Dissertations / Theses on the topic 'PCM switches'

ITC/USA 2013 Conference Proceedings / The Forty-Ninth Annual International Telemetering Conference and Technical Exhibition / October 21-24, 2013 / Bally's Hotel & Convention Center, Las Vegas, NV
Network switches are a critical component in any networked FTI data acquisition system in order to allow the forwarding of data from the DAU to the target destination devices such as the network recorder, PCM gateways, or ground station. Larger configurations require one or more switch boxes to handle aggregation, routing, filtering and synchronization via the IEEE 1588 Precision Time Protocol. However, for smaller configurations where space and weight restrictions are more stringent, a separate switch box may not be practical This paper discusses how all the essential features of an FTI network, such as flexible forwarding and filtering and IEEE 1588 synchronization, can be maintained without the need for the separate switch box thus making significant savings on weight and size and reducing cost.

Ce manuscrit représente les travaux de thèse qui traitent principalement la conception des commutateurs MEMS RF pour des circuits reconfigurables. Une solution qui résout le problème du phénomène de piégeage dans le diélectrique des commutateurs a été proposée en utilisant le diélectrique Ta/Ta2O5. Ce commutateur MEMS RF, fonctionnant à une fréquence de 20 GHz, a bien démontré un fonctionnement fiable sans l’apparition du phénomène de chargement du diélectrique. Il a également donné une grande valeur de capacité de 350 fF et un contraste capacitif élevé de 7. Ces composants ont été ensuite intégré dans la conception d’un déphaseur en réflexion qui utilise le coupleur hybride de Lange. Le déphaseur a garanti un déphasage de 180°, des faibles pertes d’insertion ainsi qu’une bonne isolation inférieure à -23 dB. D’autres commutateurs MEMS RF en Au/SiN ont également été employés dans la conception d’un déphaseur à 2 bits et un autre à 3 bits. Le déphaseur à 2 bits a démontré la possibilité d’avoir un déphasage régulier de 0°,96° et 186° avec un pas approximatif de 90°. Les commutateurs à matériaux à changement de phase PCM, conçus au sein de notre laboratoire XLIM, ont également été testés pour la conception d’un déphaseur. Ce dernier a pu atteindre les 180° déphasage avec un problème de pertes d’insertions assez conséquents. Un dernier projet qui portait sur la conception d’un Tuner d’impédance reconfigurable LC a été détaillé. Cet adaptateur d’impédance a été testé sur le transistor WolfSpeed CGH40010F et a démontré une bonne adaptation en sortie du transistor à la fréquence de travail de 5 GHz. La conception du Tuner ainsi que son intégration dans une carte PCB avec un substrat FR4 restent, cependant, des perspectives
This manuscript represents the thesis work that mainly deals with the design of RF MEMS switches for reconfigurable circuits. A solution that solves the problem of trapping phenomenon in the dielectric of the switch has been proposed using Ta/Ta2O5 dielectric. This RF MEMS switch, operating at a frequency of 20 GHz, has showed reliable operation without the occurrence of the dielectric-trapping phenomenon. It also gave a high capacitance value of 350 fF and a high capacitive contrast of seven. These components are then integrated into the design of a reflective type phase shifter using the Lange hybrid coupler. The phase shifter guaranteed a 180° phase shift, low insertion losses as well as good isolation below -23 dB.Other RF MEMS switches, using Au/SiN actuation electrode, are used in the design of a 2-bit and a 3-bit phase shifter. The 2-bit phase shifter demonstrated the ability to have a smooth phase shift of 0°, 96° and 186° with an approximate step size of 90°. The PCM phase change materials switches, designed in our XLIM laboratory, were also tested for the design of a phase shifter. The conceived circuit was able to reach the 180° phase shift with, however, high insertion losses. In the last project, we detailed a design of an LC reconfigurable impedance tuner. This impedance adapter is tested on the WolfSpeed CGH40010F transistor and demonstrated a good matching at the output of the transistor at 5 GH. The design of the tuner and its integration into a PCB card on a FR4 substrate are still, however, a matter of concern

