Yes / The biggest challenge for future 4G systems is the need to limit the energy consumptions of battery-powered and base station devices, with the aim to prolong their operational time and avoid active cooling in the base station. The green wireless communications requires research in areas such as energy efficient RF front end, MAC protocol, networking, deployment, operation, and also the integration of base station with renewable power supply. In this paper, the design concept of energy efficient RF front end is considered in terms of RF power amplifiers at which it represents the workhorse of modern wireless communication systems and inherently nonlinear. The approach of output power back off is to amplify the signal at the linear region to avoid distortion, but this approach suffers from significant reduction in efficiency and power output. To boost the efficiency at wide range of output power and keep the same margin for signal with high crest factor, the load modulation technique with new offset line are employed to operate over the frequency range of 3.4GHz to 3.6GHz band. The performances of load modulation power amplifier are compared with balanced amplifier. The results of 42dBm output power and 62% power added efficiency are achieved.

To support the large growth in wireless devices, such as personal data assistants (PDAs), wireless local area network (WLAN) enabled laptop computers, and intelligent transportation systems (ITS), the FCC allocated three high-frequency bands for unlicensed operation. Of particular interest is the 5-6 GHz Unlicensed National Information Infrastructure (UNII) band intended to support high-speed WLAN applications. The UNII band is further split into three smaller 100 MHz sub-bands: 5.15 - 5.25 GHz; 5.25-5.35 GHz; and 5.725-5.825 GHz. VCOs that can be switched between each of the three UNII sub-bands offer flexibility and optimum phase-locked loop (PLL) design versus non-switchable VCOs. This work presents switched-tank voltage controlled oscillators (VCOs) designed in Motorolaà ­s 0.18 à µm HIP6WRF BiCMOS process that could be used in multiband receivers covering the three UNII sub-bands. The first VCO was optimized for low power consumption. The VCO draws a total of 6.75 mA from a 1.8 V supply including buffer amplifiers. The VCO is designed with a switched-capacitor LC tank circuit that can switch to two center frequencies, 5.25 GHz and 5.775 GHz, with 200 MHz of varactor-supplied tuning range. The simulated output voltage swing is 2.0 V peak-to-peak and is kept constant between sub-bands by an active PMOS load integrated into the biasing circuitry. The second VCO was optimized for a high output voltage swing by replacing the current biasing circuit with a degenerating inductor. This design targeted three center frequencies, 5.2 GHz, 5.3 GHz, and 5.775 GHz, with 100 MHz of tuning range. This design has an output peak-to-peak voltage swing of 5.2 V but consumes an average of 16.5 mA from a 1.8 V supply. The two fabricated circuits exhibit tuning ranges similar to the simulated results; however, the center frequencies of each decrease due to interconnect parasitics there were unaccounted for in the designs. The measured center frequencies are 4.4 GHz and 5.37 GHz for the first design, and 4.4 GHz and 4.7 GHz for the second design (with one state inoperative due to a faulty switch). The phase noise of the fabricated VCO designs was limited primarily by the low quality factor (Q-factor) of the on-chip LC tank circuits. Oscillators referenced with high-Q off-chip components such as quartz crystal references and surface acoustic wave (SAW) resonators in a PLL can exhibit much improved performance; however, these off-chip components add packaging/assembly cost and higher bill of materials, impedance matching issues, and parasitics that can significantly affect performance for RF applications. Thus, there is tremendous incentive for integrating high-Q components on-chip with the eventual goal of consolidating all of the RF/analog/digital components onto a single wireless-enabled chip, commonly called RF system-on-a-chip (SoC). Microelectromechanical (MEM) resonators have received significant attention based on their ability to provide high on-chip Q-factors at RF frequencies using fabrication techniques that are compatible with modern IC processes. MEM resonators transduce electrical signals into extremely low-loss mechanical vibration and vice versa. Consequently, this thesis also describes the modeling, simulation, and fabrication of contour-mode disk-shaped MEM resonators. This resonator geometry is capable of providing high-Q oscillation at frequencies exceeding 1 GHz at sizes easily within the limits of modern photolithography techniques. Finite element analysis is used to predict the frequency response of disk resonators under various operating conditions and to determine variables that are most critical to the resonator design. A silicon-on-insulator (SOI) fabrication process for constructing the disk is also discussed. Finally, the possible future integration of MEM resonators with multiband VCOs in a common IC process is proposed. / Master of Science

