Depuis plusieurs années, le domaine des télécommunications et des nouvelles technologies connaît un véritable essor. On assiste aujourd'hui à un engouement sans précédent du grand public pour les applications de communication multimédia (données, voix, photos, vidéos) et la demande est de plus en plus forte pour un transfert à haut débit entre des équipements communicants mobiles et à encombrement réduit. De plus, que le mode d'utilisation soit nomade ou sédentaire, les technologies radio sans fils (Bluetooth, WiFi, GPRS, UMTS, WiMax) connaissent un grand succès. Pour répondre à ces besoins croissants de communication sans fils à haut débit, les futures générations d'équipements vont faire appel à des antennes de plus en plus performantes. Celles-ci devront fonctionner sur plusieurs bandes de fréquences ou sur une large bande. Mais elles devront aussi, pour des raisons pratiques et esthétiques, être intégrées aux systèmes radio, ce qui requiert la mise au point de structures compactes, discrètes et n'ayant pas de problèmes de compatibilité électromagnétique avec les circuits électroniques environnants. Pour répondre à ces différents objectifs, nous avons axé notre recherche sur les antennes tridimensionnelles qui offrent un grand nombre de degrés de liberté. Mais ces structures sont souvent complexes car elles comportent de nombreux paramètres. Afin de mieux les appréhender, nous proposons dans cette thèse d'élaborer une démarche de conception de ces antennes. Ainsi, nous commençons par l'étude systématique d'une antenne canonique constituée d'un dipôle placé à proximité d'une cavité métallique rectangulaire. L'effet des différents paramètres est analysé afin de mettre en évidence l'importance relative de chacun d'entre eux et de proposer ainsi une démarche de conception pour optimiser la bande passante et le rayonnement de l'antenne. Dans un deuxième temps, nous présentons la conception d'une antenne tridimensionnelle compacte, large bande et directive, l'antenne "sonde en F et triangle", qui offre l'avantage de présenter un diagramme de rayonnement stable en fréquence. Puis, fort de l'expérience acquise sur l'antenne dipôle, nous procédons de nouveau à une étude de l'influence sur l'impédance des différents paramètres de cette antenne complexe. Celle-ci permet d'élaborer une méthodologie de conception simple, rapide, efficace et générale. Nous pouvons ainsi optimiser l'antenne "sonde en F et triangle" et atteindre une bande passante en adaptation comprise entre 3.1 et 6.1 GHz. Le diagramme de rayonnement de cette antenne est stable sur la bande passante et le gain moyen de cette antenne est de 6 dB. Une caractérisation dans le domaine temporel est ensuite proposée afin de connaître le comportement de l'antenne dans une communication UWB. Enfin, l'antenne "sonde en F et triangle" est mise en cavité afin d'étudier ses propriétés lors de l'intégration dans un système radio. Des analogies et différences entre cette antenne complexe et le système {dipôle et cavité} sont également mises en évidence.

For ultra-wideband (UWB) communications, acquisition is challenging. The reason is from the ultra short pulse shape and ultra dense multipath interference. Ultra short pulse indicates the acquisition region is very narrow. Sampling is another challenge for UWB design due to the need for ultra high speed analog-to digital converter.<p>A sub-optimum and under-sampling scheme using pilot codes as transmitted reference is proposed here for acquisition. The sampling rate for the receiver is at the symbol rate. A new architecture, the reference aided matched filter is studied in this project. The reference aided matched filter method avoids using complex rake receiver to estimate channel parameters and high sampling rate for interpolation. A limited number of matched filters are used as a filter bank to search for the strongest path. Timing offset for acquisition is then estimated and passed to an advanced verification algorithm. For optimum performance of acquisition, the adaptive post detection integration is proposed to solve the problem from dense inter-symbol interference during the acquisition. A low-complex early-late gate tracking loop is one element of the adaptive post detection integration. This tracking scheme assists in improving acquisition accuracy. The proposed scheme is evaluated using Matlab Simulink simulations in term of mean acquisition time, system performance and false alarm. Simulation results show proposed algorithm is very effective in ultra dense multipath channels. This research proves reference aided acquisition with tracking loop is promising in UWB application.

Depuis quelques années le nouveau paradigme d'internet des objets, qui se traduit par la connexion des objets de la vie quotidienne à internet grâce à des dispositifs électroniques intégrés, est devenu plus qu'un simple concept et a commencé à entrer dans la réalité. Il en est ainsi des systèmes d'identification par radiofréquence (RFID), qui font partie des technologies disponibles. Lorsque le coût et la taille des tags deviennent des exigences prépondérantes, l'adoption de tags (semi-)passifs fondés sur la modulation d'un signal rétrodiffusé représente une solution attractive. En outre, l'utilisation de techniques ULB apporte des avantages propres à favoriser le remplacement d'une partie des systèmes RFID actuels qui souffrent de certains défauts tels qu'une trop forte consommation ou une faible robustesse en présence d'interférence. La thèse de doctorat se place dans ce contexte: elle a pour objectif l'étude des systèmes ULB RFID semi-passifs et se situe dans le cadre du projet européen SELECT, qui vise à développer et à évaluer un tel système. La prise de conscience qu'il était fondamental de comprendre les mécanismes électromagnétiques intrinsèques à la communication lecteur-tag, préalablement à la conception du système, s'est traduite par la mise en oeuvre d'une collaboration franco-italienne dans le cadre d'une cotutelle de thèse. C'est donc au départ autour d'une analyse fine et d'une modélisation des aspects antennaires et du canal radio entre le lecteur et le tag que la 1re partie du travail s'est construite. La 2nde partie a exploité ces travaux pour l'élaboration des schémas de modulation et de codage du lecteur et du tag pour les systèmes semi-passifs.

