Scalable diversified antirandom test pattern generation with improved fault coverage for black-box circuit testing

Pseudorandom testing is incapable of utilizing the success rate of preceding test patterns while generating subsequent test patterns. Many redundant test patterns have been generated that increase the test length without any significant increase in the fault coverage. An extension to pseudorandom testing is Antirandom that induces divergent patterns by maximizing the Total Hamming Distance (THD) and Total Cartesian Distance (TCD) of every subsequent test pattern. However, the Antirandom test sequence generation algorithm is prone to unsystematic selection when more than one patterns possess maximum THD and TCD. As a result, diversity among test sequences is compromised, lowering the fault coverage. Therefore, this thesis analyses the effect of Hamming distance in vertical as well as horizontal dimension to enhance diversity among test patterns. First contribution of this thesis is the proposal of a Diverse Antirandom (DAR) test pattern generation algorithm. DAR employs Horizontal Total Hamming Distance (HTHD) along with THD and TCD for diversity enhancement among test patterns as maximum distance test pattern generation. The HTHD and TCD are used as distance metrics that increase computational complexity in divergent test sequence generation. Therefore, the second contribution of this thesis is the proposal of tree traversal search method to maximize diversity among test patterns. The proposed method uses bits mutation of a temporary test pattern following a path leading towards maximization of TCD. Results of fault simulations on benchmark circuits have shown that DAR significantly improves the fault coverage up to 18.3% as compared to Antirandom. Moreover, the computational complexity of Antirandom is reduced from exponential O(2n) to linear O(n). Next, the DARalgorithm is modified to ease hardware implementation for on-chip test generation. Therefore, the third contribution of this thesis is the design of a hardware-oriented DAR (HODA) test pattern generator architecture as an alternative to linear feedback shift register (LFSR) that consists of large number of memory elements. Parallel concatenation of the HODA architecture is designed to reduce the number of memory elements by implementing bit slicing architecture. It has been proven through simulation that the proposed architecture has increased fault coverage up to 66% and a reduction of 46.59% gate count compared to the LFSR. Consequently, this thesis presents uniform and scalable test pattern generator architecture for built-in self-test (BIST) applications and solution to maximum distance test pattern generation for high fault coverage in black-box environment

Dynamically Controllable Integrated Radiation and Self-Correcting Power Generation in mm-Wave Circuits and Systems