A goal of indoor wireless communication is to strategically place RF base stations to obtain optimum signal coverage at the lowest cost and power. Traditionally, transceiver locations have been selected by human experts who rely on experience and heuristics to obtain a near-optimum placement. Current methods depend on involved on-site communication measurements and crude statistical modeling of the obtained data which is time consuming and prohibitive in cost. Given the inherent variability of the indoor environment, such a method often yields poor efficiency. As an example, it is possible that more power than required or extra number of transceivers were used. This thesis describes an interactive software system that can be used to aid transceiver placement. The tool is easy to use and is targeted at users who are not experts in wireless communication system design. Once the transceiver locations are selected by the user within a graphical floor plan, the system uses simple path-loss models to predict coverage regions for each transceiver. The coverage regions are highlighted to indicate expected coverage. Earlier work assumed isotropic transceivers and had limited directional transmitter support. This thesis describes how the tool has been enhanced to support a wide range of 3D antenna patterns as encountered in practical situations. The tool has also been expanded to accommodate more partition types and to report area of coverage. The resulting system is expected to be very useful in the practical deployment of indoor wireless systems. / Master of Science

Indoor wireless communication systems are becoming increasingly prevalent in work environments. The need to quickly and efficiently provide in-building and microcellular coverage without sacrificing quality is critical to cellular and emerging personal communication system (PCS) operators. Traditionally, indoor wireless communication system design has been carried out by human experts relying on experience to determine a satisfactory system configuration. This thesis describes the algorithms and technical considerations implemented in a comprehensive propagation planning tool, SMT Plus, which has been designed to predict the coverage regions of both in-building and microcellular wireless communication systems. The goal of SMT Plus is to provide both wireless service providers and equipment manufacturers with an efficient, easy-to-use coverage prediction tool for use in the design of any indoor or campus-wide wireless system. Using site-specific building information combined with on-site signal strength measurements, the tool provides system planners with a highly accurate model of the propagation environment among a group of buildings. SMT Plus provides a comprehensive solution to the planning and installation of wireless communication systems in and around buildings. / Master of Science

ITC/USA 2010 Conference Proceedings / The Forty-Sixth Annual International Telemetering Conference and Technical Exhibition / October 25-28, 2010 / Town and Country Resort & Convention Center, San Diego, California / RF Communication (COMMS) systems where receivers and transmitters are in motion must be proven rigorously over an array of natural RF link perturbations such as Carrier Doppler shift, Signal Doppler shift, delay, path loss and noise. These perturbations play significant roles in COMMS systems involving satellites, aircraft, UAVs, missiles, targets and ground stations. In these applications, COMMS system devices must also be tested against increasingly sophisticated intentional and unintentional interference, which must result in negligible impact on quality of service. Field testing and use of traditional test and measurement equipment will need to be substantially augmented with physics-compliant channel emulation equipment that broadens the scope, depth and coverage of such tests, while decreasing R&D and test costs and driving in quality. This paper describes dynamic link emulation driven by advanced antenna and motion modeling, detailed propagation models and link budget methods for realistic, nominal and worst-case hardware-in-the-loop test and verification.