Ces travaux de recherche portent sur la conception et la réalisation de commutateurs RF basées sur l’intégration de matériaux innovants fonctionnels tels que le dioxyde de vanadium (VO2) et les alliages de chalcogénures de types Ge2Sb2Te5 (GST) et GeTe. Le principe de fonctionnement de ces composants repose sur le changement de résistivité que présentent ces matériaux. Le VO2 possède une transition Isolant-Métal (MIT) autour de 68°C à travers laquelle le matériau passe d’un état isolant (forte résistivité) à un état métallique (faible résistivité). La transition MIT présente l’intérêt de pouvoir être initiée sous l’effet de plusieurs types de stimuli externes (thermique, électrique et optique) avec de faibles temps de commutation. Les alliages de types GST et GeTe ont la particularité de commuter réversiblement entre un état amorphe à forte résistivité à un état cristallin à faible résistivité suite à un traitement thermique spécifique. Les commutateurs à base de GST ou de GeTe présentent l'avantage de pouvoir opérer en mode bistable car le changement de résistivité présenté par ces matériaux est de type non volatile. Les composants réalisés ont de bonnes performances électriques (isolation et pertes d’insertion) sur une large bande. Nos travaux de recherche visent à proposer une solution alternative aux solutions classiques (semi-conducteurs et MEMS-RF) pour réaliser des commutateurs RF qui peuvent être par la suite utilisés dans la conception des dispositifs reconfigurables (filtres, Antennes)
This research work focuses on the design and realization of RF switches based on the integration of new materials such as vanadium dioxide (VO2), Ge2Sb2Te5 (GST) and GeTe chalcogenides alloys. The operating principle of these devices is based on the resistivity change presented by these materials. VO2 exhibits a Metal-Insulator transition (MIT) around 68°C for which the material changes from an insulating state (high resistivity) to a metallic one (low resistivity). The MIT transition can be triggered in different ways (thermally, electrically and optically) with low switching time. GST and GeTe alloys have the particularity to be reversibly switched between a high resistive-amorphous state to low resistive-crystalline state, under a specific heat treatment. Thanks to the non-volatile resistivity change presented by these materials, GST/GeTe-based switches are able to operate in bistable mode. The fabricated devices exhibit good electrical performances (insertion loss and isolation) over a broadband. The aim of our work is to propose an alternative solution to conventional technologies (semiconductors and RF-MEMS), to design RF switches that can be used afterward in the design of reconfigurable devices (filters, antennas)

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2011.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 66-67).
As the use of data continues to expand, reliance on enterprise datacenters have become more and more critical. Evaluation of modern day datacenter performance has showed that datacenter servers are severely underutilized, resulting in inefficient use of physical and software resources. In order to alleviate these concerns, datacenters must improve their resiliency, flexibility and scalability. CPU and memory virtualization are approaches that are becoming increasingly prevalent, but a major bottleneck still exists in I/O connectivity due to the physical constraints of I/O devices in a clustered system. One solution lies with the recently developed PCI Express multi-root partitionable switch. The partitionable switch is highly configurable and provides a means of altering the allocation of I/O devices amongst multiple hosts. This offers a range of unexplored possibilities to improve system flexibility. In the thesis, we investigate the feasibility of integrating and reconfiguring a PCI Express multi-root switch in a multi-host environment on a FreeBSD platform in a live system. We study modifications required of the PCI bus and system resources. We also detail the development of a device driver to handle dynamic reconfiguration of the switch and the system's PCI bus data structures.
by Heymian Wong.
M.Eng.

