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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.
21

A Wide Band Adaptive All Digital Phase Locked Loop With Self Jitter Measurement And Calibration

Jiang, Bo 01 January 2016 (has links)
The expanding growth of mobile products and services has led to various wireless communication standards that employ different spectrum bands and protocols to provide data, voice or video communication services. Software deffned radio and cognitive radio are emerging techniques that can dynamically integrate various standards to provide seamless global coverage, including global roaming across geographical regions, and interfacing with different wireless networks. In software deffned radio and cognitive radio, one of the most critical RF blocks that need to exhibit frequency agility is the phase lock loop (PLL) frequency synthesizer. In order to access various standards, the frequency synthesizer needs to have wide frequency tuning range, fast tuning speed, and low phase noise and frequency spur. The traditional analog charge pump frequency synthesizer circuit design is becoming diffcult due to the continuous down-scalings of transistor feature size and power supply voltage. The goal of this project was to develop an all digital phase locked loop (ADPLL) as the alternative solution technique in RF transceivers by taking advantage of digital circuitry's characteristic features of good scalability, robustness against process variation and high noise margin. The targeted frequency bands for our ADPLL design included 880MHz-960MHz, 1.92GHz-2.17GHz, 2.3GHz-2.7GHz, 3.3GHz-3.8GHz and 5.15GHz-5.85GHz that are used by wireless communication standards such as GSM, UMTS, bluetooth, WiMAX and Wi-Fi etc. This project started with the system level model development for characterizing ADPLL phase noise, fractional spur and locking speed. Then an on-chip jitter detector and parameter adapter was designed for ADPLL to perform self-tuning and self-calibration to accomplish high frequency purity and fast frequency locking in each frequency band. A novel wide band DCO is presented for multi-band wireless application. The proposed wide band adaptive ADPLL was implemented in the IBM 0.13µm CMOS technology. The phase noise performance, the frequency locking speed as well as the tuning range of the digitally controlled oscillator was assessed and agrees well with the theoretical analysis.
22

[en] MODELS FOR ASSESSING THE SPREAD OF BRAZILIAN BROADBAND / [pt] MODELOS PARA A AVALIAÇÃO DA DISSEMINAÇÃO DE BANDA LARGA NO BRASIL

VITOR BRIL 26 August 2011 (has links)
[pt] Esta dissertação tem como objetivo a utilização de modelos de regressão linear para a taxa de penetração de banda larga, baseados nas variáveis desemprego, PIB per capita, grau de competividade do mercado e diversidade tecnológica, utilizando uma análise dos modelos em diferentes países, com ênfase no Brasil, onde, nos últimos anos, tem sido analisadas diferentes alternativas para alcançar os objetivos do Plano Nacional de Banda Larga. A aplicação da metodologia apresentará a relação destas variáveis para os países com índices de adoção de banda larga ainda baixos, onde o Brasil está incluído, mas também apresenta a análise para países mais maduros neste índice. Estas análises poderão auxiliar na tomada de decisão das políticas públicas adequadas para o Brasil, buscando a aproximação dos países desenvolvidos neste setor. / [en] This thesis has as objective the developing of a model to estimate the broadband density penetration based on the unemployment rate, Gross Domestic Product per capita, market share and technological diversity. In addition of a global analysis, the thesis is focused in the Brazilian scenario, which is in a process of decision in which government policies to achieve the results expected by the National Broadband Plan. The methodoly will present the relation between these variables for the countries with lower broadband indexes, where Brazil is included, and the analysis for the countries with better indexes. These analyses can help Brazilian government in which policies should help Brazil to achieve results closer than the more mature countries in this sector.
23

Ultra Wide Band Sigma-Delta modulator in CMOS090 / UWB Sigma-Delta modulator i CMOS090

