• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 6
  • 2
  • 2
  • 1
  • 1
  • 1
  • Tagged with
  • 14
  • 14
  • 5
  • 3
  • 3
  • 3
  • 3
  • 3
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Indium Bump Fabrication using Electroplating for Flip Chip Bonding

Sjödin, Saron Anteneh January 2015 (has links)
Hybrid pixel detectors are widely used in many fields, including military, environment, industry and medical treatment. When integrating such a detector, a vertical connection technique called flip-chip bonding is almost the only way to realize the high-density interconnection between each pixel detector to the read-out chip. Such bonding can offer high-density I/O and a short interconnect distance, which can make the resulting device show excellent performance. Electro deposition is a promising approach to enable a low cost and high yield bump bonding process, compared with conventional sputtering or evaporation which is currently utilized for small-scale production. Due to that, Indium bumping process using electroplating is selected, as a result of which indium bump arrays with a pitch of 220 μm and a diameter of 30 μm have been fabricated using a standard silicon wafer processing. UBM (under bump metallization) for indium bumping was Ti/Ni (300 Å/ 2000 Å). It helps to increase adhesion between the wafer and the bumps and also serves as an excellent diffusion barrier both at room temperature and at 200°C. The indium is electroplated, using an indium sulfamate plating bath, and then formed into bumps through a reflow process. The reflow is made on a 200°C hot plate with a continuous flow of nitrogen over the wafer. During the reflow the indium is melted and forms into bumps due to surface tension. All the corresponding procedural processing steps and results are incorporated in this paper.
2

Scannereigene akustische Aktivierung - Eine neue Pulssequenz vereinfacht fMRT des auditiven Kortex / Scannernoise-evoked Activation - A new Pulse Sequence simplifies fMRT of the auditory Cortex

Sahmer, Peter January 2007 (has links) (PDF)
Echo-planar Imaging (EPI) erzeugt durch schnell wechselnde Gradienten beträchtliche Schallemissionen. Dies führt nachgewiesenermaßen bei funktionellen Magnet-Resonanz-Tomographie- (fMRT-) Studien zu einer Aktivierung des auditiven Systems, insofern dieses beim jeweiligen Probanden in der Lage ist zu reagieren. Sowohl für auditive wie auch für nicht-auditive Untersuchungen wurden verschiedenste Anstrengungen unternommen, diese Interferenzen zu minimieren. Anstatt den Lärm des Scanners zu reduzieren oder die Transmission des Schalls zu behindern, war es nun das Ziel, eben diesen Schall zur Aktivierung des auditiven Kortex zu benutzen und diese mit fMRT-Untersuchungen nachzuweisen. Dieses geschieht schlicht durch das Auslassen von Read-Outs aus der Gradientenfolge der Pulssequenz. Diese Pulse sind die Hauptemissionsquellen von Schall des EPI, sie verursachen sowohl den Spitzenschallpegel als auch die Grundfrequenz, welche im umgekehrten Verhältnis zum Echo-Spacing steht. Durch eine Modell-gestützte Analyse wird gezeigt, dass das Auslassen von Read-Outs nach einem vordefinierten Schema verlässlich dazu geeignet ist, eine hämodynamische Blood-Oxygenation-Level-Dependent- (BOLD-) Signalveränderung im auditiven Kortex von normal hörenden Probanden (n=60) zu evozieren. Um den Nutzen der Technik beim auditiven fMRI zu zeigen, werden auf der Ebene der Einzelanalysen das traditionelle Family-Wise-Error-Rate- (FWER-) korrigierte Maximum Height Thresholding mit dem Spatial Mixture Modelling (SMM) verglichen. Mit Letzterem können so in 95 % der Fälle eine adäquate, bilaterale, auditive Aktivierung nachwiesen werden, wohingegen das FWER-basierte Voxel-Thresholding nur in 72 % aller Probanden eine solche Aktivierung zeigt. Um die klinische Anwendbarkeit der Technik unter pathologischen Bedingungen zu demonstrieren, wird ein Fallbericht einer Patientin vorgestellt, die an einem schweren, beidseitigen Sensorineural Hearing Loss (SNHL) aufgrund bilateraler Large Vestibular Aqueducts (LVAs) leidet. Dabei wird eben diese Modifikation benutzt, um präoperativ vor Cochlear Implantation (CI) zu zeigen, dass ein zentrales Resthörvermögen vorhanden ist. Da die Untersuchung völlig unabhängig von der Compliance des Patienten und kein zusätzliches Zubehör zum Scanner vonnöten sind, eignet sie sich hervorragend zu auditiven Untersuchungen, um so schnell das Hörvermögen zu prüfen. Dabei funktioniert die Methode unabhängig von äußerlichen Bedingungen: Bei hörgesunden Probanden ebenso wie bei Hörgeschädigten, bei Kindern, Jugendlichen und Erwachsenen aller Altersstufen sowie unabhängig von einer Sedierung während der Untersuchung. Beide benutzten Scanner zeigten unabhängig vom Gradienten oder der verwendeten Spule ein gleiches Ergebnis. / Echo-planar Imaging (EPI) induces considerable sound emissions by steep gradient pulses. This leads evidentially to an activation of the auditory system, as much it is able to response in that particular subject. For auditory as well as non-auditory investigations, various efforts have been undertaken to minimize those interferences. Instead of reducing the scanner noise or cumbering its transmission, the goal was now to utilize it to activate the auditory cortex and detect it later on by functional magnetic resonance imaging (fMRI). This was achieved by simply omitting read-outs from the gradient train of an EPI pulse sequence. Those pulses are the primary noise determinant in EPI, they induce both the peak sound level and the fundamental frequency peak, which relates inversely to the echo spacing. By hypothesis-driven analyses it is demonstrated that withholding read-out gradients in a defined scheme reliably evokes hemodynamic Blood Oxygenation Level Dependent (BOLD) signal modulations in the auditory cortex of normal hearing subjects (n=60). To show the value of this new method, the first level analyses of the single subjects with the traditional Family-Wise-Error-Rate (FWER-) corrected Maximum Height Thresholding are compared with Spatial Mixture Modelling (SMM). This way in 95 % of all subjects an appropriate, bilateral auditory activation was detected with SMM, whereas the FWER-based Voxel-Thresholding revealed such activation in only 72 %. To show the clinical practicability of the new technique under pathological conditions the case report of a patient with severe, binaural Sensoneurinal Hearing Loss (SNHL) due to bilateral Large Vestibular Aqueducts (LVA) is presented. Thereby this modification is used to confirm residual audition prior to cochlear implantation (CI). As the investigation is totally independent of the patient's compliance and no additional equipment other than the scanner is necessary, it is suited well as a quick testing for central audition. At the same time the approach is absolutely independent from other conditions: It works with normal hearing subjects as well as with hearing impaired patients; with children, adolescents as well as adults of all age brackets and regardless of sedation during the test. Both scanners, that were used, showed independent from the gradient or the coil the same results.
3