The most essential unit required for all the electronic devices is the Power Supply Unit (PSU). The main objective of power supply designers is to reduce the size, cost and weight, and to increase the power density of the converter. There is also a requirement to have a lower loss in the circuit and hence in the improvement of energy efficiency of the converter circuit. Operating the converter circuits at higher switching frequencies reduces the size of the passive components such as transformers, inductors, and capacitors, which results in a compact size, weight, and increased power density of the converter. At present the switching frequency of the converter circuit is limited due to the increased switching losses in the existing semiconductor devices and in the magnetic area, because of increased hysteresis and eddy current loss in the core based transformer. Based on continuous efforts to improve the new semi conductor materials such as GaN/SiC and with recently developed high frequency multi-layered coreless PCB step down power transformers, it is now feasible to design ultra-low profile, high power density isolated DC/DC and AC/DC power converters. This thesis is focussed on the design, analysis and evaluation of the converters operating in the MHz frequency region with the latest semi conductor devices and multi-layered coreless PCB step-down power and signal transformers. An isolated flyback DC-DC converter operated in the MHz frequency with multi-layered coreless PCB step down 2:1 power transformer has been designed and evaluated. Soft switching techniques have been incorporated in order to reduce the switching loss of the circuit. The flyback converter has been successfully tested up to a power level of 10W, in the switching frequency range of 2.7-4 MHz. The energy efficiency of the quasi resonant flyback converter was found to be in the range of 72-84% under zero voltage switching conditions (ZVS). The output voltage of the converter was regulated by implementing the constant off-time frequency modulation technique. Because of the theoretical limitations of the Si material MOSFETs, new materials such as GaN and SiC are being introduced into the market and these are showing promising results in the converter circuits as described in this thesis. Comparative parameters of the semi conductor materials such as the vi energy band gap, field strengths and figure of merit have been discussed. In this case, the comparison of an existing Si MOSFET with that of a GaN MOSFET has been evaluated using a multi-layered coreless PCB step-down power transformer for the given input/output specifications of the flyback converter circuit. It has been determined that the energy efficiency of the 45 to 15V regulated converter using GaN was improved by 8-10% compared to the converter using the Si MOSFET due to the gate drive power consumption, lower conduction losses and improved rise/fall times of the switch. For some of the AC/DC and DC/DC applications such as laptop adapters, set-top-box, and telecom applications, high voltage power MOSFETs used in converter circuits possess higher gate charges as compared to that of the low voltage rating MOSFETs. In addition, by operating them at higher switching frequencies, the gate drive power consumption, which is a function of frequency, increases. The switching speeds are also reduced due to the increased capacitance. In order to minimize this gate drive power consumption and to increase the frequency of the converter, a cascode flyback converter was built up using a multi-layered coreless PCB transformer and this was then evaluated. Both simulation and experimental results have shown that with the assistance of the cascode flyback converter the switching speeds of the converter were increased including the significant improvement in the energy efficiency compared to that of the single switch flyback converter. In order to further maximize the utilization of the transformer, to reduce the voltage stress on MOSFETs and to obtain the maximum power density from the power converter, double ended topologies were chosen. For this purpose, a gate drive circuitry utilising the multi-layered coreless PCB gate drive transformer was designed and evaluated in both a Half-bridge and a Series resonant converter. It was found that the gate drive power consumption using this transformer was less than 0.8W for the frequency range of 1.5-3.5MHz. In addition, by using this gate drive circuitry, the maximum energy efficiency of the series resonant converter was found to be 86.5% with an output power of 36.5W.

Thulium fiber lasers have attracted interest based on their long emission wavelength and large bandwidth (~1.8 – 2.1 &"181;m) relative to more established ytterbium and erbium fiber lasers. In addition, Tm:fiber lasers offer the potential for high efficiencies (~60 %) and high output power levels both in cw as well as pulsed regimes. These attributes are useful particularly in applications such as remote sensing, materials processing and mid-infrared generation. This dissertation describes the development of novel nanosecond pulsed thulium fiber laser systems with record high peak power levels in order to pump nonlinear mid-infrared generation. The peak power scaling in thulium fiber lasers requires new fiber designs with ultra large mode field area (MFA). Two different classes of prototype thulium doped photonic crystal fibers (PCF) were investigated for high peak power generation. The first prototype is a flexible-PCF with 50 ?m core diameter, and the second is a rod-type PCF with 80 ?m diameter core. A robust single stage master oscillator power amplifier (MOPA) source based on flexible-PCF was developed. This source provided narrow linewidth, tunable wavelength, variable pulse duration, high peak power, and high energy nanosecond pulses. The PCF-rod was implemented as a second stage power amplifier. This system generated a record level of ~1 MW peak power output with 6.4 ns pulse-duration at 1 kHz repetition rate. This thulium doped PCF based MOPA system is a state of the art laser source providing high quality nanosecond pulses. The single stage MOPA system was successfully implemented to pump a zinc germanium phosphide (ZGP) crystal in an optical parametric oscillator (OPO) cavity to generate 3 - 5 &"181;m wavelengths. The MOPA source was also used to demonstrate backside machining in silicon wafer. The PCF based laser system demonstrated an order of magnitude increase in the peak power achievable in nanosecond thulium doped fiber laser systems, and further scaling appears possible. Further increases in the peak power will enable additional capabilities for mid-IR generation and associated applications.
Ph.D.
Doctorate
Optics and Photonics
Optics and Photonics
Optics

