Engineering Commons^™

Identifying An Emi Source And Coupling Path In A Computer System With Sub-Module Testing, S. Radu, Yun Ji, Joe Nuebel, James L. Drewniak, Thomas Van Doren, Todd H. Hubing

Electrical and Computer Engineering Faculty Research & Creative Works

EMI in a workstation server resulting from CPU clock harmonics was investigated. Mechanisms by which noise is coupled off the CPU PCB module were diagnosed from studies and measurements on the CPU PCB alone. A model was then developed. Modifications were made and tested in the fully functional system to support the model.

An Expert System For Predicting Radiated Emi From Pcb's, Navin Kashyap, Todd H. Hubing, James L. Drewniak, Thomas Van Doren

Electrical and Computer Engineering Faculty Research & Creative Works

This paper describes an expert systems approach, based on symbolic reasoning techniques, to the problem of predicting radiated EMI levels from printed circuit boards. The expert system, currently under development at the University of Missouri-Rolla, USA, starts by extracting board geometry information from the board layout files. This information is fed into the classification algorithm, which determines the signal properties and nature of each net, using the knowledge stored in the knowledge base. The evaluation algorithm uses the available in formation to identify and evaluate critical circuit geometries, and then estimates the effect that these geometries have on system radiation …

Effects Of Gapped Groundplanes And Guard Traces On Radiated Emi, D. S. Britt, David M. Hockanson, Fei Sha, James L. Drewniak, Todd H. Hubing, Thomas Van Doren

Electrical and Computer Engineering Faculty Research & Creative Works

Designers sometimes employ gapped reference planes to isolate analog and digital signals, and separate "quiet" and "noisy" ground structures by providing a series impedance. Guard traces are also used to reduce unwanted coupling to adjacent traces, which can lead to signal integrity or EMI problems. This study investigates the impact of gaps and guard traces on radiated EMI. A simple microstrip circuit was constructed to experimentally analyze the effects of groundplane gaps and guard traces.

Lumped-Element Sections For Modeling Coupling Between High-Speed Digital And I/O Lines, Wei Cui, Hao Shi, Xiao Luo, Fei Sha, James L. Drewniak, Thomas Van Doren, T. Anderson

Electrical and Computer Engineering Faculty Research & Creative Works

Lumped-element sections are used for modeling coupling between high-speed digital and I/O lines on printed circuit boards (PCBs) in this paper. Radiated electromagnetic interference (EMI) is investigated when the I/O line going off the board is driven as an unintentional, but effective antenna. Simulated results are compared with measurements for coupled lines. A suitable number of lumped-element sections for modeling is chosen based on the line length and the highest frequency of interest.

Numerical And Experimental Corroboration Of An Fdtd Thin-Slot Model For Slots Near Corners Of Shielding Enclosures, Min Li, Kuang-Ping Ma, David M. Hockanson, James L. Drewniak, Todd H. Hubing, Thomas Van Doren

Electrical and Computer Engineering Faculty Research & Creative Works

Simple design maxims to restrict slot dimensions in enclosure designs below a half-wave length are not always adequate for minimizing electromagnetic interference (EMI). Complex interactions between cavity modes, sources, and slots can result in appreciable radiation through nonresonant length slots. The finite-difference time domain (FDTD) method can be employed to pursue these issues with adequate modeling of thin slots. Subcellular FDTD algorithms for modeling thin slots in conductors have previously been developed. One algorithm based on a quasistatic approximation has been shown to agree well with experimental results for thin slots in planes. This FDTD thin-slot algorithm is compared herein …

Investigation Of Internal Partitioning In Metallic Enclosures For Emi Control, S. Radu, Min Li, Joe Nuebel, David M. Hockanson, Yun Ji, James L. Drewniak, Todd H. Hubing, Thomas Van Doren

Electrical and Computer Engineering Faculty Research & Creative Works

High clock frequencies and short-edge rates in present high-speed digital systems result in EMI problems at increasingly higher frequencies. At these speeds, clock harmonics have sufficient energy in the range above 500 MHz to excite cavity modes of a conducting enclosure, and to drive even small length slots and apertures that are unavoidable in a practical design, and can result in an EMI problem. One approach to mitigate these problems is to partition the enclosure into several smaller internal shielded compartments. To study the factors which affect this partitioning, a special enclosure that can be divided into two internal compartments …

Investigation Of Split Groundplanes At The Connector For Emi Control, David M. Hockanson, James L. Drewniak, Joe Nuebel, James C. Parker Jr.