This thesis presents novel design methodologies for integrated radiators and power generation at mm-wave frequencies that are enabled by the continued integration of various electronic and electromagnetic (EM) structures onto the same substrate. Beginning with the observation that transistors and their connections to EM radiating structures on an integrated substrate are essentially free, the concept of multi-port driven (MPD) radiators is introduced, which opens a vast design space that has been generally ignored due to the cost structure associated with discrete components that favors fewer transistors connected to antennas through a single port. From Maxwell's equations, a new antenna architecture, the radial MPD antennas based on the concept of MPD radiators, is analyzed to gain intuition as to the important design parameters that explain the wide-band nature of the antenna itself. The radiator is then designed and implemented at 160 GHz in a 0.13 um SiGe BiCMOS process, and the single element design has a measured effective isotropic radiated power (EIRP) of +4.6 dBm with a total radiated power of 0.63 mW. Next, the radial MPD radiator is adapted to enable dynamic polarization control (DPC). A DPC antenna is capable of controlling its radiated polarization dynamically, and entirely electronically, with no mechanical reconfiguration required. This can be done by having multiple antennas with different polarizations, or within a single antenna that has multiple drive points, as in the case of the MPD radiator with DPC. This radiator changes its polarization by adjusting the relative phase and amplitude of its multiple ports to produce polarizations with any polarization angle, and a wide range of axial ratios. A 2x1 MPD radiator array with DPC at 105 GHz is presented whose measurements show control of the polarization angle throughout the entire 0 degree through 180 degree range while in the linear polarization mode and maintaining axial ratios above 10 dB in all cases. Control of the axial ratio is also demonstrated with a measured range from 2.4 dB through 14 dB, while maintaining a fixed polarization angle. The radiator itself has a measured maximum EIRP of +7.8 dBm, with a total radiated power of 0.9 mW, and is capable of beam steering. MPD radiators were also applied in the domain of integrated silicon photonics. For these designs, the driver transistor circuitry was replaced with silicon optical waveguides and photodiodes to produce a 350 GHz signal. Three of these optical MPD radiator designs have been implemented as 2x2 arrays at 350 GHz. The first is a beam forming array that has a simulated gain of 12.1 dBi with a simulated EIRP of -2 dBm. The second has the same simulated performance, but includes optical phase modulators that enable two-dimensional beam steering. Finally, a third design incorporates multi-antenna DPC by combining the outputs of both left and right handed circularly polarized MPD antennas to produce a linear polarization with controllable polarization angle, and has a simulated gain of 11.9 dBi and EIRP of -3 dBm. In simulation, it can tune the polarization from 0 degrees through 180 degrees while maintaining a radiated power that has a 0.35 dB maximum deviation from the mean. The reliability of mm-wave radiators and power amplifiers was also investigated, and two self-healing systems have been proposed. Self-healing is a global feedback method where integrated sensors detect the performance of the circuit after fabrication and report that data to a digital control algorithm. The algorithm then is capable of setting actuators that can control the performance of the mm-wave circuit and counteract any performance degradation that is observed by the sensors. The first system is for a MPD radiator array with a partially integrated self-healing system. The self-healing MPD radiator senses substrate modes through substrate mode pickup sensors and infers the far-field radiated pattern from those sensors. DC current sensors are also included to determine the DC power consumption of the system. Actuators are implemented in the form of phase and amplitude control of the multiple drive points. The second self-healing system is a fully integrated self-healing power amplifier (PA) at 28 GHz. This system measures the output power, gain and efficiency of the PA using radio frequency (RF) power sensors, DC current sensors and junction temperature sensors. The digital block is synthesized from VHDL code on-chip and it can actuate the output power combining matching network using tunable transmission line stubs, as well as the DC operating point of the amplifying transistors through bias control. Measurements of 20 chips confirm self-healing for two different algorithms for process variation and transistor mismatch, while measurements from 10 chips show healing for load impedance mismatch, and linearity healing. Laser induced partial and total transistor failure show the benefit of self-healing in the case of catastrophic failure, with improvements of up to 3.9 dB over the default case. An exemplary yield specification shows self-healing improving the yield from 0% up through 80%.</p

Auditory streaming and bistability paradigm extended to a dynamic environment

This is the final version. Available on open access from Elsevier via the DOI in this recordData availability: All experimental data and model code are available in the github repository james-rankin/auditory-streaming: https://github.com/james-rankin/auditory-streamingWe explore stream segregation with temporally modulated acoustic features using behavioral experiments and modelling. The auditory streaming paradigm in which alternating high- A and low-frequency tones B appear in a repeating ABA-pattern, has been shown to be perceptually bistable for extended presentations (order of minutes). For a fixed, repeating stimulus, perception spontaneously changes (switches) at random times, every 2–15 s, between an integrated interpretation with a galloping rhythm and segregated streams. Streaming in a natural auditory environment requires segregation of auditory objects with features that evolve over time. With the relatively idealized ABA-triplet paradigm, we explore perceptual switching in a non-static environment by considering slowly and periodically varying stimulus features. Our previously published model captures the dynamics of auditory bistability and predicts here how perceptual switches are entrained, tightly locked to the rising and falling phase of modulation. In psychoacoustic experiments we find that entrainment depends on both the period of modulation and the intrinsic switch characteristics of individual listeners. The extended auditory streaming paradigm with slowly modulated stimulus features presented here will be of significant interest for future imaging and neurophysiology experiments by reducing the need for subjective perceptual reports of ongoing perception.Swartz FoundationEngineering and Physical Sciences Research Council (EPSRC

Pupils in the context of multiple and multidirectional migration during their obligatory schooling years