Les travaux présentés dans ce manuscrit portent sur la conception, simulation et réalisation des nouvelles structures des commutateurs hyperfréquences basées sur l’intégration des couches minces des matériaux innovants fonctionnels tels que les matériaux à changement de phase (PCM) et les matériaux à transition de phase (PTM). Le principe de fonctionnement de ces composants repose sur le changement de résistivité présenter par ces matériaux. Nous avons exploité le changement de résistivité réversible du GeTe de la famille des matériaux à changement de phase (PCM) entre les deux états : amorphe à forte résistivité et cristallin à faible résistivité, pour réaliser une nouvelle structure d’un simple commutateur SPST. Ensuite, nous avons intégré ce commutateur dans une nouvelle structure de la matrice de commutation DPDT (Double Port Double Throw) à base de PCM pour l’application dans la charge utile du satellite. Nous avons utilisé la transition isolant-métal présenté par le dioxyde de vanadium (VO2) de la famille des matériaux à transition de phase, pour réaliser une nouvelle structure de commutateur simple à deux terminaux sur une très large bande de fréquence (100 MHz–220 GHz)
The work presented in this manuscript focuses on the design, simulation and realization of new microwave switches structures based on the integration of thin layers of innovative functional materials such as phase change materials (PCM) and phase transition materials. (PTM). The operating principle of these components is based on the change of resistivity present by these materials. We exploited the reversible resistivity change of GeTe of phase change materials family between the two states: amorphous with high resistivity and crystalline with low resistivity to realize a new structure of SPST switch. Then, we have integrated this switch structure on a new structure of DPDT (Double Port Double Throw) switch matrix based on phase change materials for application in satellite payload. We have used the insulatingmetal transition presented by the vanadium dioxide (VO2) of phase transition materials family to realize a new two terminals simple switch structure on a very wide frequency band (100 MHz–220 GHz)

The Power Supply Unit (PSU) plays a vital role in almost all electronic equipment. The continuous efforts applied to the improvement of semiconductor devices such as MOSFETS, diodes, controllers and MOSFET drivers have led to the increased switching speeds of power supplies. By increasing the switching frequency of the converter, the size of passive elements such as inductors, transformers and capacitors can be reduced. Hence, the high frequency transformer has become the backbone in isolated AC/DC and DC/DC converters. The main features of transformers are to provide isolation for safety purpose, multiple outputs such as in telecom applications, to build step down/step up converters and so on. The core based transformers, when operated at higher frequencies, do have limitations such as core losses which are proportional to the operating frequency. Even though the core materials are available in a few MHz frequency regions, because of the copper losses in the windings of the transformers those which are commercially available were limited from a few hundred kHz to 1MHz. The skin and proximity effects because of induced eddy currents act as major drawbacks while operating these transformers at higher frequencies. Therefore, it is necessary to mitigate these core losses, skin and proximity effects while operating the transformers at very high frequencies. This can be achieved by eliminating the magnetic cores of transformers and by introducing a proper winding structure. A new multi-layered coreless printed circuit board (PCB) step down transformer for power transfer applications has been designed and this maintains the advantages offered by existing core based transformers such as, high voltage gain, high coupling coefficient, sufficient input impedance and high energy efficiency with the assistance of a resonant technique. In addition, different winding structures have been studied and analysed for higher step down ratios in order to reduce copper losses in the windings and to achieve a higher coupling coefficient. The advantage of increasing the layer for the given power transfer application in terms of the coupling coefficient, resistance and energy efficiency has been reported. The maximum energy efficiency of the designed three layered transformers was found to be within the range of 90%-97% for power transfer applications operated in a few MHz frequency regions. The designed multi-layered coreless PCB transformers for given power applications of 8, 15 and 30W show that the volume reduction of approximately 40-90% is possible when compared to its existing core based counterparts. The estimation of EMI emissions from the designed transformers proves that the amount of radiated EMI from a three layered transformer is less than that of the two layered transformer because of the decreased radius for the same amount of inductance. Multi-layered coreless PCB gate drive transformers were designed for signal transfer applications and have successfully driven the double ended topologies such as the half bridge, the two switch flyback converter and resonant converters with low gate drive power consumption of about half a watt. The performance characteristics of these transformers have also been evaluated using the high frequency magnetic material made up of NiZn and operated in the 2-4MHz frequency region. These multi-layered coreless PCB power and signal transformers together with the latest semiconductor switching devices such as SiC and GaN MOSFETs and the SiC schottky diode are an excellent choice for the next generation compact SMPS.