Electrical and Computer Engineering Faculty Research & Creative Works

EMI can often be reduced by selectively filtering various parts of a given system. One common method employed by designers is to split the groundplane near the chassis and route I/O lines over the split. The rationale is based on providing a large series impedance to common-mode currents on the I/O lines. In this manner, PCB designers hope to lower the level of noise currents contributing to radiation. This work studies the efficacy of the groundplane split as a deterrent for EMI associated with I/O lines being driven against other extended reference structures. A test-board was developed to analyze the …

Gallium Desorption Behavior At Algaas/Gaas Heterointerfaces During High-Temperature Molecular Beam Epitaxy, K. Mahalingam, D. L. Dorsey, K. R. Evans, Rama Venkat

Electrical & Computer Engineering Faculty Research

A Monte Carlo simulation study is performed to investigate the Ga desorption behavior during AlGaAs-on-GaAs heterointerface formation by molecular beam epitaxy. The transients in the Ga desorption rate upon opening the Al shutter are shown to be associated with the concurrent reduction in the V/III flux ratio. Monte Carlo simulations employing a constant V/III flux ratio yield a “steplike” variation in the Ga desorption rate with the resulting interfaces closer in abruptness to the ideal AlGaAs-on-GaAs interface. Further details on the stoichiometry of the interface and its relationship with predicted Ga desorption profiles is presented.

A Unified Green's Function Analysis Of Complicated Dfb Lasers, Jim D. Freeze, Michael A. Jensen, Richard H. Selfridge

Faculty Publications

An efficient full-wave analysis technique for one-dimensional optical domains, known as the recursive Green's function method (RGFM), is presented for evaluation of distributed feedback (DFB) laser cavities with arbitrary material profiles. The method first constructs the Green's function of an inhomogeneous domain and subsequently uses Green's theorem to determine the laser optical field, lasing wavelength, and threshold gain. The technique is applied to investigate the performance of three DFB laser structures: a chirped-grating configuration, a modulated stripe width design, and a reduced duty cycle complex-coupled device. These structures are evaluated in terms of their single-mode lasing behavior and the uniformity …

Improved Biquad Structures Using Double-Output Transconductance Blocks For Tunable Continuous-Time Filters, Vladimir I. Prodanov, Micheal M. Green

Electrical Engineering

A family of g_m −C biquad structures is derived. These biquads require only a pair of grounded capacitors and three transconductors. It is shown that a pair of complex zeros can be realized simply by replicating the output stage of the transconductance block, thereby constructing a second output current that is proportional to the original output current. Although these biquad structures are very compact, they allow independent programming of the filter’s center frequency and Q. IC simulations and measurements are presented using a fifth-order tunable filter as an example.

Research Related To Multi Degree Of Freedom Magnetic Suspensions, Yan Yang

Mechanical & Aerospace Engineering Theses & Dissertations

This thesis covers the activities associated with 1) recommissioning of the 6-inch Magnetic Suspension and Balance System (MSBS) and 2) enhancing the Annular Suspension and Pointing System (ASPS). These activities continue the program of research in the multi degree of freedom magnetic suspension program at Old Dominion University. The 6-inch MSBS is a large gap magnetic suspension system used as a model support and balance system in wind tunnels. The first stage of recommissioning of the 6- inch MSBS for the 6-inch subsonic wind tunnel is performed. Experimental data and computational results for the magnetic field distribution of the MSBS …

High-Performance Input/Output Circuit For Cmos Integrated Circuit Interface, Chee How Lim

Dissertations and Theses

In recent years, strong demand for high-performance electronic products has fueled the need for high-speed and high-integration VLSI circuits. This demand is expected to continue growing in the future, which will lead to development of IC's that are much more compact and operate at higher frequencies. As a result, preserving signal integrity for proper IC communications becomes an increasingly difficult challenge.

