivity, electrical noise, noise equivalent temperature difference (NEΔT ), and noise equivalent power (NEP). Since all the characterization measurements were made the same way, quantitative comparisons can be made between the performances of …