This qualitative study is about the experiences of school-age children with multiple and multidirectional migration, and about how they challenge the established conceptualisation of social and educational integration and contribute to a better understanding of globalisation and transnationalism. Reasons and ways my study participants got involved in this form of migration were elaborated on, and their experiences and the effects on their lives and educational attainments were examined. This exploration connects to the scarce research literature on the diverse forms of migration among children and delivers evidence for the importance of looking into the individual biographical experiences of school-age children in order to rethink and adapt concrete measures supporting local educational and social integration.:1. Introduction 2. Theoretical Framework 3. Secondary literature review 4. Research questions and research methods 5. Cases and Context 6. Findings of the data analysis 7. Discussion and outlook Secondary literature List of Figures and Charts Table of content for the AppendixDie Dissertation befasst sich mit Biografien von Kindern und Jugendlichen mit einer mehrfachen und mehrdirektionalen Migrationserfahrung während ihres Schulpflichtalters und diskutiert, wie diese Erfahrungen die etablierte Konzeptualisierung der sozialen und schulischen Integration herausfordern und zu einem besseren Verständnis von Globalisierung und Transnationalismus beitragen. Es wurde untersucht, aus welchen Gründen und auf welche Art und Weise meine StudienteilnehmerInnen in dieser Migrationsform involviert waren, sowie welche Auswirkungen ihre mehrfache und mehrdirektionale Migrationserfahrung auf ihr Leben und ihre Bildungskarriere hatten.:1. Introduction 2. Theoretical Framework 3. Secondary literature review 4. Research questions and research methods 5. Cases and Context 6. Findings of the data analysis 7. Discussion and outlook Secondary literature List of Figures and Charts Table of content for the Appendi

When reading music is not enough: using art song to teach memorization to bassoonists

The purpose of this project is to create a methods book for bassoonists consisting of excerpts of art songs; the book will be accompanied by written activities to reinforce concepts learned. The goal for the student will be to memorize the excerpts (with text) and develop the skills necessary to memorize music with greater facility. There is a need for this kind of methods book because an emphasis on memorization is not common with American wind players and will offer a new perspective on how to approach memorization. Memorization is an important skill because it allows a deeper understanding of the music and performance. String players, pianists, percussionists, and vocalists are expected to memorize their recitals to create a better connection between audience and performer. The loss of a physical blockade created by the music allows the musician to create a more conversant relationship with the viewer. In addition to the visual component of performance, memorized material becomes a more natural expression. The level of concentration required of a memorized performance allows the musician to surpass the written music, creating a truly exceptional experience for everyone involved. After conducting an informal survey among colleagues and peers, it became evident that wind players generally do not have confidence in their own ability to memorize music. This lack of skill has little to do with playing a wind instrument but rather a lack of practice, emphasis, and instruction. Other instruments offer memorization as a fundamental part of the learning process. Many string players attribute their memorization skills to the Suzuki Method, which includes both repetition and delayed reading as primary tenets of the method Vocalists are given the extra element of text to their memorization, which is both an additional thing to concern oneself with, but also a great aid. In 2007, a study led by Zehra Peynircioğlu proved that lyrics yielded the highest recall of more lyrics, melody, and title. This methods book will use art song for exactly this reason; adding words to the melody will help with the memorization process. The words used in this methods book will be translated into English for ease of memory for the student; the words are supposed to act as a mnemonic tool more than artistic expression. The selection of art songs will be based on tonality, contour, and repetition. The order of the songs will allow students to start with songs that have more linear lines, simulating scalar patterns that have been worked on in fundamentals, and then progress further into wider intervals and distant tonal areas. In addition to a selection of art songs, the methods book will have guided tools to help students and teachers understand what works best for each student. Each student will have a different way of internalizing the music and producing a compelling performance, which is why it is necessary to not have a fixed strategy towards a finished product. These tools will include room to write in chords, extra staff to rewrite the melody as remembered, space to draw the contour of the melody, lines to write the text, etc. There will also be an audio component to the book so students may hear the excerpt. In order to get a better idea of how people have learned in the past, I will survey a wide cross section of wind players (college-aged and older). In this survey, I will collect information on what instrument part they play, what strategies they have used to memorize for performance, and if they consider themselves successful at memorization. Collecting this data will help me understand what tools a student may want to use and develop. My readings for this project will consist of both musical and non-musical articles pertaining to memory and retention. As someone who has always appreciated a cross-discipline style of learning, I want to be able to apply non-musical memorization research and strategies to the book to give a musically unbiased viewpoint. By creating new memory associations away from the musician's livelihood, a student may have greater success achieving their goals

