• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 13
  • 4
  • 2
  • 1
  • Tagged with
  • 24
  • 24
  • 8
  • 7
  • 5
  • 5
  • 5
  • 4
  • 4
  • 4
  • 4
  • 3
  • 3
  • 3
  • 3
  • 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.
21

Conception, réalisation et caractérisation d'inductances et de transformateurs tridimensionnels pour applications RF et microondes / Design, realization and characterization of three-dimensional inductors and transformers for RF (radio frequency) and microwave applications

Bushueva, Olga 07 October 2016 (has links)
La miniaturisation, la fabrication et l'intégration des composants passifs RF constituent des enjeux majeurs actuels, sans oublier le critère du coût de fabrication, très important notamment pour les applications grand public. Les composants passifs tels que les inductances et les transformateurs font l'objet d'un effort de développement permanent pour accroitre leurs performances et réduire la surface occupée. Les travaux décrits dans ce manuscrit s'inscrivent dans ce contexte et visent le développement d'une nouvelle filière technologique permettant la réalisation à faible coût de composants inductifs tridimensionnels à hautes performances. Le travail présenté dans ce mémoire s'articule en quatre chapitres. Le premier chapitre dresse un état de l'art des inductances et des transformateurs intégrés en abordant les principales topologies utilisées, les technologies de fabrication et les applications. Dans le deuxième chapitre, l'étude et l'optimisation des inductances et des transformateurs solénoïdaux est abordée après avoir décrit les origines des pertes limitant les performances. Pour cela, nous avons recours à la simulation électromagnétiques 3D. Dans le troisième chapitre, un problème de caractérisation des composants inductifs à forts coefficients de surtension est soulevé. Après avoir constaté que l'environnement de mesure réduisait artificiellement les performances, quelques solutions sont proposées et vérifiées expérimentalement. Enfin, le dernier chapitre traite de la fabrication et de la caractérisation des composants mis au point. Les meilleures performances mesurées correspondent à un facteur de qualité de 61 à 5,4 GHz pour une inductance de 2,5 nH et un gain maximum disponible de -0,5 dB à -0,39 dB sur la plage 3,8 - 6,5 GHz pour un transformateur 2:2. Ces résultats placent ces composants parmi les meilleures réalisations actuelles. / The miniaturization, fabrication and integration of RF passive components are current major challenges, also taking into account the fabrication cost which is very important especially for consumer applications. Passive components such as inductors and transformers are subject to an ongoing development to improve their performance and reduce the area occupied. The work described in this manuscript is part of that context and target the development of a new technological process allowing the production of low-cost three-dimensional high-performance inductive components. The work presented in this paper is divided into four chapters. The first chapter describes the state of the art of integrated inductors and transformers by addressing the main topologies used fabrication technologies and applications. In the second chapter, the study and optimization of solenoid inductors and transformers is discussed after describing the origins of performance limiting losses. For this, we use the 3D electromagnetic simulation. In the third chapter, the problem concerning the characterization of inductive components with high Q factor is raised. After finding that the measurement environment artificially reduces performance, some solutions are proposed and experimentally verified. Finally, the last chapter discusses the fabrication and characterization of developed components. The best measured performance corresponds to a quality factor of 61 to 5.4 GHz for an inductance value of 2.5 nH and a maximum available gain of -0.5 dB to 0.39 dB over the range from 3.8 to 6.5 GHz for a 2:2 transformer. These results place these components among the best current achievements.
22

Design and Analysis of High-Q, Amorphous Microring Resonator Sensors for Gaseous and Biological Species Detection

Manoharan, Krishna 27 April 2009 (has links)
No description available.
23

Compact Superconducting Dual-Log Spiral Resonator with High Q-Factor and Low Power Dependence.

Excell, Peter S., Hejazi, Z.M. January 2002 (has links)
No / A new dual-log spiral geometry is proposed for microstrip resonators, offering substantial advantages in performance and size reduction at subgigahertz frequencies when realized in superconducting materials. The spiral is logarithmic in line spacing and width such that the width of the spiral line increases smoothly with the increase of the current density, reaching its maximum where the current density is maximum (in its center for ¿/2 resonators). Preliminary results of such a logarithmic ten-turn (2 × 5 turns) spiral, realized with double-sided YBCO thin film, showed a Q.-factor seven times higher than that of a single ten-turn uniform spiral made of YBCO thin film and 64 times higher than a copper counterpart. The insertion loss of the YBCO dual log-spiral has a high degree of independence of the input power in comparison with a uniform Archimedian spiral, increasing by only 2.5% for a 30-dBm increase of the input power, compared with nearly 31% for the uniform spiral. A simple approximate method, developed for prediction of the resonant frequency of the new resonators, shows a good agreement with the test results.
24

Interface circuits for readout and control of a micro-hemispherical resonating gyroscope

Mayberry, Curtis Lee 12 January 2015 (has links)
Gyroscopes are inertial sensors that measure the rate or angle of rotation. One of the most promising technologies for reaching a high-performance MEMS gyroscope has been development of the micro-hemispherical shell resonator. (μHSR) This thesis presents the electronic control and read-out interface that has been developed to turn the μHSR into a fully functional micro-hemispherical resonating gyroscope (μHRG) capable of measuring the rate of rotation. First, the μHSR was characterized, which both enabled the design of the interface and led to new insights into the linearity and feed-through characteristics of the μHSR. Then a detailed analysis of the rate mode interface including calculations and simulations was performed. This interface was then implemented on custom printed circuit boards for both the analog front-end and analog back-end, along with a custom on-board vacuum chamber and chassis to house the μHSR and interface electronics. Finally the performance of the rate mode gyroscope interface was characterized, showing a linear scale factor of 8.57 mv/deg/s, an angle random walk (ARW) of 34 deg/sqrt(hr) and a bias instability of 330 deg/hr.

Page generated in 0.0298 seconds