In this thesis, an understanding of IC noise in relation to IC packaging is sought. An IC package is modeled with sophisticated 3-D simulators to extract its corresponding parasitics. These parasitics, expressed in terms of resistance, inductance, and capacitance …

Joint-Transform Correlator Architecture For Wavelet Feature Extraction, Samuel Peter Kozaitis, Mark A. Getbehead, Wesley E. Foor

Electrical Engineering and Computer Science Faculty Publications

A version of an image consisting of multiple wavelet scales allows for more flexible feature extraction when compared to the use of one wavelet scale. We proposed an imaging system based on a multiple-input joint-transform correlator, that could be used for multiple wavelet-scale analysis of an input image. Given a single input image and wavelet, for m wavelet scales, m versions of the wavelet and m copies of the input image were generated using conventional optics that are used as inputs to a joint wavelet-transform correlator. The output consisted of 4 m - 1 correlation results, one of which is …

Development Of A Photon Counting System For Ozone Differential Absorption Lidar Signal Detection, Bradley Allen Eccles

Electrical & Computer Engineering Theses & Dissertations

A photon counting system was assembled and integrated into an existing ozone differential absorption lidar signal detection system to improve the range of ozone measurement. Results of data extraction from decaying ozone return signals are presented. Photomultiplier tube detector models EMI 9214Q and EMI 9B17Q are evaluated and characterized. Detector operating performance was based on tube quantum efficiency, gain, dark current, and linearity. The influence of photomultiplier tube characteristics on photon counting performance are discussed along with the recommended optimum photon counting operating conditions. Two photomultiplier gating schemes, focus grid and four dynode gating, are described for use in photon …

Electromyography (Emg) Signal Classification By Artificial Neural Networks, Behnam Dashtipour

Electrical & Computer Engineering Theses & Dissertations

EMG signal processing is one of the active fields of biomedical signal processing. One unanswered question is how to determine whether a muscle is fatigued by analyzing the EMG signal. Fatigue detection could be useful in several different practical situations. There are several studies which show there are differences between EMG signal features before fatigue and after fatigue. Generally studies are based on an analytical analysis of the EMG signal instead of a quantitative analysis. In all previous studies in EMG signal processing for fatigue/nonfatigue detection, the result is that there exist some differences between the EMG signal before muscle …

A Piezoresistive Metal Thin Film Tilt Sensor, Todd Allan Lindley

Electrical & Computer Engineering Theses & Dissertations

Thin film strain gauges have many applications as transducers for monitoring pressure, vibration, and acceleration. In this thesis, a simple system, consisting of a Nichrome thin film strain gauge deposited on a glass substrate, is investigated in detail. Finite element analysis is used to model the expected sensor behavior. The substrate is shaped to exhibit a constant strain distribution, and is set up in a cantilever beam configuration. R. F. sputtering is used to deposit the Nichrome film, and the resistor pattern is transferred via photolithography. The gravitational force on a mass attached to the free end of the sensor …

Determination Of The Interfacial Magneto-Optical Effects In Co/Pt Multilayer Structures, Xiang Gao, Daniel W. Thompson, John A. Woollam

Department of Electrical and Computer Engineering: Faculty Publications

In this letter, we present results of a study of the magneto-optical Kerr response in Co/Pt superlattices by solving for optical constants and Voigt parameters of constituent layers in the structure. The absolute values of the Voigt parameters of Co/Pt interfaces were found to be about twice as large as for the Co layer in the superlattice. Furthermore, using the determined optical constants and Voigt parameters, we can generate the Kerr rotations and ellipticities for Co/Pt superlattices or sandwich structures with continuously changed layer thicknesses and different repeat numbers. Comparison of these theoretical results to the experimental magneto-optical responses for …

The Application Of Wavelet-Based Least Mean Square Algorithm In Adaptive Beamforming, Shun-Hsyung Chang, Chin-Chang Chang