A Readout Circuit for Piezoelectric Sensors with Digital Range-Enhancement

Huang, Wen-chi 09 August 2010 (has links)
This thesis presents a fully integratable read-out front-end for recording from piezoelectric sensors. It is proposed to periodically reset the input signal to avoid build-up of large voltages across the circuit input terminals. Digitizing the signal after buffering allows removal of the reset steps in the digital domain, thus yielding a faithful representation of the applied input force variation. Different realignment algorithms are presented in this thesis, and the measured results as well as the simulated results from a bench setup are reported which confirm a 52.5 dB dynamic range and recording of frequencies as low as 0.55 Hz. It is also shown the effect of input current leakage is reduced. The proposed system is simulated using the Cadence Spectre simulator, Synopsys HSPICE and National Instruments LabVIEW to confirm its operation. Different realignment algorithms are examined using MATLAB. The read-out circuit is further realized by 0.35 £gm 2-poly 4-metal Taiwan Semiconductor Manufacturing Company (TSMC) process technology. The chip measured results are reported and compared to the simulation. The measured implementation yields a pressure recording range of 0.4 N to 169 N, while consuming 230 £gW from 3 V supplies.
4

Realistic read-out and control for Si:P based quantum computers

Testolin, Matthew J. January 2008 (has links)
This thesis identifies problems with the current operation proposals for Si:P based solid-state quantum computing architectures and outlines realistic alternatives as an effective fix. The focus is qubit read-out and robust two-qubit control of the exchange interaction in the presence of both systematic and environmental errors. We develop a theoretical model of the doubly occupied D- read-out state found in Si:P based nuclear spin architectures. We test our theory by using it to determine the binding energy of the D- state, comparing to known results. Our model can be used in detailed calculations of the adiabatic read-out protocol proposed for these devices. Regarding this protocol, preliminary calculations suggest the small binding energy of the doubly occupied read-out state will result in a state dwell-time less than that required for measurement using a single electron transistor (SET). We propose and analyse an alternative approach to single-spin read-out using optically induced spin to charge transduction, showing that the top gate biases required for qubit selection are significantly less than those demanded by the adiabatic scheme, thereby increasing the D+D- lifetime. Implications for singlet-triplet discrimination for electron spin qubits are also discussed.
5