Ces travaux s'inscrivent dans un contexte où les contraintes vis-à-vis des décharges électrostatiques sont de plus en plus fortes, les circuits de protection sont un problème récurrent pour les circuits fonctionnant à hautes fréquences. La capacité parasite des composants de protection limite fortement la transmission du signal et peut perturber fortement le fonctionnement normal d'un circuit. Les travaux présentés dans ce mémoire font suite à une volonté de fournir aux concepteurs de circuits fonctionnant aux fréquences millimétriques un circuit de protection robuste présentant de faibles pertes en transmission, avec des dimensions très petites et fonctionnant sur une très large bande de fréquences, allant du courant continu à 100 GHz. Pour cela, une étude approfondie des lignes de transmission et des composants de protection a été réalisée à l'aide de simulations électromagnétiques et de circuits. Placés et fragmentées le long de ces lignes de transmission, les composants de protection ont été optimisés afin de perturber le moins possible la transmission du signal, tout en gardant une forte robustesse face aux décharges électrostatiques. Cette stratégie de protection a été réalisée et validée en technologies CMOS avancées par des mesures fréquentielles, électriques et de courant de fuite. / Advanced CMOS technologies provide an easier way to realize radio-frequency integrated circuits (RFICs). However, the lithography dimension shrink make electrostatic discharges (ESD) issues become more significant. Specific ESD protection devices are embedded in RFICs to avoid any damage. Unfortunately, ESD protections parasitic capacitance limits the operating bandwidth of RFICs. ESD protection size dimensions are also an issue for the protection of RFICs, in order to avoid a significant increase in production costs. This work focuses on a broadband ESD solution (DC-100 GHz) able to be implemented in an I/O pad to protect RFICs in advanced CMOS technologies. Thanks to the signal transmission properties of coplanar / microstrip lines, a broadband ESD solution is achieved by implementing ESD components under a transmission line. The silicon proved structure is broadband; it can be used in any RF circuits and fulfill ESD target. The physical dimensions also enable easy on-chip integration.

Ce manuscrit présente une étude de la susceptibilité d’un amplificateur faible bruit (LNA)AsGa aux agressions électromagnétiques de forte puissance. La notion d’agressionélectromagnétique de forte puissance définit, du point de vue de la CEM, un environnementélectromagnétique particulier où les niveaux de champ électromagnétique sont tels qu’ilspeuvent engendrer une dégradation physique des composants électroniques du systèmevictime. Ces champs peuvent être générés par des systèmes particuliers appelés AED EM(arme à énergie dirigée électromagnétique).Cette étude s’intéresse ainsi non seulement à l’explication des effets physiques observés surles composants cibles, mais également à l’influence des paramètres de la sourceélectromagnétique sur la susceptibilité du composant.Cette thèse a été encadrée par les équipes du laboratoire IMS de l’université de Bordeauxd’une part, et du CEA Gramat d’autre part. / In this PhD thesis dissertation, a study of a GaAs low-noise amplifier (LNA) susceptibility tohigh power electromagnetic interference is presented.The term high power electromagnetic interference refers to a particular electromagneticenvironment in which E-field and H-field levels are high enough to cause physical damage tothe victim’s system electronic components.Such high level fields can be generated by dedicated systems, called electromagneticdirected energy weapons (DEW).The study presented in this document focuses not only on explaining failure mechanismstriggered by such interference, but also shows discussion on electromagnetic sourcesparameters trimming influence on component’s susceptibility.

Dans de nombreuses applications, des paquets d’électrons relativistes sub-ps sont requis : Accélération laser-plasma, Lasers à électrons libres, Génération de rayonnement THz intense, Etude des phénomènes ultra-rapides dans la matière… L’aspect court des paquets et la nécessité d’un fort courant crête pour les applications impliquent de fortes forces de charge d’espace conduisant à une dégradation des propriétés du faisceau, telle que son émittance transverse et sa longueur. La principale difficulté est de caractériser, modéliser et prendre en compte ces effets. Ma thèse s’inscrit dans ce cadre à travers l’étude de la dynamique et des diagnostics associés à ces paquets courts. Le chapitre 2 rassemble des mesures de plusieurs propriétés du faisceau : charge, émittance transverse et longueur. L’originalité de mon travail réside dans l’utilisation de méthodes simples, des points de vues théoriques et technologiques. Ces méthodes, plus adaptées pour des faisceaux moins extrêmes, permettent néanmoins d’obtenir de très bons résultats. J’ai en particulier développé une méthode de mesure de charge à partir de la mesure de l’intensité lumineuse émise par un écran scintillant suite à l’interaction avec le faisceau. Cette méthode permet de mesurer précisément des charges inférieures à 100 fC, ce qui surpasse les capacités des diagnostics classiques (ICT et Coupe de Faraday) limités au picocoulomb à cause du bruit électronique. Cette méthode est utile, du fait que les paquets courts sont souvent faiblement chargés pour limiter l’effet des forces de charge d’espace. J’ai aussi adapté des méthodes multiparamétriques pour mesurer l’émittance transverse et la longueur des paquets d’électrons. Ces méthodes indirectes permettent de déterminer ces propriétés à partir de la mesure d’autres propriétés plus accessibles : les dimensions transverses pour l’émittance et la dispersion en énergie pour la longueur. La mesure de longueur (méthode des 3 phases) donne de très bons résultats, puisqu’elle permet de mesurer avec une précision meilleure que 10% des longueurs rms inférieures à la picoseconde. La mesure d’émittance sans prise en compte des forces de charge d’espace donne des résultats mitigés, puisque la précision varie de 20% (méthode des 3 gradients) à plus de 100% (méthode des 3 écrans). Une amélioration significative de la précision, jusqu’à un facteur 5, peut être obtenue en prenant en compte les forces de charge d’espace via une équation d’enveloppe, ce qui constitue l’originalité de mon travail. Le chapitre 3 consiste en une comparaison des propriétés des paquets courts d’électrons, unique ou longitudinalement modulé, générés par trois méthodes différentes : Utilisation d’une impulsion laser courte ou longitudinalement modulée dans un canon RF ; Compression magnétique dans une chicane ; Compression RF dans une structure accélératrice (Velocity Bunching). J’ai en particulier montré que, à charge égale, la génération de paquets courts via une impulsion laser courte dans un canon RF est désavantageuse, des points de vue de la longueur et de l’émittance transverse du faisceau, par rapport à la compression magnétique RF d’un paquet déjà accéléré. Cela est expliqué par les forces de charge d’espace plus importantes juste après l’émission du faisceau par la photocathode. Il est également consacré au développement et au test de modèles analytiques de la dynamique longitudinale des faisceaux. J’ai développé une matrice de transfert longitudinale pour un canon RF, en partant du modèle de K. J. Kim. Ce modèle a été comparé avec plusieurs mesures effectuées à PITZ et PHIL et a prouvé être précis sur les aspects énergétiques et temporels, mais pas sur l’aspect de la dispersion en énergie. J’ai également développé un modèle analytique du phénomène de velocity bunching dans des structures accélératrices à onde progressive, en partant d’un modèle simple développé par P. Piot. / In several applications, quasi-relativistic sub-ps electron bunches are required: Laser-plasma acceleration, Free electron lasers, Generation of intense THz radiation, Study of ultra-fast phenomena in matter… The short nature of the bunch and the necessity of a high peak current for the applications imply strong space-charge forces leading to a degradation of beam properties, as its transverse emittance and duration. The main difficulty is to characterize, model and take into account these effects. My thesis falls within this context through the study of dynamics and diagnostics related to these short bunches, namely whose rms duration is not directly measurable by an electronic method locating the border at a few tens of picoseconds. The chapter 2 consists in the measurements of several properties of these bunches: charge, transverse emittance and duration. The originality of my work is that I use simple methods, both on the theoretical (analytical at maximum) and technological (using only common elements of electron accelerators) point of view. These methods, more suitable for less extreme bunches, allow however obtaining very good results. I especially developed a method of charge measurement from the measurement of the light intensity emitted by a scintillating screen following the interaction with an electron beam. This method allows precisely measuring charges lower than 100fC. This is better than the capabilities of classical diagnostics (ICT and Faraday Cup) limited to the picocoulomb because of electronic noise. This method is useful since the short bunches are often low-charged to minimize the effects of space-charge forces. It will also be used for detectors calibration, which requires low charges. I also adapt multiparametric methods to measure the transverse emittance and duration of electron bunches. These indirect methods allow determining these properties from the measurement of other more accessible properties: the transverse dimensions for the transverse emittance and the energy spread for the duration. The duration measurement (3-phase method) gives very good results, since it allows determining with accuracy better than 10% rms durations lower than one picosecond. The emittance measurement without taking into account the space-charge forces in the modeling gives mixed results, since the accuracy is from 20% (3-gradients method) to more than 100% (3-screens method). A significant accuracy improvement, up to a factor of 5, can be obtained by taking the space-charge forces into account through a beam envelop equation, which constitutes the originality of my work. The chapter 3 consists in the comparison of the properties of short electron beams, single or longitudinally modulated, generated by three different methods: Injection of a short or longitudinally modulated laser pulse in an RF-gun; Magnetic compression in a chicane; RF-compression in an accelerating structure (Velocity Bunching). I particularly shown that, at equal conditions of charge, the generation of short bunches thanks to a short laser pulse driven an RF-gun is disadvantageous, both from the beam duration and transverse emittance point of view, with respect to a magnetic or RF compression of an already accelerated beam. This is explained by the more important space-charge forces just after the beam emission by the photocathode. It also consists in the development and test of analytical models for longitudinal beam dynamics. I developed a longitudinal transfer matrix for RF-gun, starting from a Kim-like model. This model has been compared with several measurements performed at PITZ and PHIL and shown to be accurate on the energy and temporal aspects, but not on the energy spread aspect. I also developed an analytical model of the velocity bunching phenomenon in travelling wave accelerating structures, starting from a simple model developed by P. Piot.