Journal of Marine Science and Technology–Taiwan

Wavelet transform is one of methods that utilizes the dilation and contraction of prototype wavelet basis function to form a set of fully flexible windows in the time-frequency plane. It exhibits a good effect in both the analysis of high and low frequency components of signal. By applying such a transform method to traditional least-mean-square algorithm (LMS), we can obtain an orthogonally transformed signal from a time-domain input signal after imposing wavelet transform on it. In addition, we can improve the convergence speed of learning curve by passing the transformed signal through weight which is adapted with LMS. The improved …

Computerized Shortest Path Searching For Vessels, Gene Eu Jan, Ming-Bo Lin, Yung-Yuan Chen

Journal of Marine Science and Technology–Taiwan

The solution of "computerized shortest path searching for vessels" is presented in the paper. In the core of the method, the shortest path algorithm on the raster plane with O(N?) time was applied with dedicated database structure and searching rules. Furthermore, we can extend the method to the optimal path searching for Search and Rescue (SAR) and Vessel Traffic Management System (VTMS) by modifying the database and searching rules.

Design Techniques And Paradigms Toward Design Of Low-Voltage Cmos Analog Circuits, Vladimir I. Prodanov, Michael M. Green

Electrical Engineering

Techniques for the design of robust low-voltage CMOS analog circuits are given. It is shown that both Vt-independence and proper alignment between the input and output swings are crucial for effective design of low-voltage circuits.

Achieving Cochannel Interference Objectives Over Selected Topologies In The Portland Oregon Cellular Network, David A. Wand

Dissertations and Theses

Wireless cellular mobile communications is a rapidly growing global technology which places increasing demands on a limited electromagnetic radio frequency spectrum. However, in North America only a 25 MHz block of spectrum has been allocated to each of two service providers. This must be utilized for all services offered within their assigned market.

The wireless cellular link from the mobile or portable phone to terrestrial base stations utilize this limited frequency spectrum. This is divided into 416 two-way channels, each 30 kHz in width, a subset of which is assigned to each base station. As more base stations are constructed, …

Erp Analysis Using Matched Filtering, Correlation Coefficient And Mann-Whitney Test, Yun Yan

Dissertations and Theses

Event related potentials (ERPs) carry very important information that relate to the performance of the brain functions of a human being. Further studies have identified that the late positive complex (LPC) are affected by the memory process.

The matched filter method is used to improve the signal-to-noise ratio of signal ERPs. We use the output of the matched filter to distinguish the difference of the waveforms. In our study, we found that the peak values of the matched filter output differed among normal subjects and memory-impaired subjects.

The correlation coefficient is a statistical value that can be applied to find …

The Column Multiplicity Problem In Decomposition Of Functions And Relations, Rahul Malvi

Dissertations and Theses

Finding the column multiplicity in Functional Decomposition has been known to be one of the most important problems to be solved in the process of functional decomposition of discrete functions. A lot of research has been done in this field with many new heuristics generated to find the column multiplicity, but there has not been an evaluation of the algorithms on the kinds of graphs that occur in decomposition and whether having an exact method to calculate the column multiplicity is useful from the overall design goals.The intent of this thesis was to investigate the column multiplicity problem, in order …

Diffraction Analysis And Tactical Applications Of Signal Propagation Over Rough Terrain, You-Cheol Jang

Theses and Dissertations

The free space propagation model is inadequate to predict the mean path-loss in ground wireless communication. Also, many existing propagation channel models do not adequately predict path-loss in rough terrain because most of them were based on measurements in urban areas. Hence, a channel model that estimates mean path-loss over many different kinds of terrain conditions is desired. In this thesis, two new propagation channel models, Real Terrain Diffraction Model (RTDMOD) and Universal Terrain Channel Model (UTCMOD), were developed. Other geometric theory of diffraction (GTD) methods (Epstein-Peterson (EP) and Deygout (DG)) agree within 5 % from 3 MHz to 3GHz …

Robust Control Of Smart Structures Using Neural Network Hardware, Rajendra Damle, Vittal Rao, Frank J. Kern