For ultra-wideband (UWB) communications, acquisition is challenging. The reason is from the ultra short pulse shape and ultra dense multipath interference. Ultra short pulse indicates the acquisition region is very narrow. Sampling is another challenge for UWB design due to the need for ultra high speed analog-to digital converter.<p>A sub-optimum and under-sampling scheme using pilot codes as transmitted reference is proposed here for acquisition. The sampling rate for the receiver is at the symbol rate. A new architecture, the reference aided matched filter is studied in this project. The reference aided matched filter method avoids using complex rake receiver to estimate channel parameters and high sampling rate for interpolation. A limited number of matched filters are used as a filter bank to search for the strongest path. Timing offset for acquisition is then estimated and passed to an advanced verification algorithm. For optimum performance of acquisition, the adaptive post detection integration is proposed to solve the problem from dense inter-symbol interference during the acquisition. A low-complex early-late gate tracking loop is one element of the adaptive post detection integration. This tracking scheme assists in improving acquisition accuracy. The proposed scheme is evaluated using Matlab Simulink simulations in term of mean acquisition time, system performance and false alarm. Simulation results show proposed algorithm is very effective in ultra dense multipath channels. This research proves reference aided acquisition with tracking loop is promising in UWB application.

Ultra-wideband systems can be used in indoor wireless personal area network (WPAN) or short-range wireless local area network (WLAN) transmission. Yet owing to the effects of indoor dense multipath, it will cause more power consumption. We usually use Rake receiver to improve system performance. However, we should do some compromise between system performance and the design complexity. Thus, the concept of Selective Rake can be used to substitute for the conventional Rake receiver. Selective Rake receiver uses fewer but more powerful paths instead of using all the paths to raise system performance. Hence, we have to precisely detect the multipath components for best performance. Earlier we use CLEAN algorithm to estimate the multipath components. The CLEAN algorithm can be used in selecting the paths with relatively high energy. But as the impact of frequency selective fading makes the transmitted signal distorted, the CLEAN algorithm no longer applies to this situation. Thus, we use Multiscale CLEAN algorithm instead. Multiscale CLEAN algorithm calculate the value of cross-correlation between the received signal and a set of waveforms, and then choose the higher one as the waveform transmitted. Besides, we use Maximal Ratio Combining to weigh the different paths to get the signal with more power. We represent the signal affected by frequency selective fading by using the second derivatives of Gaussian waveform function with different effective widths of pulse. The waveforms corresponding different effective widths have different spectra which represent the different effects of fading. It is seen that that the multiscale CLEAN has better performance than the CLEAN algorithm with more precise estimation of multipath components. In simulation result, we can figure out path searching using Multiscale CLEAN algorithm is more accurate than using CLEAN algorithm. Even the path with smaller energy gain, using multiscale CLEAN algorithm can search successfully, while CLEAN algorithm cannot do.

The main contents of this thesis are improving a UWB LNA, and analyze the input-matching, the noise, and the gain. First we increase the width of the input transistor, and remove source-degeneration inductor. Those ways can increase the gain and reduce the noise of the circuit. In the input matching, we use a shunt capacitor, a series inductor, and the impedance of the transistor itself to achieve high frequency matching. The lower frequency matching is achieved by negative feedback resistor. The UWB LNA dissipates 10.14 mW power and achieves input return loss (S11) below -11.5 dB, output return loss (S22) below -11.9 dB, forward gain (S21) of 14.4¡Ó0.4 dB, reverse isolation (S12) below -26.7 dB, and noise figure (NF) of 2.6~3.5 dB over the 3.1~10.6 GHz band of interest. 1-dB compression point (P1dB) of -16.8 dBm and input third-order inter-modulation point (IIP3) of -8.1 dBm are achieved at 6.85 GHz.

The main contents of this thesis are improving a UWB LNA, and analyze the input-matching, the noise, and the gain. First we use the feedback of the input transistor , and it different from the traditional source-degeneration inductor.The design can increase the gain and reduce the noise of the circuit.The second stage CS architecture designed to improve the overall gain of the circuit. Output level to use the source follower with the device even when the output matching . In the input matching,we use a shunt inductor and the impedance of the transistor itself to achieve high frequency matching. The UWB LNA dissipates 16.8 mW power and achieves input return loss (S11) -9.3 to -10 dB, output return loss (S22) -16.83 to -13 dB, forward gain (S21) 13.8 to 11.6 dB, reverse isolation (S12) below -30 dB, and noise figure (NF) of 2.38~3.31 dB over the 6~10 GHz band of interest. 1-dB compression point (P1dB) of -12.5 dBm and input third-order inter-modulation point (IIP3) of -2.5 dBm are achieved at 6 GHz.