Jonsson, Fredrik January 2004 (has links)
<p>Today the frequency spectrum is full of wireless standards. The most common technique being used is the frequency modulation. To take advantage of this and the technology improvement a new wireless communication standard is being developed. This standard is using a low power impulse modulation method, allowing it to overlap with other standards. The proposed standard called IEEE802.15.3a is applied at an Ultra Wide Band and has potential to be used both in interchip and intrasystem communication, since it allows a very high data density. </p><p>In this thesis the analog to digital converter is designed, which is one part of a communication system. Although the signal bandwidth is very wide the converter is designed as a Sigma-Delta modulator, which is most suitable for low-speed applications. Its main advantages over high-speed converters are less area and less power consumption. The goal of this project is to investigate if the CMOS090 process technology will be sufficient for reaching a signal-to-noise ratio, SNR, of 30 dB in a signal band of 264 MHz. </p><p>The main limiting factor during the design of the modulator is the excess feedback delay. This delay degrades the SNR and can even make the system unstable. At a feedback delay of 83 ps and a sampling frequency of 6.336 GHz, the maximum SNR achieved was 27 dB. At this high frequency the modulator is close to instability. Hence, to ensure stability a maximum sampling frequency of 4.224 GHz is chosen, achieving a SNR of 19 dB. </p><p>The effect of the feedback delay can be reduced either by using a different structure or by using compensation methods, either of them would probably allow a SNR above 30 dB.</p>
24

UWB Antennas for Wall Penetrating Radar Systems

Javashvili, Otar January 2009 (has links)
<p>Basic properties and new design principles of ultra wideband Vivaldi antennas are presentedand discussed in this paper. The focus will be on the modeling of Vivaldi antenna design curves, by which it is constructed; its simulation results, realization and the measurements.</p><p>According to the aim of this research the discussion starts with the review of the previous researches done for Vivaldi antennas. Introductory part of the report also contains the problem description for the current project and the classification of the goals to be achieved. As a theoretical review, the discussion initiates with the definitions anddescription of basic parameters of the antennas and covers a short presentation of UWBpulse-based radar system. The attention will be focused on UWB signals behavior and characterization, their propagation principles and basic troubles stands nowadays. As anapplication the wall penetrating Radar systems will be considered. The major part of thereport holds on the investigation of the design principles of Vivaldi Antenna andoptimization of the key parameters for achieving the best performance for radar. Theending part of the report shows the simulations and measurement results and theircomparisons following with conclusions/discussions.</p><p>The report will be supportive for the antenna designers, who work for UWB systems andparticularly for Vivaldi antennas, as long as there are showing up detailed descriptions ofVivaldi antenna characteristics depending on its shape and substrate properties. The modelfor designing Vivaldi antennas, given in this project, can successfully be applied for almostall the cases used in practice nowadays.</p>
25

UWB Antennas for Wall Penetrating Radar Systems

Javashvili, Otar January 2009 (has links)
Basic properties and new design principles of ultra wideband Vivaldi antennas are presentedand discussed in this paper. The focus will be on the modeling of Vivaldi antenna design curves, by which it is constructed; its simulation results, realization and the measurements. According to the aim of this research the discussion starts with the review of the previous researches done for Vivaldi antennas. Introductory part of the report also contains the problem description for the current project and the classification of the goals to be achieved. As a theoretical review, the discussion initiates with the definitions anddescription of basic parameters of the antennas and covers a short presentation of UWBpulse-based radar system. The attention will be focused on UWB signals behavior and characterization, their propagation principles and basic troubles stands nowadays. As anapplication the wall penetrating Radar systems will be considered. The major part of thereport holds on the investigation of the design principles of Vivaldi Antenna andoptimization of the key parameters for achieving the best performance for radar. Theending part of the report shows the simulations and measurement results and theircomparisons following with conclusions/discussions. The report will be supportive for the antenna designers, who work for UWB systems andparticularly for Vivaldi antennas, as long as there are showing up detailed descriptions ofVivaldi antenna characteristics depending on its shape and substrate properties. The modelfor designing Vivaldi antennas, given in this project, can successfully be applied for almostall the cases used in practice nowadays.
26