Automated Analysis of Automotive Read-Out Data for Better Decision Making

Saleem, Muhammad January 2011 (has links)
The modern automobile is a complex electromechanical system controlled by control systems which consist of several interdependent electronic control units (ECUs). Analysis of the data generated by these modules is very important in order to observe the interesting patterns among data. At Volvo Cars Corporation today, diagnostic read-out data is retrieved from client machines installed at workshops in different countries around the world. The problem with this data is that it does not show a clear picture as what is causing what i.e. tracking the problem. Diagnostic engineers at Volvo Cars Corporation perform routine based statistical analysis of diagnostic read-out data manually, which is time consuming and tedious work. Moreover, this analysis is restricted to basic level mainly statistical analysis of diagnostic readout data. We present an approach based on statistical analysis and cluster analysis. Our approach focused on analysing the data from a pure statistical stand-point to isolate the problem in diagnostic read-out data, thereby helping to visualize and analyse the nature of the problem at hand. Different general statistical formulae were applied to get meaningful information from large amount of DRO data. Cluster analysis was carried out to get clusters consisting of similar trouble codes. Different methods and techniques were considered for the purpose of cluster analysis. Hierarchical and non-hierarchical clusters were extracted by applying appropriate algorithms. The results obtained from the thesis work show that the diagnostic read-out data consist of independent and interdependent fault codes. Groups were generated which consist of similar trouble codes. Furthermore, corresponding factors from freeze frame data which shows significant variation for these groups were also extracted. These faults, groups of faults and factors were later interpreted and validated by diagnostic engineers.
6

Automated Analysis of Automotive Read-out Data for Better Decision Making

Saleem, Muhammad January 2011 (has links)
The modern automobile is a complex electromechanical system controlled by control systems which consist of several interdependent electronic control units (ECUs). Analysis of the data generated by these modules is very important in order to observe the interesting patterns among data. At Volvo Cars Corporation today, diagnostic read-out data is retrieved from client machines installed at workshops in different countries around the world. The problem with this data is that it does not show a clear picture as what is causing what i.e. tracking the problem. Diagnostic engineers at Volvo Cars Corporation perform routine based statistical analysis of diagnostic read-out data manually, which is time consuming and tedious work. Moreover, this analysis is restricted to basic level mainly statistical analysis of diagnostic readout data. We present an approach based on statistical analysis and cluster analysis. Our approach focused on analysing the data from a pure statistical stand-point to isolate the problem in diagnostic read-out data, thereby helping to visualize and analyse the nature of the problem at hand. Different general statistical formulae were applied to get meaningful information from large amount of DRO data. Cluster analysis was carried out to get clusters consisting of similar trouble codes. Different methods and techniques were considered for the purpose of cluster analysis. Hierarchical and non-hierarchical clusters were extracted by applying appropriate algorithms. The results obtained from the thesis work show that the diagnostic read-out data consist of independent and interdependent fault codes. Groups were generated which consist of similar trouble codes. Furthermore, corresponding factors from freeze frame data which shows significant variation for these groups were also extracted. These faults, groups of faults and factors were later interpreted and validated by  diagnostic engineers.
7

Conception et intégration d'une électronique de conditionnement pour un capteur audio à base de nano-fils de silicium / Design of read-out circuit dedicated to silicon nano-wire based audio sensor