Front-ends para LiDAR baseados em ADC e TDC

Autonomous vehicles are a promising technology to save over a million lives each year that are lost in road accidents. However, bringing safe autonomous vehicles to market requires massive development, starting with vision sensors. LiDAR is a fundamental vision sensor for autonomous vehicles, as it enables high resolution 3D vision. However, automotive LiDAR is not yet a mature technology, and, also requires massive development in many aspects. This thesis aims to contribute to the maturity of LiDAR, focusing on sampling architectures for LiDAR front-ends. Two architectures were developed. The first is based on a pipelined ADC, available from an AD-FMCDAQ2-EBZ board. The ADC is synchronized with the emitted pulse and able to sample at 1 Gsample/s. The second architecture is based on a TDC that is directly implemented in an FPGA. It relies on a tapped delay line topology comprising 45 delay elements and on a mux-based decoder, resulting in a resolution of 50 ps. Preliminary test results show that both implementations operate correctly, and are both suitable for sampling short pulses typically used by LiDARs. When comparing both architectures, we conclude that an ADC consumes a significant amount of power, and uses many FPGA resources. However, it samples the LiDAR waveform without any loss of information, therefore enabling maximum range and precision. The TDC is just the opposite: it consumes little power, and uses less FPGA resources. However, it only captures one sample per pulse.Os veículos autónomos são uma tecnologia promissora para salvar mais de um milhão de vidas por ano, colhidas por acidentes rodoviários. Contudo, colocar veículos autónomos seguros no mercado requer inúmeros desenvolvimentos, a começar por sensores de visão. O LiDAR é um sensor de visão fundamental para veículos autónomos, pois permite uma visão 3D de alta resolução. Contudo, o LiDAR automotivo não é uma tecnologia madura, e portanto requer também desenvolvimento em vários aspectos. Esta dissertação visa contribuir para a maturidade do LiDAR, com foco em arquiteturas de amostragem para front-ends de LiDAR. Foram desenvolvidas duas arquiteturas. A primeira assenta numa ADC pipelined, por sua vez implementada numa placa de teste AD-FMCDAQ2-EBZ. A ADC opera em sincronismo com o pulso emitido, e permite capturar amostras a 1 Gsample/s. A segunda arquitetura assenta num TDC implementado diretamente numa FPGA. O TDC baseia-se numa topologia tapped delay line com 45 linhas de atraso, e num descodificador à base de multiplexers, permitindo uma resolução temporal de 50 ps. Resultados preliminares mostram que ambas as implementações operam corretamente, e são adequadas para amostrar pulsos curtos tipicamente associados a LiDAR. Em termos comparativos, a arquitectura com base numa ADC tem um consumo de potência considerável e requer uma quantidade significativa de recursos da FPGA. Contudo, esta permite amostrar a forma de onda de LiDAR sem nenhuma perda de informação, permitindo assim alcance e precisão máximos. A arquitectura com base num TDC é exatamente o oposto: tem um baixo consumo de potência e requer poucos recursos da FPGA. Contudo, permite capturar apenas uma amostra por pulso.Mestrado em Engenharia Eletrónica e Telecomunicaçõe

