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.

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.

The waveform of a radar signal affects the resolution in velocity and distance. The ambiguity function is used as an aid for analysing narrow band radar signals simultaneously in time and frequency. An analysing tool for wide band radar signals is missing. This thesis describes a generalised ambiguity function to be utilised for study of wide band signals. Waveforms are further synthesised with help of the developed analysing tool. The aim is to start with a certain ambiguity function and find a waveform that reproduces the same ambiguity function. Mathematical formulas are presented and implemented in Matlab to produce the wide band ambiguity function. Functions for developing waveforms by synthesis is also implemented. It turns out that the Hermitian functions used as base functions do not preserve the orthogonality when implemented as wide band signals. The synthesis is not fully successful. Therefore an alternative method with numerical optimisation is used in an attempt to find an optimal waveform.

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).

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.

No description available.

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.

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.

No description available.

Ce mémoire présente une méthodologie de conception d’antennes Ultra Large Bande volumiques à ondes progressives, d’encombrement réduit, dédiées au rayonnement d’impulsions ultra-courtes dans une bande de fréquence allant de 300 MHz à 3 GHz. L’objectif est de concilier une large bande de fréquences rayonnées et de bonnes performances de rayonnements transitoires (niveau élevé, signaux brefs) tout en limitant l’encombrement des antennes. L’insertion d’un matériau diélectrique a été associée au design des antennes ULB afin de réduire leurs dimensions. Ceci a conduit à la synthèse et à la caractérisation de matériaux diélectriques innovants à base de géopolymères, dont la maîtrise de la valeur de la permittivité est possible. Un prototype d’antenne a été réalisé, des mesures des différentes caractéristiques de rayonnement ont été effectuées et comparées aux résultats de simulation pour s’assurer du bon fonctionnement de celle-ci. Cette antenne a également été associée à des applications radar pour la détection de cibles se situant dans différents milieux (air et sol). Les réponses impulsionnelles obtenues pour les différentes scènes radar testées ont été comparées aux résultats mesurées avec d’autres antennes connues. / This thesis presents the design of small form factor Ultra Wide Band antennas with progressive waves shape, which is dedicated to ultra-short pulses radiation in a frequency band ranging from 300MHz to 3GHz. The aim is to combine a wide band of radiated frequencies and good performance while limiting the size of antennas. The insertion of a dielectric material has been associated with the design of Ultra Wide Band antennas to reduce their dimensions. This has led to the synthesis and characterization of innovative dielectric materials based on geopolymers, whose mastering of the value of the permittivity is possible. An antenna prototype has been manufactured and measurements of the different radiation characteristics were made and compared to the simulation results to ensure its good functioning. This antenna has also been associated with radar applications for the detection of targets in different environments (air and soil). The impulse responses obtained for the different tested radar scenes have been compared with the results obtained with other known antennas.