Savary, Eric 23 April 2015 (has links)
Les microphones sont des capteurs qui permettent à nos systèmes électroniques de prendre connaissance de notre environnement acoustique en fournissant un signal électrique représentatif des vibrations de l’air. Ils sont employés dans la plupart des systèmes multimédia, mais aussi dans les appareils auditifs. Dans l’implant auditif, le microphone se substitue à l’oreille humaine capable de détecter des pressions acoustiques variants de quelque μPa à quelques Pa. Les microphones, sont en général accompagnés d’un circuit électronique spécifique qui permet leur exploitation au coeur d’un système hétérogène. Depuis les toutes premières transductions acoustique-électriques, le microphone a été perfectionné avec la mise en oeuvre de nouveau principes de transduction et l’élaboration de circuit de conditionnement plus performants. Dernièrement, l’introduction de la technologie MEMS (Micro Electro Mechanical Systems) a permis de réaliser des microphones extrêmement compacts et peu couteux. Ces travaux de recherches concernent la réalisation d’un circuit électronique dédié à l’exploitation d’un transducteur M&NEMS (Micro & Nano Electro Mechanical Systems) survenant comme une évolution du MEMS. Pour commencer l’étude, le principe de transduction et l’application du microphone sont étudiés. Les circuits existants sont examinés en détail et adaptés au transducteur M&NEMS. Les résultats potentiels sont discutés et situés dans l’application. Dans un second temps, un circuit de conditionnement spécifique est proposé. Les résultats sont présentés puis le circuit électronique dédié est intégré sur silicium. Les performances des blocs fonctionnels intégrés sont mesurées et présentées. / Microphones are sensors which allow gauging acoustic environment through an electric representation of vibrations in the air. They can be found in most multimedia equipment and in hearing aids. In this particular application, microphone substitutes a human ear which is able to sense pressure level of sound ranging from a μPa to few Pa. The read-out circuit of microphones converts physical signal from transducer into electronic signals that can be used in any heterogeneous system involving audio processing. Transducers of microphones have known successive generation of improvement. The latest refinement is related to the emergence of MEMS (Micro Electro Mechanical Systems) technology which is suitable to build compact sensor. This thesis explores the design of a readout-circuit using an innovative M&NEMS (Micro & Nano Electro Mechanical Systems) technology derived from MEMS. The thesis is structured beginning with review of existing circuits for M&NEMS microphone. A comparative study is reported considering the proposed technical specifications using simulations and a prototype was realized using discrete components. In the second phase, an innovative circuit was proposed as an ASIC solution targeting M&NEMS technology developed at CEA-LETI. The performance evaluation and the physical measurements of the proposed ASIC are detailed.
8

Novas tecnologias para detecção infravermelha de alto desempenho / Novel Technologies for High Performance Infrared Detection

Claro, Marcel Santos 26 June 2017 (has links)
Neste trabalho, foi estudado a aplicação de novas heteroestruturas semicondutoras para detecção de radiação na região do infravermelho médio. Pontos quânticos de submonocamada, detectores de cascateamento quântico e pontos quânticos de InAlAs foram testados como opção para corrigir as deficiências em responsividade, corrente de escuro e temperatura de operação, comuns nas heteroestruturas convencionais baseadas em poços quânticos e pontos quânticos de InAs obtidos no regime de crescimento Stranski-Krastanov. Também foi projetado, fabricado e testado um circuito eletrônico de leitura de sinal misto para integração com matrizes de sensores e produção de imagens. Esse tipo de circuito possui uma série de vantagens em relação aos dispositivos convencionais que costumam ser completamente analógicos. / In this work, we studied the application of new types of semiconductor heterostructures for mid-infrared detection. Submonolayer quantum dots (SML-QDs), quantum-cascade detectors (QCDs) and InAlAs quantum dots were tested as an option to circumvent the common shortcomings of responsivity, dark current and operating temperature of the usual heterestructures based on quantum wells (QWs) and InAs Stranski-Krastanov quantum dots. We also designed, fabricated and tested a mixed-signal read-out circuit aiming the fabrication of focalplane arrays (FPAs) for applications to infrared imaging. This kind of architecture has several advantages over a fully analog design.
9

Novas tecnologias para detecção infravermelha de alto desempenho / Novel Technologies for High Performance Infrared Detection

Marcel Santos Claro 26 June 2017 (has links)
Neste trabalho, foi estudado a aplicação de novas heteroestruturas semicondutoras para detecção de radiação na região do infravermelho médio. Pontos quânticos de submonocamada, detectores de cascateamento quântico e pontos quânticos de InAlAs foram testados como opção para corrigir as deficiências em responsividade, corrente de escuro e temperatura de operação, comuns nas heteroestruturas convencionais baseadas em poços quânticos e pontos quânticos de InAs obtidos no regime de crescimento Stranski-Krastanov. Também foi projetado, fabricado e testado um circuito eletrônico de leitura de sinal misto para integração com matrizes de sensores e produção de imagens. Esse tipo de circuito possui uma série de vantagens em relação aos dispositivos convencionais que costumam ser completamente analógicos. / In this work, we studied the application of new types of semiconductor heterostructures for mid-infrared detection. Submonolayer quantum dots (SML-QDs), quantum-cascade detectors (QCDs) and InAlAs quantum dots were tested as an option to circumvent the common shortcomings of responsivity, dark current and operating temperature of the usual heterestructures based on quantum wells (QWs) and InAs Stranski-Krastanov quantum dots. We also designed, fabricated and tested a mixed-signal read-out circuit aiming the fabrication of focalplane arrays (FPAs) for applications to infrared imaging. This kind of architecture has several advantages over a fully analog design.
10

