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Analyse expérimentale et modélisation du bruit haute fréquence des transistors bipolaires à hétérojonctions SiGe et InGaAs/InP pour les applications très hautes fréquences / Experimental analysis and modelling of high frequency noise in SiGe and InGaAs/InP heterojunction bipolar transistors for high frequency applicationsRamirez-garcia, Eloy 20 June 2011 (has links)
Le développement des technologies de communication et de l’information nécessite des composants semi-conducteurs ultrarapides et à faible niveau de bruit. Les transistors bipolaires à hétérojonction (TBH) sont des dispositifs qui visent des applications à hautes fréquences et qui peuvent satisfaire ces conditions. L’objet de cette thèse est l’étude expérimentale et la modélisation du bruit haute fréquence des TBH Si/SiGe:C (technologie STMicroelectronics) et InP/InGaAs (III-V Lab Alcatel-Thales).Accompagné d’un état de l’art des performances dynamiques des différentes technologies de TBH, le chapitre I rappelle brièvement le fonctionnement et la caractérisation des TBH en régime statique et dynamique. La première partie du chapitre II donne la description des deux types de TBH, avec l’analyse des performances dynamiques et statiques en fonction des variations technologiques de ceux-ci (composition de la base du TBH SiGe:C, réduction des dimensions latérales du TBH InGaAs). Avec l’aide d’une modélisation hydrodynamique, la seconde partie montre l’avantage d’une composition en germanium de 15-25% dans la base du TBH SiGe pour atteindre les meilleurs performances dynamiques. Le chapitre III synthétise des analyses statiques et dynamiques réalisées à basse température permettant de déterminer le poids relatif des temps de transit et des temps de charge dans la limitation des performances des TBH. L’analyse expérimentale et la modélisation analytique du bruit haute fréquence des deux types de TBH sont présentées en chapitre IV. La modélisation permet de mettre en évidence l’influence de la défocalisation du courant, de l’auto-échauffement, de la nature de l’hétérojonction base-émetteur sur le bruit haute fréquence. Une estimation des performances en bruit à basse température des deux types de TBH est obtenues avec les modèles électriques. / In order to fulfil the roadmap for the development of telecommunication and information technologies (TIC), low noise level and very fast semiconductor devices are required. Heterojunction bipolar transistor has demonstrated excellent high frequency performances and becomes a candidate to address TIC roadmap. This work deals with experimental analysis and high frequency noise modelling of Si/SiGe:C HBT (STMicroelectronics tech.) and InP/InGaAs HBT (III-V Lab Alcatel-Thales).Chapter I introduces the basic concepts of HBTs operation and the characterization at high-frequency. This chapter summarizes the high frequency performances of many state-of-the-art HBT technologies. The first part of chapter II describes the two HBT sets, with paying attention on the impact of the base composition (SiGe:C) or the lateral reduction of the device (InGaAs) on static and dynamic performances. Based on TCAD modelling, the second part shows that a 15-25% germanium composition profile in the base is able to reach highest dynamic performances. Chapter III summarizes the static and dynamic results at low temperature, giving a separation of the intrinsic transit times and charging times involved into the performance limitation. Chapter IV presents noise measurements and the derivation of high frequency noise analytical models. These models highlight the impact of the current crowding and the self-heating effects, and the influence of the base-emitter heterojunction on the high frequency noise. According to these models the high frequency noise performances are estimated at low temperature for both HBT technologies.
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Avaliação de ferramenta de simulação da transmissão sonora para projetos de isolamento acústico em edificações habitacionaisSilva, Renata Costa da 19 July 2014 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / In July, 2013, Brazil s new standard, NBR15575:2013, began to require minimum
thermal, luminal, structural and acoustical performance levels in new constructions of
residential dwellings. Thus, computer programs that simulate the sound transmission
in buildings, can serve as important tools for professionals, enabling the verification of
virtual acoustic performance of projects, quickly and economically. By being widely used
in European countries, they have the database of existing elements and building systems
in Europe. From this, this study aimed to evaluate a computational tool of simulation of
sound transmission on the reality of Brazilian buildings. Twenty households were selected
in the city of Santa Maria - RS, to be measured in situ and then simulated to airborne and