Quantum anomalous hall effect, domain walls, and disorder in bilayer graphene

Seit seiner Entdeckung im Jahr 2004 ist das zweidimensionale Material Graphen Gegenstand vieler theoretischer sowie experimenteller Studien, wobei außergewöhnliche mechanische und elektrische Eigenschaften entdeckt wurden. Im Vergleich zur Monolage zeichnet sich Bilagen Graphen durch ähnlich herausragende Qualitäten aus, besitzt dabei aber noch größere Vielseitigkeit, beispielsweise durch eine variierbare Bandlücke. Zudem ist Bilagen Graphen, auf Grund seiner unter gewissen Umständen nicht verschwindenden Zustandsdichte bei Ladungsneutralität, besonders anfällig für korrelierte Zustände. Diese treten durch Elektron-Elektron Wechselwirkungen auf, wobei bestimmte Symmetrien des Systems gebrochen werden und sich das Energiespektrum verändert. Theoretische Studien nennen beispielsweise fünf verwandte Quanten-Hall-Zustände, die durch Brechung der chiralen Symmetrie entstehen können und bei Ladungsneutralität miteinander konkurrieren. Obwohl nach und nach einige dieser Zustände durch die immer besser werdende Qualität der Proben experimentell bestätigt werden konnten, gibt es diesbezüglich noch viele offene Fragestellungen. Insbesondere konnte einer dieser Quanten-Hall-Zustände, die exotische „ALL“-Phase, welche eine teilweise Polarisierung der zum Transport beitragenden Ladungsträger in eine der Graphenlagen und ein orbitales magnetischen Moment aufweist, bisher noch nicht eindeutig beobachtet werden. Des Weiteren ist bisher noch weitestgehend unklar, welche der fünf Quanten-Hall-Phasen der eigentliche Grundzustand von Bilagen Graphen ist, da die bis zum jetzigen Zeitpunkt veröffentlichten Studien keine eindeutigen experimentellen Beobachtungen liefern. Neben dem Auftreten von konkurrierenden Quanten-Hall-Zuständen könnte die Existenz von Fehlern in der Stapelfolge der zwei Graphenlagen eine mögliche Erklärung für die unterschiedlichen Signaturen in Quantentransportmessungen sein. Die Detektion dieser Kristallfehler wurde erst vor Kurzem durch präzise Techniken, wie beispielsweise optische Rasternahfeldmikroskopie, ermöglicht. Obwohl schon eindrucksvoll quantisierter Ladungstransport entlang solcher Kristallfehler im Experiment gezeigt wurde, bleibt ihr Einfluss auf die bei Ladungsneutralität auftretenden Quanten-Hall-Zustände weitestgehend unerforscht. Um die aufgeführten Fragestellungen genauer zu untersuchen, werden in dieser Arbeit Quantentransportmessungen in Bilagen Graphen bei niedrigen Temperaturen präsentiert. Diese wurden an Feldeffekttransistoren, bestehend aus ultrareinem, freischwebenden Bilagen Graphen, dessen elektrische Eigenschaften durch zwei Gate-Elektroden manipulierbar sind, durchgeführt. Besonderes Augenmerk wurde dabei auf die Existenz von Fehlern in der Stapelfolge innerhalb der untersuchten Graphen Flocken gelegt. Sind diese nicht vorhanden, konnte die exotische „ALL“-Phase bei niedrigen Magnetfeldern beobachtet werden, wobei der Zustand in achtfacher Ausführung in Form eines anomalen Quanten-Hall-Effekts mit einer Leitfähigkeit von ±2 e^2 h^(-1) (e ist dabei die Elementarladung und h das Plancksche Wirkungsquantum) auftritt. Die Entdeckung stellt einen überzeugenden Nachweis für orbitalen Magnetismus in Bilagen Graphen dar und verdeutlicht, dass das vermeintlich triviale System einen anomalen Quanten-Hall-Effekt aufweist, ohne dass die Realisierung eines fragilen Moiré-Gitters notwendig ist. Außerdem wurde der Quantentransport entlang Fehlern in der Stapelfolge von Bilagen Graphen untersucht. Dabei wurde ein komplexes Zusammenspiel zwischen topologisch geschütztem Quantentransport entlang eines Kristallfehlers und Quantentransport in Randkanälen, induziert durch den Quanten-Hall-Effekt, entdeckt. Die Messungen zeigen den maßgeblichen Einfluss der häufig vorkommenden Kristallfehler und verdeutlichen, wie wichtig es ist, diesen in zukünftigen Studien zu beachten. Zuletzt wurden die Auswirkungen von Unordnung sowie Fehlern in der Stapelfolge auf den Grundzustand und auf verschiedene Phasenübergänge zwischen Zuständen mit gebrochener Symmetrie in Bilagen Graphen untersucht. Die Ergebnisse helfen schwer erklärbare Signaturen in Quantentransportmessungen aus der Literatur zu verstehen und tragen somit zur eindeutigen Identifikation des Grundzustands von Bilagen Graphen bei. Durch die hier präsentierten Ergebnisse wurden bedeutende Fortschritte im Verständnis komplexer physikalischer Phänomene in Bilagen Graphen erzielt, was zudem die Wichtigkeit weiterer experimenteller Studien an dem Material verdeutlicht.Since the discovery of graphene in 2004, the two-dimensional material has been subject of extensive theoretical and experimental research revealing exceptional electronic and mechanical properties. Bilayer graphene, while inheriting most advantages of its monolayer counterpart, provides even more tunability, e.g. due to its tunable band gap. Moreover, as consequence of the non-vanishing density of states near charge neutrality under certain circumstances, bilayer graphene is susceptible to exotic interaction-driven broken-symmetry states that modify the energetic spectrum. For example, theoretical studies propose the emergence of a family of five competing quantum Hall states at charge neutrality owing to chiral symmetry breaking. Although some of the phases have already been observed experimentally with an increasing level of device quality, bilayer graphene retains many related unanswered questions. For instance, the exotic ALL phase, a quantum anomalous Hall phase with partial layer polarization and substantial orbital moment, has not been pinpointed clearly. Moreover, it is still under debate which of the five broken-symmetry phases is the true ground state, as ambiguous experimental results have been reported from literature. Besides the emergence of competing phases, a possible cause for distinct signatures in quantum transport measurements could be the influence of stacking domain walls in bilayer graphene. Their detection has only become possible recently using precise scanning techniques such as scattering-type scanning near-field optical microscopy. Although quantum transport along such dislocations has been shown, their impact on broken-symmetry states emerging within the zero energy Landau level remains unclear. To shed light on these unexplored aspects, low-temperature transport measurements on high-quality dually gated freestanding bilayer graphene are presented in this thesis, with special attention given to any stacking domain walls present within the bilayer graphene flakes. In their absence, the exotic ALL phase, appearing as an octet of quantum anomalous Hall phases with a conductance of ±2 e^2 h^(-1) (where e is the electronic charge and h is Planck’s constant), was tracked to low magnetic fields, providing compelling evidence for orbital magnetism in bilayer graphene. The findings demonstrate that the seemingly simple Bernal-stacked bilayer graphene exhibits the quantum anomalous Hall effect without the need of fabricating delicate moiré heterostructures. In addition, the quantum transport along stacking domain walls was investigated revealing an intriguing interplay between topological valley and quantum Hall edge transport. The measurements highlight the influence of the commonly occurring stacking domain walls and demonstrate that their impact inevitably needs to be regarded in future experiments. Lastly, the role of disorder and stacking domain walls on the emergence of the spontaneously gapped ground state and various phase transitions between broken-symmetry states was examined. The results contribute to solving the debate about the ground state of bilayer graphene and help to explain related ambiguous observations in literature. All in all, the presented measurements provide major advances in understanding the complex physical phenomena in the seemingly trivial Bernal-stacked bilayer graphene and highlight the importance of continuous experimental effort