Nowadays, major public concern is concentrated on reducing the usage of fossil fuels and reducing emissions of CO2 by different energy advancement. Electric vehicle technology presents extremely effective way of reducing carbon emissions and paves the way of having sustainable and renewable energy future. In order to wear the cost of electric vehicles down, batteries have to be improved as well as higher power density and high reliability has to be achieved. This research work mainly focuses on achieving higher power density and higher reliability of the inverter stage by utilizing wide-bandgap SiC MOSFET semiconductor devices in electric vehicle application. In order to achieve higher reliability of the inverter stage, high bandwidth, high performance Rogowski coil switch current sensors are employed. These sensor were embedded on the PCB and integrated on the gate driver. High bandwidth switch current sensor measurement is used for fast short-circuit detection and protection of the SiC MOSFET semiconductor switches. Furthermore, comparison with conventional detection and protection method used in automotive IGBT applications is shown where novel protection showed superior performance. This thesis also shows principle of how to obtain phase currents of the system using Rogowski coil switch current sensor measurements. Digital reconstruction principle is employed to obtain the phase currents. Accurate and linear current sensor is achieved. By successfully realizing this integrated phase current measurement on the gate driver, elimination of the commercial current sensors from the system is possible. By eliminating existing phase current sensors, higher power density could be achieved. Sensor is evaluated in both continuous and discontinuous PWM schemes.
Master of Science
Together with renewable sources, electric vehicle will play an important role as a part of sustainable and renewable energy future by significantly reducing emissions of CO2 into the atmosphere. In order to make electric cars more acceptable and accessible and make a significant impact on the environment, cost must be lowered down. To wear the cost of the electric vehicles down, powertrain of the car must be significantly improved and made smaller as well as lighter. This thesis mainly focuses on improving the reliability of the motor driving stage by implementing novel protection during fault periods such as short-circuit event. Furthermore, this novel protection allows current sensing that is crucial for motor control during normal operation periods. This will enable more compact motor driving stage since existing current sensing elements can be eliminated.

Il documento illustra il lavoro di analisi dei requisiti, progettazione, implementazione e valutazione di un sistema per l’autenticazione degli utenti delle workstation della sede di Scienze del Dipartimento di Informatica — Scienza ed Ingegneria (DISI) che si integri al sistema di autenticazione d’Ateneo. Il sistema descritto è entrato in produzione il 24 settembre 2014 ed è tuttora operante. Il lavoro percorre le modalità di gestione degli account utente in uso presso il DISI e le nuove modalità di organizzazione del DSA d’Ateneo discutendo le motivazioni per cui le soluzioni standard non possono essere adottate nel caso esposto. Analizzato il processo di login dei sistemi Unix e le librerie coinvolte verrà esposto il nuovo progetto, le particolarità dello sviluppo delle nuove librerie PAM e di Name Service Switch e la loro modalità di funzionamento e configurazione all’interno del cluster Unix. In conclusione vengono presentate una serie di valutazioni che mostrano i vantaggi e il rispetto dei requisiti della nuova implementazione.

In recent years, IP based end-to-end services have grown in popularity. Efficiently meeting the user demand for such services, different techniques for traffic engineering transport networks have been developed. One such technique, currently being developed for multilayered networks, is Generalized Multi-Protocol Label Switching (GMPLS). GMPLS is a necessary networking technique because provisioning end-to-end services will today, and in the foreseeable future, very likely require the co-operation of multiple network layers. Here, the readiness of GMPLS for optical networks is investigated by reviewing the current support for optical networking components in the GMPLS standard documents. Based on this investigation, a candidate solution for routing and constraint-based path computation in optical network segments has been derived. This candidate solution is shown to efficiently handle the additional attributes and constraints inherent in optical networking components.
De senaste åren har IP-baserade tjänster ökat i popularitet. För att effektivt möta de användarkrav som ställs på sådana tjänster har olika tekniker för att styra transportnätverk utvecklats. En sådan teknik, nu under utveckling för multi-lagrade nätverk, är GMPLS. GMPLS är en nödvändig nätverksteknik eftersom tillhandahållandet av sluttjänster mellan olika användare idag, och inom en överskådlig framtid, mycket sannolikt kommer att kräva samarbete mellan flera nätverkslager. Här undersöks GMPLS färdighet i optiska nätverk genom att se över det nuvarande stödet för optiska nätverkskomponenter i GMPLS standarddokument. Baserat på denna undersökning har en kandidatlösning för routing och begränsad vägberäkning i optiska nätverkssegment tagits fram. Denna kandidatlösning visas effektivt hantera de ytterligare attribut och restriktioner som existerar i optiska nätverkskomponenter.