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, the use of Intel's Electronically Trainable Analog Neural Network (ETANN) chipi80170NX for implementing single-chip robust controllers for smart structures is successfully demonstrated. Robust controllers like the linear quadratic regulator (LQR) and linear quadratic Gaussian with loop transfer recovery (LQG/LTR) are implemented in various configurations using the ETANN chip on the smart structure test article. The test article is a cantilevered plate with PZTs as actuators and shaded PVDF film as sensors. The spatially distributed sensors allow direct measurement of the states of the system enabling the implementation of the LQR controller. A two step connectionist approach is …

Optimization Considerations For Adaptive Optics Digital Imagery Systems, Robert T. Brigantic

Theses and Dissertations

This dissertation had three objectives. The first objective was to develop image quality metrics that characterize Adaptive Optics System (AOS) performance. The second objective was to delineate control settings that maximize AOS performance. The third objective was to identify and characterize trade-offs between fully and partially compensated adaptive. For the first objective, three candidate image quality metrics were considered: the Strehl ratio, a novel metric that modifies the Strehl ratio by integrating the modulus of the average system optical transfer function to a 'noise-effective-cutoff' frequency at which some specified image spectrum signal-to-noise-ratio level is attained, and the noise-effective-cutoff frequency. It …

Design, Simulation, Fabrication And Testing Of Microprobes For A New Mems Wafer Probe Card, Yanwei Zhang

Dissertations

A new type of MEMS cantilever wafer probe card consists of an array of microcantilevers individually actuated by bimorph heating to make contact with the test chip was designed and fabricated. This probe card is called the CHIPP (Conformable, High-Pin count, Programmable ) card and can be designed to contact up to 800 I/O pads along the perimeter of a 1 cm² chip with a microprobe repeat distance of ~50 µm. Each microcantilever had an internal heater and a separate electrode carrying the signal under test and contained four separate layers plus a fifth material for the contact tip …

Design Fabrication And Characterization Of High Performance In Gaas/Inp Focal Plane Array In The 1-2.6 Μm Wavelength Region, Krishna R. Linga

Dissertations

This research thesis describes a new In_xGa_1-xAs/InA_ysP_1-y/InP technology for long wavelength photodetectors and photodetector arrays. A unique and novel detector structure was designed and fabricated using Hydride Vapor Phase Epitaxy, for low leakage current photodetector arrays in the 1-2.6 µm wavelength region. Potential applications of InGaAs focal plane arrays include near-infrared spectroscopy, fluorescence, remote sensing, environmental sensing, space and astronomical applications. The unique design concepts included the step grading of InAsP layers, lower lattice mismatch between the two InAsP graded layers, lattice matched InAsP cap layer and InGaAs absorption layer, sulphur doping …

The Design And Fabrication Of A Thermal Microprobe Integrated On An Atomic Force Microscope Probe Tip, Yongxia Zhang

Dissertations

A thermal microprobe has been designed and built for high resolution temperature sensing. The thermal microprobe consists of a very-thin-film thermocouple junction confined to the very end of a low mass Atomic Force Microscope (AFM) probe tip. Essential to high resolution temperature sensing is the confinement of the thermocouple junction to a short distance at the AFM tip. This confinement is achieved by controlled photoresist coating.

Experimental prototypes have been made with the junction confined to within 0.3 µm of the tip. The couple is made of Au/Pd, and the two metals are electrically separated elsewhere by a thin insulating …

Adaptive Space-Time Processing For Digital Mobile Radio Communication Systems, Amit Shah

Dissertations

The performance of digital mobile radio communication systems is primarily limited by cochannel interference and multipath fading. Antenna arrays, with optimum combining (OC), have been shown to combat multipath fading of the desired signal and are capable of reducing the power of interfering signals at the receiver through spatial filtering. With OC, the signals received by several antenna elements are weighted and combined to maximize the output signal-to-interference-plus-noise ratio (SLNR). We derive new closed-form expressions for (1) the probability density function (PDF) of the SINR at the output of the optimum combiner, (2) the average probability of bit error rate …