Resonant tunnelling in semiconductor heterostructures

This thesis examines the electrical transport properties of a series of n-type GaAs/(AIGa)As double barrier resonant tunnelling devices with well widths between 50 angstrem and 2400 angstrem . The current-voltage characteristics show peak-to-valley ratios as high as 25:1 and as many as seventy resonances, with clear evidence of quantum interference effects at room temperature. The application of a high magnetic field parallel to the current flow produces magnetooscillations in the transport properties which allow the sheet charge density in the accumulation layer to be determined. The energy level in the well over a wide range of bias is obtained from analysis of thermal activation of resonant tunnelling. The contributions of elastic scattering and LO phonon emission to the valley current are investigated spectroscopically with a magnetic field and two phonon modes of the (AIGa)As barrier are observed. The buildup of space charge in the quantum well at resonance leads to intrinsic bistability in the current and differential capacitance of an asymmetric structure. Magnetoquantum oscillations due to a degenerate electron gas in the well are used to measure this charge buildup and demonstrate that the tunnelling process is truly sequential. The bistability is dramatically enhanced at high magnetic fields when the lowest energy Landau level of the well can accommodate a high electron density. In a strongly asymmetric sample, a new kind of bistability is observed where the off-resonant current exceeds the resonant current due to enhancement of charge buildup by intersubband scattering. The modulation of the scattering rate by a magnetic field produces periodic oscillations in the width of the bistability. In a magnetic field applied perpendicular to the current, the resonances are broadened as a consequence of the conservation of canonical momentum. The transition from electric to magnetic quantisation in wide wells is investigated and tunnelling into interfacial Landau levels is observed. The angular dependence of the resonances is used to probe conduction band anisotropy. In a tilted field, a completely new type of magneto-oscillations is observed