The design of series-loaded resonant converters using the state of the art SiC power transistorsis investigated in the thesis. SiC devices are chosen as they offer lower switching losses comparedto conventional Si based devices A very detailed study about the working and differentmodes of operation of the resonant converter is carried out. The thesis further explains how thehigh speed switching capabilities of the SiC devices remain untapped owing to the presence ofstray inductances in the switch-snubber layout. A comparison of all the commercially availableSiC devices are carried out to find the most suitable switch for the resonant converter. Thethesis also carries out a very detailed step by step design of the circuit and the PCB layout forthe resonant converter. Two different layouts are proposed and then compared for their strayinductance and power losses. Finally, based on the experiments the thesis validates the suitabilityof using discrete SiC power transistors in place of power modules.
Utformningen av serie-belastade resonansomvandlare med hjälp av toppmoderna SiC högeffekttransistorernaundersöks i denna avhandlingen. SiC-enheter väljs eftersom de erbjuderlägre switch-förluster jämfört med konventionella Si-baserade enheter.En mycket detaljeradstudie om funktionen och de olika operationella tillstånden hos resonansomvandlare utförs.Avhandlingen förklarar vidare hur förmågan till högfrekvent switchning hos SiC-enheterförblir ofullständigt utnyttjad på grund av förekomsten av ströinduktanser i switch-snubberlayouten.En jämförelse av alla kommersiellt tillgängliga SiC-enheter genomförs för att hittaden mest lämpliga switchen för resonansomvandlaren. Avhandlingen utförs också en mycketdetaljerad steg-för-steg-utformning av resonansomvandlaren kretsschema och kretskortlayout.Två olika layouter föreslås och jämförs därefter utifrån deras ströinduktanser ocheffektförluster. Slutligen, baserat på experimentella resultat bekräftar avhandlingen.Lämpligheten att använda diskreta SiC-effekttransistorer istället för effektmoduler medintegrerade drivarsteg för styrelektroderna.

L'intégration des nouveaux éléments basés sur la physique des plasmas dans le domaine des circuits et des systèmes micro-ondes est l'objectif de ce travail. En profitant des caractéristiques électromagnétiques des plasmas et en jouant sur leur architecture, on développe des micro-commutateurs micro-ondes et d'autres circuits radio et hyperfréquences en technologies microrubans ou en guide d'onde… La simulation de la propagation des ondes électromagnétiques dans un plasma et les études de l'interaction entre un plasma et les ondes électromagnétiques nécessite la connaissance des paramètres fondamentaux du plasma comme la permittivité. C'est pour cela qu'on étudie aussi les mesures plasmas par différents techniques comme la transmission/réflexion des ondes électromagnétiques, la perturbation des cavités résonnantes, ... Un schéma électrique équivalent modélisant un micro-commutateur hyperfréquence en plasma, est obtenu grâce aux mesures des courants de décharge électrique, à la rétro-simulation et aux techniques de modélisation numérique. Un coupleur directif hybride compact est utilisé pour les mesures plasmas en assurant la protection du matériel et de l'équipement de mesure des signaux d'un plasma.

KTH is funding a project whose goal is to send a satellite into space. This project is called MIST (Miniature Student Satellite) which is assembled by a team of students at KTH. On the satellite there are experiments that are invented by other teams, in two of those experiments a power supply is required. This thesis is a technical investigation on how to design the power supply to both of those experiments, which are called SiC and Piezo LEGS. Piezo LEGS will investigate how their nanosized motors will behave and function in a space environment. SiC will investigate how their silicone carbide transistors will be affected by the space environment. A team made of four other students was selected to produce SiC experiments and a PCB in which this work is included. A literature study was done to get a better understanding of how power supplies work and to know how to select a good power supply. When the power supplies were selected they were simulated to meet the requirements. The next step was to do a Printed Circuit Board(PCB) for the SiC experiment and Piezo LEGS to be able to test the power supplies functionality in the physical world. Both of the converters reached the required output and characteristics working on their respective PCB. More time is needed for long time testing and optimization on the PCB layouts.
MIST (Miniature Student Satellite) är ett av KTH subventionerat projekt vilket har som mål att skicka upp en satellit i rymden. Projektet kommer omfatta flera olika experiment. Piezo LEGS ska undersöka en motors funktionalitet i rymdmiljö. SiC ska undersöka hur Silicon carbide halvledare och transistorer påverkas av rymdmiljön. Båda experimenten kräver varsin strömförsörjning för att fungera. Detta projekt ska undersöka kraven på strömförsörjning samt testa prototypen av ett kretskort för densamma. Först genomfördes en förstudie av de två typer av regulatorer som vanligtvis används som strömförsörjning, den linjära regulatorn och switch-mode regulatorn för att förklara olika strömförsörjningsteknologier, samt ta reda på de olika miljökraven. Baserat på förstudiens resultat erhölls kunskap för hur tester ska tas fram för funktionalitet av regulatorerna så att de når kraven för MIST för att sedan kunna producera de båda regulatorerna. Målet är att resultatet av simuleringarna på strömförsörjningen ska stämma överens med utfallet av kretskorten som produceras. Mätningar genomfördes på prototyp kretskort som visade att simuleringarna var korrekta och gav strömförsörjningen rätt resultat på kretskorten. Några av funktionerna på regulatorerna hann ej testas på grund av tidsbrist och mycket framtida arbete kvarstår.