The permeation of CMOS technology to radio frequencies and beyond has fuelled an urgent need for a diverse array of passive and active circuits that address the challenges of rapidly emerging wireless applications. While traditional analog based design approaches satisfy some applications, the stringent requirements of newly emerging applications cannot necessarily be addressed by existing design ideas and compel designers to pursue alternatives. One such alternative, an amalgamation of microwave and analog design techniques, is pursued in this work. A number of passive and active circuits have been designed using a combination of microwave and analog design techniques. For passives, the most crucial challenge to their CMOS implementation is identified as their large dimensions that are not compatible with CMOS technology. To address this issue, several design techniques – including multi-layered design and slow wave structures – are proposed and demonstrated through experimental results after being suitably tailored for CMOS technology. A number of novel passive structures - including a compact 10 GHz hairpin resonator, a broadband, low loss 25-35 GHz Lange coupler, a 25-35 GHz thin film microstrip (TFMS) ring hybrid, an array of 0.8 nH and 0.4 nH multi-layered high self resonant frequency (SRF) inductors are proposed, designed and experimentally verified. A number of active circuits are also designed and notable experimental results are presented. These include 3-10 GHz and DC-20 GHz distributed low noise amplifiers (LNA), a dual wideband Low noise amplifier and 15 GHz distributed voltage controlled oscillators (DVCO). Distributed amplifiers are identified as particularly effective in the development of wideband receiver front end sub-systems due to their gain flatness, excellent matching and high linearity. The most important challenge to the implementation of distributed amplifiers in CMOS RFICs is identified as the issue of their miniaturization. This problem is solved by using integrated multi-layered inductors instead of transmission lines to achieve over 90% size compression compared to earlier CMOS implementations. Finally, a dual wideband receiver front end sub-system is designed employing the miniaturized distributed amplifier with resonant loads and integrated with a double balanced Gilbert cell mixer to perform dual band operation. The receiver front end measured results show 15 dB conversion gain, and a 1-dB compression point of -4.1 dBm in the centre of band 1 (from 3.1 to 5.0 GHz) and -5.2 dBm in the centre of band 2 (from 5.8 to 8 GHz) with input return loss less than 10 dB throughout the two bands of operation.

Different wireless communication systems utilizing different standards and for multiple applications have penetrated the normal people's life, such as Cell phone, Wireless LAN, Bluetooth, Ultra wideband (UWB) and WiMAX systems. The wireless receiver normally serves as the primary part of the system, which heavily influences the system performance. This research concentrates on the designs of several important blocks of the receiver; multi-stage amplifier and low noise amplifier. Two novel multi-stage amplifier typologies are proposed to improve the bandwidth and reduce the silicon area for the application where a large capacitive load exists. They were designed using AMI 0.5 m µ CMOS technology. The simulation and measurement results show they have the best Figure-of-Merits (FOMs) in terms of small signal and large signal performances, with 4.6MHz and 9MHz bandwidth while consuming 0.38mW and 0.4mW power from a 2V power supply. Two Low Noise Amplifiers (LNAs) are proposed, with one designed for narrowband application and the other for UWB application. A noise reduction technique is proposed for the differential cascode Common Source LNA (CS-LNA), which reduces the LNA Noise Figure (NF), increases the LNA gain, and improves the LNA linearity. At the same time, a novel Common Gate LNA (CG-LNA) is proposed for UWB application, which has better linearity, lower power consumption, and reasonable noise performance. Finally a novel practical current injection built-in-test (BIT) technique is proposed for the RF Front-end circuits. If the off-chip component Lg and Rs values are well controlled, the proposed technique can estimate the voltage gain of the LNA with less than 1dB (8%) error.

Accurate indoor geolocation is an important and novel emerging technology for commercial, public safety, and military applications. Since most wireless communication systems used for indoor position location may suffer from dense multipath situation, which leads to a severe degradation of position accuracy. The improved TDOA/AOA(Time Difference of Arrival/ Angle of Arrival) position location for indoor ultra-wide band (UWB) systems in the thesis improves the position accuracy of indoor location by using fine resolution of UWB signals. In the line of sight situation, by means of increasing angle of arrival (AOA) information to time difference of arrival (TDOA) based location to achieve the goal of accurate indoor geolocation and provides non-line of sight (NLOS) error mitigation for time measurement and AOA selection to suppress the impact to position accuracy in NLOS environment. Finally, the extended Kalman filter is used to perform position tracking of the target. In the simulations, the NLOS error in time measurement is produced according to the characteristics of indoor UWB channel. Several assumptions of NLOS errors are made in angular measurement. It is observed that proposed method efficiently mitigates the position error in NLOS environment, and detect if the NLOS exists between base station and mobile station immediately.