impact noise. The residences were chosen according to standard and types of building
systems. For greater representation of Brazilian buildings, residences of low, medium
and high standards were chosen. The building systems chosen were structural masonry,
structural walls with concrete or ceramic block; and reinforced concrete, with walls of
hollow brick; all with massive concrete slab. The software used for the simulations was
the SONarchitect and all the features and building elements used were entered into the
software s database. The values of Ln,T , Dn,T , and RT per frequency band, and their
weighted values Ln,T,w, Dn,T,w and mean RT were obtained through measurements and
simulation. The weighted measured and simulated values were similar, on the other hand,
the values obtained by frequency band showed disagreement with the lower frequencies
precisely, from 50 Hz to 100 Hz. There was also a relationship of impact sound transmission
loss with the area size of the partition, in which there is a significant increase in sound
insulation in partitions with larger areas. In addition, coefficients and safety factors were
determined for each standard and building system to be applied in the spectra of the
simulations, aiming to bring the simulated values closer to the measured ones. Parallel
with the evaluation of the computational tool, questionnaires with 150 professionals who
develop acoustic projects in the country were applied. This step had as main objective
to find out what tools and methods are mostly used by professionals in the development
of these projects. From 31 received responses, it was determined that 20.88% of the
professionals use a computational tool to develop designs. It was also possible to discover
some features such as field of expertise and graduation year, which regions they are
located, what kind of projects they develop and if they have already developed projects
based on the new standard. / Com a entrada em vigor, em julho de 2013, da nova norma brasileira, NBR
15575:2013, passaram a ser exigidos nas novas construções de uso multifamiliar, níveis
mínimos de desempenho, tais como térmico, ilumínico, estrutural e acústico. Dessa
maneira, programas computacionais que simulam a transmissão sonora em edificações,
podem servir como ferramentas importantes aos profissionais, permitindo a verificação
do desempenho acústico virtual dos projetos, de forma rápida e econômica. Por serem
amplamente utilizados nos países europeus, possuem banco de dados dos elementos e
sistemas construtivos existentes na Europa. A partir disso, esse trabalho teve como
objetivo a avaliação de uma ferramenta computacional, de simulação da transmissão
sonora, para a realidade das construções brasileiras. Foram selecionadas 20 residências,
na cidade de Santa Maria - RS, para serem medidas in loco e depois simuladas, aos ruídos
aéreo e de impacto. As residências foram escolhidas, de acordo com padrão e sistemas
construtivos. Para maior representatividade das construções brasileiras, foram escolhidas
residências do padrão baixo, médio e alto. Os sistemas construtivos escolhidos foram
alvenaria estrutural, com paredes de bloco estrutural de concreto ou cerâmico; e concreto
armado, com paredes de tijolo vazado; todos com laje maciça de concreto. O programa
utilizado para as simulações foi o SONarchitect e todas as características, dos elementos
construtivos utilizados, foram inseridos no banco de dados do software. Foram obtidos
os valores de Ln,T , Dn,T,, e TR por banda de frequência, e seus valores ponderados de
Ln,T,w, Dn,T,w e TR médio, nas medições e simulações. Os valores ponderados medidos
e simulados foram similares, por outro lado os valores obtidos por banda de frequência
apresentaram divergência em relação às frequências mais baixas, precisamente de 50 Hz
a 100 Hz. Verificou-se também uma relação da perda de transmissão sonora ao ruído de
impacto com o tamanho da área da partição, na qual ocorre um aumento significativo no
isolamento sonoro em partições com áreas maiores. Além disso, foram determinados
coeficientes e fatores de segurança, para cada padrão e sistema construtivo, a serem
aplicados nos espectros das simulações. Com o objetivo de aproximar os valores simulados
dos valores medidos. Paralelamente à avaliação da ferramenta computacional, foram
aplicados questionários com 150 profissionais que desenvolvem projetos acústicos no país.
Essa etapa tinha como objetivo principal descobrir quais ferramentas e métodos são
mais utilizados pelos profissionais no desenvolvimento desses projetos. A partir de 31
questionários respondidos, foi possível determinar que 20,88% dos profissionais utilizam
alguma ferramenta computacional para desenvolver os projetos. Também foi possível
descobrir algumas características desses profissionais como curso e ano de formação, quais
as regiões que estão inseridos, que tipo de projetos desenvolvem e se já desenvolveram
projetos baseados na nova norma.