Ultra Wide Band Sigma-Delta modulator in CMOS090 / UWB Sigma-Delta modulator i CMOS090

Jonsson, Fredrik January 2004 (has links)
Today the frequency spectrum is full of wireless standards. The most common technique being used is the frequency modulation. To take advantage of this and the technology improvement a new wireless communication standard is being developed. This standard is using a low power impulse modulation method, allowing it to overlap with other standards. The proposed standard called IEEE802.15.3a is applied at an Ultra Wide Band and has potential to be used both in interchip and intrasystem communication, since it allows a very high data density. In this thesis the analog to digital converter is designed, which is one part of a communication system. Although the signal bandwidth is very wide the converter is designed as a Sigma-Delta modulator, which is most suitable for low-speed applications. Its main advantages over high-speed converters are less area and less power consumption. The goal of this project is to investigate if the CMOS090 process technology will be sufficient for reaching a signal-to-noise ratio, SNR, of 30 dB in a signal band of 264 MHz. The main limiting factor during the design of the modulator is the excess feedback delay. This delay degrades the SNR and can even make the system unstable. At a feedback delay of 83 ps and a sampling frequency of 6.336 GHz, the maximum SNR achieved was 27 dB. At this high frequency the modulator is close to instability. Hence, to ensure stability a maximum sampling frequency of 4.224 GHz is chosen, achieving a SNR of 19 dB. The effect of the feedback delay can be reduced either by using a different structure or by using compensation methods, either of them would probably allow a SNR above 30 dB.
27

Study of Stepped Impedance Resonator on Microwave Filter Components

Chang, Yu-Chi 24 June 2011 (has links)
This dissertation divides into three parts: (a) design and research of asymmetric stepped impedance resonator (SIR); (b) design and fabrication of dual-band and ultra-wide band (UWB) bandpass filters (BPFs) and (c) design and fabrication of millimeter wave filters. (a)design and research of asymmetric stepped impedance resonator. In the first part of the dissertation, we propose an asymmetric SIR, and the effect of electrical length ratio and impedance ratio on the performance of frequency has been discussed in detail. The insertion loss and spurious can be controlled by the structural parameters of asymmetric SIR which decreases the length of resonator effectively and achieves the reduction of whole size. Additionally, this characterization of the asymmetric SIR can be extensively applied on the interconnection of RFIC. (b) design and fabrication of dual-band and ultra-wide band (UWB) filters. In the second part of the dissertation, we propose dual-band and UWB BPFs by using asymmetric SIRs. The designed dual-band BPF is conformed to the standard of wireless local area network (WLAN), and the designed UWB BPF is conformed to the standard that Federal Communications Commission (FCC) defined. The structural parameters of asymmetric SIR can be adjusted accurately by the theoretical equations we calculated. Then, the ideal performance can be achieved. (c) design and fabrication of millimeter wave filters. In the third part of the dissertation, we propose the design of millimeter wave filters fabricated by the standard of complementary metal-oxide semiconductor (CMOS). Asymmetric SIRs are used to design the microwave filter to estimate that the feasibility of system on chip (SoC). Finally, some suggestions are made in the future work on technology for system on chip (SoC).
28

Photonics Ultra-Wide-Band Doublet Pulse Based on Tapered Directional Coupler Integrated Electroabsorption Modulator