Development of a prototype detector for MeV gamma-ray detection on a CubeSat

Lucchetta, Giulio 18 May 2022 (has links)
Trotz der beeindruckenden Fortschritte, die die Röntgen- und Gammastrahlenobservatorien in den letzten Jahrzehnten erzielt haben, ist der Energiebereich zwischen 200 keV und 50 MeV nach wie vor kaum erforscht. Diese Lücke, die in der Literatur oft als ``MeV-Lücke'' bezeichnet wird, ist nicht auf einen Mangel an überzeugender Wissenschaft zurückzuführen, sondern auf technische Herausforderungen und Nachweisschwierigkeiten, die mit MeV-Beobachtungen einhergehen. COMPTEL an Bord von CGRO (1991-2000) war das letzte Teleskop, das eine vollständige Durchmusterung des MeV-Himmels mit einer relativ bescheidenen Empfindlichkeit durchführte. Für die Zukunft sind zahlreiche Missionen vorgeschlagen worden, insbesondere AMEGO, die die Leistung von COMPTEL um mindestens eine Größenordnung verbessern sollen. Der Zeitrahmen für die Entwicklung, den Aufbau und den Start solch großer Missionen beträgt jedoch etwa 10 Jahre und ist mit erheblichen Kosten verbunden. In diesem Szenario könnte ein viel kleinerer Satellit, der sich der neuen Welle von schnellen, relativ kostengünstigen Weltraumforschungsmissionen anschließt, die durch CubeSats ermöglicht werden, in kürzerer Zeit rentabel sein. In dieser Arbeit werden die Verfügbarkeit und die Leistung eines Compton-Teleskops auf der Grundlage des CubeSat-Standards, genannt MeVCube, untersucht. Die Auswirkungen der Materialwahl und verschiedener CubeSat-Nutzlasten wurden durch Simulationen bewertet. Trotz der begrenzten Größe kann selbst ein kleines Teleskop, das auf einem CubeSat fliegt, den Energiebereich von Hunderten von keV bis zu einigen MeV mit einer Empfindlichkeit abdecken, die mit der der letzten Generation von Großmissionen wie COMPTEL und INTEGRAL vergleichbar ist. Es wurden auch experimentelle Messungen an Cadmium-Zink-Tellurid-Halbleiterdetektoren und einer für den Weltraumbetrieb geeigneten Ausleseelektronik mit geringem Stromverbrauch durchgeführt. / Despite the impressive progresses achieved both by X-ray and gamma-ray observatories in the last decades, the energy range between 200 keV and 50 MeV remains poorly explored. This gap in coverage, often referred in literature as the ``MeV gap'', is not due to lack of compelling science, but instead to technical challenges and detection difficulties that comes with MeV observations. COMPTEL, on-board CGRO (1991-2000), was the last telescope to accomplish a complete survey of the MeV-sky with a relatively modest sensitivity. Many missions have been proposed for the future, most notably AMEGO, aiming to improve COMPTEL's performance by at least one order of magnitude. However, the timescale for development, assembly and launch of such large missions is around 10 years, with substantial costs. Looking at this scenario, a much smaller satellite, joining the new wave of rapid, relatively inexpensive space science missions enabled by CubeSats, may be profitable on a shorter time-scale. This thesis evaluates the availability and performance of a Compton telescope based on the CubeSat standard, named MeVCube. The impact of material choice and different CubeSat payloads has been evaluated through simulations. Despite the limited size, even a small telescope flying on a CubeSat can cover the energy range from hundreds of keV up to few MeVs with a sensitivity comparable to that of the last generation of large-scale missions like COMPTEL and INTEGRAL. Experimental measurements on Cadmium-Zinc-Telluride semiconductor detectors and low-power read-out electronics suitable for space operation have been performed as well.

Page generated in 0.0289 seconds