This paper deals with the hardware and software design of the data acquisition distributed system with large amount of connected sensors. The intended application of this work is measuring some physical quantities in the building constructions. The designed system is hierarchically divided into the three levels. On the highest level there is a single-board computer Raspberry Pi which is used as a master on RS-485 bus. There can be up to 32 slave devices on the bus while each of them collects data from the sensors connected to 4-channel I2C bus. At the same time the Raspberry Pi is used as a web server, providing the user interface of the system.

Le microscope à force atomique (AFM) permet de caractériser avec une excellente résolution spatiale les surfaces d’échantillons de différentes natures et peut être mis en œuvre dans des milieux variés. Cette versatilité a favorisé le développement d’un grand nombre de techniques dérivées, destinées à investiguer diverses propriétés physiques locales. Le LGEP a ainsi réalisé un module, le Résiscope, capable de mesurer la résistance électrique locale à la surface d’un échantillon polarisé en continu, sur une gamme de 11 décades. Mise au point en mode contact, où la pointe exerce en permanence une force sur l’échantillon, cette technique fonctionne très bien sur des matériaux durs, mais trouve ses limites sur des échantillons mous ou fragiles puisque dans certaines conditions, la pointe peut altérer leur surface. Pour de tels échantillons, un mode contact intermittent, dans lequel la pointe vient à intervalles réguliers toucher très brièvement la surface, est plus approprié, mais complique la réalisation des mesures électriques. Le but de la thèse consistait à lever cette difficulté en modifiant le Résiscope pour pouvoir l’associer au « Pulsed Force Mode », mode intermittent où la pointe oscille à une fréquence de 100Hz à 2000Hz.Différentes évolutions matérielles et logicielles ont été apportées pour permettre le suivi temporel détaillé du signal de résistance électrique à chaque établissement/rupture de contact (indispensable pour passer en revue les phénomènes liés à l’intermittence), de même que pour pouvoir travailler à des vitesses de balayage acceptables. Pour l’imagerie, les meilleurs contrastes ont été obtenus grâce à une électronique de synchronisation et de traitement prenant en compte les valeurs de résistance électrique à des moments bien précis. Pour tester ce nouveau système, nous avons dans un premier temps comparé les courbes de résistance et de déflexion que nous obtenons par ce mode avec celles considérées classiquement dans le mode approche-retrait. Nous avons ensuite étudié l’influence des principaux paramètres (fréquence et amplitude d’oscillation, force d’appui, type de pointe, etc.) sur les mesures topographiques et électriques, en utilisant le HOPG comme matériau de référence. Ces essais ont notamment permis de mettre en évidence un retard quasi systématique du signal électrique par rapport au signal de déflexion (autre que le temps de mesure propre au Résiscope), dont nous n’avons pu élucider l’origine. Une fois ces connaissances acquises, nous avons étudié deux types d’échantillons organiques, l’un à caractère académique – des monocouches auto-assemblées d’alcanethiols (SAMs), l’autre à finalité plus applicative – des couches minces formées d’un réseau interpénétré de deux constituants (P3HT:PCBM) destinées aux cellules photovoltaïques. Dans les deux cas nous avons montré la pertinence de l’outil Résiscope en mode intermittent pour obtenir des informations qualitatives et quantitatives. Parallèlement à ces travaux sur matériaux fragiles, nous avons mené une étude annexe sur un phénomène de croissance de matière à caractère isolant constaté dans des conditions particulières sur différents matériaux durs, qui a été interprété comme la formation de polymère de friction sous l’effet des nano-glissements répétés associés à la déflexion du levier.Ces travaux ont été réalisés dans le cadre d’une convention CIFRE avec la société Concept Scientifique Instruments, adossée au projet ANR « MELAMIN » (P2N 2011)
The atomic force microscope (AFM) allows to characterize with excellent spatial resolution samples of different types of surfaces and can be implemented in various environments. This versatility has encouraged the development of a large number of derivative technics, intended to investigate various local physical properties. The LGEP thus achieved a module, the Résiscope, capable of measuring the local electrical resistance on the surface of a sample polarized continuously, on a range of 11 decades. Developed in contact mode, where the tip continuously exerts a force on the sample, this technic works well on hard materials, but finds its limits on soft or fragile samples since under certain conditions, the tip can alter the surface. For such samples, an intermittent contact mode, in which the tip comes at regular intervals touch very briefly the surface, is more appropriate, but complicates the achievement of electrical measurements. The aim of this thesis was to overcome this difficulty by changing the Résiscope to be able to join the "Pulsed Force Mode", intermittent mode where the tip oscillates at a frequency of 100Hz to 2000Hz. Different hardware and software changes have been made to permit the detailed temporal monitoring of the electrical resistance signal to each make / break contact (necessary to review the phenomena related to intermittency), as well as to be able to work in acceptable scan speeds. For imaging, the best contrasts were obtained through an electronic timing and treatment taking into account the electrical resistance values at specific times.To test this new system, we have initially compared resistance and deflection curves we get by this mode with those considered classically in the force-distance curves mode. We then investigated the influence of main parameters (frequency and amplitude of oscillation, setpoint, coating of the tips, etc.) on the topographical and electrical measurements, using the HOPG as reference material. These tests resulted to highlight a nearly systematic delay of the electrical signal relative to the deflection signal (other than the Resiscope measure time), which we were not able to elucidate the origin. Once these knowledge acquired, we studied two types of organic samples, one in academic nature - Self-Assembled Monolayers of alkanethiols (SAMs), the other more applicative purpose – formed of thin layers of an interpenetrating network of two components (P3HT:PCBM) for photovoltaic cells. In both cases we have shown the relevance of the Resiscope tool in intermittent mode to obtain qualitative and quantitative information. In addition to these work on fragile materials, we conducted an annex study on a phenomenon of growth material of insulating nature found in special conditions on various hard materials, which has been interpreted as the friction polymer formation as a result of repeatedly nano-sliding associated with the deflection of the cantilever. These investigations were conducted under a CIFRE agreement with the Concept Scientific Instruments company, backed by the ANR MELAMIN» (P2N 2011) project