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Physics-based TCAD device simulations and measurements of GaN HEMT technology for RF power amplifier applications / Simulations physiques et mesures du composant de technologie GaN HEMT pour les applications d'amplificateur de puissance RFSubramani, Nandha kumar 16 November 2017 (has links)
Depuis plusieurs années, la technologie de transistors à effet de champ à haute mobilité (HEMT) sur Nitrure de Gallium (GaN) a démontré un potentiel très important pour la montée en puissance et en fréquence des dispositifs. Malheureusement, la présence des effets parasites dégrade les performances dynamiques des composants ainsi que leur fiabilité à long-terme. En outre, l'origine de ces pièges et leur emplacement physique restent incertains jusqu'à aujourd'hui. Une partie du travail de recherche menée dans cette thèse est axée sur la caractérisation des pièges existant dans les dispositifs HEMTs GaN à partir de mesures de paramètre S basse fréquence (BF), les mesures du bruit BF et les mesures I(V) impulsionnelles. Parallèlement, nous avons effectué des simulations physiques basées sur TCAD afin d'identifier la localisation des pièges dans le transistor. De plus, notre étude expérimentale de caractérisation et de simulation montre que les mesures BF pourraient constituer un outil efficace pour caractériser les pièges existant dans le buffer GaN, alors que la caractérisation de Gate-lag pourrait être plus utile pour identifier les pièges de barrière des dispositifs GaN HEMT. La deuxième partie de ce travail de recherche est axée sur la caractérisation des dispositifs AlN/GaN HEMT sur substrat Si et SiC. Une méthode d’extraction simple et efficace de la résistance canal et de la résistance de contact a été mise au point en utilisant conjointement la simulation physique et les techniques de caractérisation. Le principe de l’extraction de la résistance canal est basée sur la mesure de la résistance RON. Celle-ci est calculée à partir des mesures de courant de drain IDS et de la tension VDS pour différentes valeurs de températures En outre, nous avons procédé à une évaluation complète du comportement thermique de ces composants en utilisant conjointement les mesures et les simulations thermiques tridimensionnelles (3D) sur TCAD. La résistance thermique (RTH) a été extraite pour les transistors de différentes géométries à l'aide des mesures et ensuite validée par les simulations thermiques sur TCAD. / GaN High Electron Mobility Transistors (HEMTs) have demonstrated their capabilities to be an excellent candidate for high power microwave and mm-wave applications. However, the presence of traps in the device structure significantly degrades the device performance and also detriments the device reliability. Moreover, the origin of these traps and their physical location remains unclear till today. A part of the research work carried out in this thesis is focused on characterizing the traps existing in the GaN/AlGaN/GaN HEMT devices using LF S-parameter measurements, LF noise measurements and drain-lag characterization. Furthermore, we have used TCAD-based physical device simulations in order to identify the physically confirm the location of traps in the device. Moreover, our experimental characterization and simulation study suggest that LF measurements could be an effective tool for characterizing the traps existing in the GaN buffer whereas gate-lag characterization could be more useful to characterize the AlGaN barrier traps of GaN HEMT devices. The second aspect of this research work is focused on characterizing the AlN/GaN/AlGaN HEMT devices grown on Si and SiC substrate. We attempt to characterize the temperature-dependent on-resistance (RON) extraction of these devices using on-wafer measurements and TCAD-based physical simulations. Furthermore, we have proposed a simplified methodology to extract the temperature and bias-dependent channel sheet resistance (Rsh) and parasitic series contact resistance (Rse) of AlN/GaN HEMT devices. Further, we have made a comprehensive evaluation of thermal behavior of these devices using on-wafer measurements and TCAD-based three-dimensional (3D) thermal simulations. The thermal resistance (RTH) has been extracted for various geometries of the device using measurements and validated using TCAD-thermal simulations.
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Hluk rovinných desek / Flat Plates NoiseZlámal, Josef January 2018 (has links)
The master thesis summaries the findings results of a study focused on the spread of noise vibrating flat plates. Part of this thesis is measurements of flat plate noise in the anechoic chamber and finally their processing and evaluation. The next part of the thesis is focused on FEM acoustic simulation and comparing results with measurements.
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Array-Based Characterization of Military Jet Aircraft NoiseKrueger, David William 20 July 2012 (has links) (PDF)
Since the 1950s the jet aeroacoustics community has been involved in predicting and measuring the noise distribution in jets. In this work, cylindrical and planar Fourier near-field acoustical holography are used to investigate radiation from a full-scale, installed jet engine. Practical problems involving measurement aperture and the highly directional nature of the source are addressed. Insights from numerical simulations reveal usable reconstruction regions. A comparison of cylindrical and planar NAH for the respective measurement apertures shows cylindrical NAH outperforms planar NAH on reconstructions both towards and away from the source.
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SNIŽOVÁNÍ HODNOTY STAVENIŠTNÍHO HLUKU POMOCÍ MODELOVÁNÍ VÝROBNÍHO PROSTORU STAVBY A ÚPRAV TECHNOLOGICKÝCH POSTUPŮ PŘI VÝSTAVBĚ / REDUCING THE VALUE OF CONSTRUCTION NOISE BY MODELING THE PRODUCTION AREA OF CONSTRUCTION SITE AND BY ADJUSTING THE TECHNOLOGICAL PROCEDURES DURING CONSTRUCTIONKantová, Radka Unknown Date (has links)
This doctoral thesis focuses on noise generated during construction. It defines the legislative and physical aspects of this topic. It determines heavy machinery as noise source and categorizes them by their usage in construction technologies. It collects source data of the machinery noises which can be further used in prognostic models. It analyses the level of construction noise which can impact the nearby residential areas and offers methodology for modelling and designing the possible arrangements for the noise reduction. It defines partial effects of the construction site which are significant for the noise spreading. It establishes their role in the value of acoustic pressure level of the noise affecting the façade of the considered building. With the data collection and with case study verification it offers a prepared work tool which can be easily used to predict noise levels on construction sites and can be applied in the early constructions preparations. The structure of this thesis is planned for possible usage as university textbook or study support.
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