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  • 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

Contribution au développement du transistor bipolaire à fort gain et d'un interrupteur bidirectionnel à quatre quadrants / The contribution to the development of the super-gain BJT and of a four-quadrants bidirectional switch

Ren, Zheng 01 June 2018 (has links)
Afin de répondre aux besoins en management efficace de l’énergie électrique dans les bâtiments intelligents, le laboratoire GREMAN a proposé une nouvelle topologie d’interrupteur bidirectionnel de 600 V nommé TBBS. Les études antérieures ont validé la bidirectionnalité en courant et en tension de cette nouvelle topologie. Les travaux de recherche menées dans cette thèse avaient pour l’objectif d’approfondir, de compléter nos connaissances sur ce nouvel interrupteur bidirectionnel ainsi que sur le transistor bipolaire à fort gain. Le premier chapitre introduit le fonctionnement principal du TBBS et sa modélisation physique sous un environnement de simulation à éléments finis. Le deuxième chapitre présente le travail concernant la caractérisation expérimentale du TBBS et du transistor bipolaire à fort gain sous température contrôlée. Enfin la modélisation électrique du TBBS et du transistor bipolaire à fort gain est présentée dans le troisième et dernier chapitre. / In order to meet the requirement of more efficient electrical energy management for intelligent buildings, a new 600V bidirectional switch, named as TBBS, has been proposed by the GREMAN laboratory. Previous studies have validated the current and voltage bidirectionality of this newly proposed topology. The research work carried out in this thesis deals with a deeper and more comprehensive study of this bidirectional switch and its elementary component - the High-gain bipolar juncion transistor. The first chapter introduces the operation of the TBBS and its physical modeling in a finite element simulation environment. The second chapter presentes the research work related to the experimental caracterisation of the TBBS and the High-gain bipolar junction transistor. At last the third chapter deals with the electrical modeling of these two bipolar components.
2

SiC Readout IC for High Temperature Seismic Sensor System

Tian, Ye January 2017 (has links)
Over the last decade, electronics operating at high temperatures have been increasingly demanded to support in situ sensing applications such as automotive, deep-well drilling and aerospace. However, few of these applications have requirements above 460 °C, as the surface temperature of Venus, which is a specific target for the seismic sensing application in this thesis. Due to its wide bandgap, Silicon Carbide (SiC) is a promising candidate to implement integrated circuits (ICs) operating in such extreme environments. In this thesis, various analog and mixed-signal ICs in 4H-SiC bipolar technology for high-temperature sensing applications are explored, in which the device performance variation over temperatures are considered. For this purpose, device modeling, circuit design, layout design, and device/circuit characterization are involved. In this thesis, the circuits are fabricated in two batches using similar technologies. In Batch 1, the first SiC sigma-delta modulator is demonstrated to operate up to 500 °C with a 30 dB peak SNDR. Its building blocks including a fully-differential amplifier, an integrator and a comparator are characterized individually to investigate the modulator performance variation over temperatures. In the succeeding Batch 2, a SiC electromechanical sigma-delta modulator is designed with a chosen Si capacitive sensor for seismic sensing on Venus. Its building blocks including a charge amplifier, a multiplier and an oscillator are designed. Compared to Batch 1, a smaller transistor and two metal-interconnects are used to implement higher integration ICs in Batch 2. Moreover, the first VBIC-based compact model featured with continuous-temperature scalability from 27 to 500 °C is developed based on the SiC transistor in Batch 1, in order to optimize the design of circuits in Batch 2. The demonstrated performance of ICs in Batch 1 show the feasibility to further develop the SiC readout ICs for seismic sensor system operating on Venus. / <p>QC 20170911</p>
3

Modelling the temperature dependences of Silicon Carbide BJTs

Fernández S., Alejandro D. January 2016 (has links)
Silicon Carbide (SiC), owing to its large bandgap, has proved itself to be a very viable semiconductor material for the development of extreme temperature electronics. Moreover, its electrical properties like critical field (Ecrit) and saturation velocity (vsat) are superior as compared to the commercially abundant Silicon, thus making it a better alternative for RF and high power applications. The in-house SiC BJT process at KTH has matured a lot over the years and recently developed devices and circuits have shown to work at temperatures exceeding 500˚C. However, the functional reliability of more complex circuits requires the use of simulators and device models to describe the behavior of constituent devices. SPICE Gummel Poon (SGP) is one such model that describes the behavior of the BJT devices. It is simpler as compared to the other models because of its relatively small number of parameters. A simple semi-empirical DC compact model has been successfully developed for low voltage applications SiC BJTs. The model is based on a temperature dependent SiC-SGP model. Studies over the temperature dependences for the SGP parameters have been performed. The SGP parameters have been extracted and some have been optimized over a wide temperature range and they have been compared with the measured data. The accuracy of the developed compact model based on these parameters has been proven by comparing it with the measured data as well. A fairly accurate performance at the required working conditions and correlation with the measured results of the SiC compact model has been achieved.
4

High-Temperature Analog and Mixed-Signal Integrated Circuits in Bipolar Silicon Carbide Technology

Hedayati, Raheleh January 2017 (has links)
Silicon carbide (SiC) integrated circuits (ICs) can enable the emergence of robust and reliable systems, including data acquisition and on-site control for extreme environments with high temperature and high radiation such as deep earth drilling, space and aviation, electric and hybrid vehicles, and combustion engines. In particular, SiC ICs provide significant benefit by reducing power dissipation and leakage current at temperatures above 300 °C compared to the Si counterpart. In fact, Si-based ICs have a limited maximum operating temperature which is around 300 °C for silicon on insulator (SOI). Owing to its superior material properties such as wide bandgap, three times larger than Silicon, and low intrinsic carrier concentration, SiC is an excellent candidate for high-temperature applications. In this thesis, analog and mixed-signal circuits have been implemented using SiC bipolar technology, including bandgap references, amplifiers, a master-slave comparator, an 8-bit R-2R ladder-based digital-to-analog converter (DAC), a 4-bit flash analog-to-digital converter (ADC), and a 10-bit successive-approximation-register (SAR) ADC. Spice models were developed at binned temperature points from room temperature to 500 °C, to simulate and predict the circuits’ behavior with temperature variation. The high-temperature performance of the fabricated chips has been investigated and verified over a wide temperature range from 25 °C to 500 °C. A stable gain of 39 dB was measured in the temperature range from 25 °C up to 500 °C for the inverting operational amplifier with ideal closed-loop gain of 40 dB. Although the circuit design in an immature SiC bipolar technology is challenging due to the low current gain of the transistors and lack of complete AC models, various circuit techniques have been applied to mitigate these problems. This thesis details the challenges faced and methods employed for device modeling, integrated circuit design, layout implementation and finally performance verification using on-wafer characterization of the fabricated SiC ICs over a wide temperature range. / <p>QC 20170905</p>

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