碩士
國立臺灣海洋大學
電機工程學系
103
In this thesis, we consider the design and simulation of a pseudo-continuous conduction mode (PCCM) buck converter. Two switches are used to implement the PCCM operation.Simulation results verify the beneifit of the used PCCM buck converter.

abstract: A new type of Ethernet switch based on the PCI Express switching fabric is being presented. The switch leverages PCI Express peer-to-peer communication protocol to implement high performance Ethernet packet switching. The advantages and challenges of using the PCI Express as the switching fabric are addressed. The PCI Express is a high-speed short-distance communication protocol largely used in motherboard-level interconnects. The total bandwidth of a PCI Express 3.0 link can reach as high as 256 gigabit per second (Gb/s) per 16 lanes. Concerns for PCI Express such as buffer speed, address mapping, Quality of Service and power consumption need to be considered. An overview of the proposed Ethernet switch architecture is presented. The switch consists of a PCI Express switching fabric and multiple adaptor cards. The thesis reviews the peer-to-peer (P2P) communication protocol used in the switching fabric. The thesis also discusses the packet routing procedure in P2P protocol in detail. The Ethernet switch utilizes a portion of the Quality of Service provided with PCI Express to ensure guaranteed transmission. The thesis presents a method of adapting Ethernet packets over the PCI Express transaction layer packets. The adaptor card is divided into the following two parts: receive path and transmit path. The commercial off-the-shelf Media Access Control (MAC) core and PCI Express endpoint core are used in the adaptor. The output address lookup logic block is responsible for converting Ethernet MAC addresses to PCI Express port addresses. Different methods of providing Quality of Service in the adaptor card include classification, flow control, and error detection with the cooperation of the PCI Express switch are discussed. The adaptor logic is implemented in Verilog hardware description language. Functional simulation is conducted in ModelSim. The simulation results show that the Ethernet packets are able to be converted to the corresponding PCI Express transaction layer packets based on their destination MAC addresses. The transaction layer packets are then converted back to Ethernet packets. A functionally correct FPGA logic of the adaptor card is ready for implementation on real FPGA development board.
Dissertation/Thesis
M.S. Electrical Engineering 2012