Kuo, Yu-zheng 15 July 2011 (has links)
Ultra Wide Band (UWB) is a short-pulse signal which has extremely potential in wireless communication system due to the advantages of high data rate, better immunity to multipath fading, wide bandwidth, and high capability. According to the Federal Communications Commission (F.C.C.), UWB only can be transmitted in short distance of a few to tens of meters due to low power density (-41.3dBm/MHz). However, optical fiber has low loss and cost and wide bandwidth, so it can be achieved in wide area network. In this work, we propose a novel method to generate optical UWB doublet pulse without complicated setup. When electroabsorption modulator (EAM) integrating a taper optical directional coupler (TODC) was applied field, the transmission loss and coupling would change resulting from the absorption coefficient and effective index of active waveguide with the applied field. So, we used a single mode fiber collecting the power after the device, we could get the valley shape transfer function. Using the transfer function of electro-absorption modulator (EAM) integrating TODC we inject a Gaussian pulse into the EAM in the range of valley shape, and it can transform an electrical pulse into optical UWB doublet pulse by acceptable operating point. Therefore, the optical signals could be transmitted in optical fiber so that it can reduce loss of the electro-optic transformation. Experimentally, the full wave at half maximum of doublet pulse, 10dB bandwidth, fractional bandwidth were 75ps, 7.5GHz, 125%, respectively, and power density was less than -41.3dBm/MHz. These were all meeting the F.C.C. standard. In the future, we will use long distant optical fiber to transmitted UWB signal, and compare with different distance. Finally, we will check the UWB signal can be transmitted in optical fiber to achieve wide range signal transmission by bit error rate test.
29

Optimization through Co-Simulation of Antenna, Bandpass Filter and Low-Noise Amplifier at 6-9 GHz

Khan, Abbas January 2012 (has links)
Ultra-wide band (UWB) 6-9 GHz antenna, band pass filter and low-noise amplifier (LNA) optimization using co-simulation of the RF front-end. At higher frequencies, carefully conducted design methodologies are required for RF front-end parameter optimization, such as power gain and low noise figure with low power consumption.
30

Onduleur à forte intégration utilisant des semi-conducteurs à grand gap / High density inverter using wide band gap switches

Regnat, Guillaume 11 July 2016 (has links)
Les composants semi-conducteurs à base de matériaux à grand gap (SiC et GaN) présentent des caractéristiques intéressantes pour la réalisation de convertisseurs d’électronique de puissance toujours plus intégrés. Cependant, le packaging des composants traditionnels en silicium ne semble plus adapté pour ces nouveaux composants et apparaît même comme un facteur limitant. Le développement d’un packaging adapté aux caractéristiques des composants à grand gap est alors nécessaire. Les travaux développés dans cette thèse proposent un nouveau packaging tridimensionnel basé sur un procédé de fabrication de circuit imprimé. L’architecture du module est basé sur le concept « Power Chip On Chip » dont le principe de base permet de réduire les perturbations électromagnétiques. Le procédé de fabrication des circuits imprimés offre une grande flexibilité pour le routage en trois dimensions et permet de s’affranchir de l’interconnexion par fil de bonding entre le package et la puce. La démarche de conception du module s’appuie sur une approche multi-physique afin de qualifier le comportement électromagnétique et thermique du module puis de proposer des voies d’optimisation. Un prototype d’un module implémentant quatre cellules de commutation en parallèle, à base de MOSFET SiC, a été produit avec des moyens de production industriels. Les différents tests réalisés valident l’approche retenue dans ce projet mais soulignent également les aspects technologiques à approfondir pour la réalisation d’un module de puissance industriel. / Wide-band-gap (WBG) semiconductors (SiC and Gan) offer interesting characteristics to realize high density power electronics converters. Conventional packaging used for silicon devices is no more adapted for those now components. Development of dedicated packaging for WBG devices is absolutely required. This PhD thesis presents a new 3D package based on Printed Circuit Board (PCB) industrial process. The module architecture is based on “Power Chip On Chip” concept which allows reducing electromagnetic perturbations. PCB fabrication process offers high design flexibility in three dimensions and allows removing wire bonding to interconnect power die and package. The power module design process is buit on multi-physics design tools in the aim to quantify electromagnetic and thermal behavior of the module. Furthermore, several optimization parameters are highlighted. A power module prototype, with four commutation cells in parallel based on SiC MOSFET, has been produced thanks to industrial facilities. Tests realized on new power module confirm the validity of the concept but furthermore to highlight critical technological parameters to realize an industrial power module.

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