Neste trabalho foi feita uma ampla pesquisa sobre blocos de RF, VCOs e LNAs, que fazem parte de transceptores. Esses blocos foram projetados utilizando um indutor externo com um alto Q, com o intuito de melhorar as principais características de desempenho de cada um dos blocos. Com a finalidade de ter um ponto de comparação foram projetados os mesmos blocos implementando todos os indutores integrados (internos). Foi proposta a utilização da tecnologia flip chip para interconectar os indutores externos aos dies dos circuitos, devido às vantagens que ela apresenta. Para implementar os indutores externos propôs-se um processo de fabricação completo, incluindo especificação das etapas de processos e dos materiais utilizados para estes indutores. Adicionalmente foi projetado um conjunto de máscaras para fabricar os indutores externos e fazer a montagem e teste dos circuitos que os utilizam. Para validar o processo proposto e caracterizar os indutores externos foram projetadas diferentes estruturas de teste. O Q do indutor externo é da ordem de 6 vezes maior que do indutor integrado, para a tecnologia escolhida. Foram projetados e fabricados dois VCOs LC: FC-VCO (Flip Chip VCO com o indutor externo), OC-VCO (On Chip VCO com o indutor interno), e dois LNAs CMOS de fonte comum cascode com degeneração indutiva: FC-LNA (Flip Chip LNA com o indutor Lg externo) e OC-LNA (On Chip LNA com todos os indutores internos). O objetivo desses quatro circuitos é demonstrar que o desempenho de circuitos RF pode ser melhorado, usando indutores externos com alto Q, conectados através de flip chip. Para implementação desses circuitos utilizou-se a tecnologia de processo AMS 0,35µm CMOS, para aplicações na banda 2,4GHz ISM, considerando o padrão Bluetooth. Foram medidos apenas os blocos com os indutores internos (OC-VCO e OC-LNA). Para os blocos com os indutores externos (FC-VCO e FC-LNA) foram apresentados os resultados de simulação pós-layout. Através da comparação dos resultados de simulação entre os VCOs foi comprovado que o uso de um indutor externo com alto Q conectado via flip chip pode melhorar significativamente o ruído de fase dos VCOs, atingindo -117dBc/Hz a 1MHz de frequência de offset para o FC-VCO, em 2,45GHz, onde a FOM é 8dB maior que o OC-VCO. Outro ganho foi através da área poupada, o FC-VCO tem uma área cerca de 83% menor que a do OC-VCO. Após as medidas elétricas do OC-VCO obteve-se um desempenho do ruído de fase de -110dBc/Hz@1MHz para 2,45GHz, e -112dBc/Hz@1MHz para 2,4GHz, o qual atende as especificações de projeto. O FC-LNA, que foi implementado com o indutor de porta Lg externo ao die, conectado via flip chip, atingiu uma figura de ruído de 2,39dB, 1,1dB menor que o OC-LNA com o mesmo consumo de potência. A área ocupada pelo FC-LNA é aproximadamente 30% menor do que o OC-LNA. Através das medidas elétricas do OC-LNA verificou-se que o circuito apresenta resultados adequados de S11 (perda de retorno da entrada) e S22 (perda de retorno da saída) na banda de frequências de interesse. No entanto, o valor do ganho apresenta uma redução em relação ao esperado. A proposta do trabalho de unir a tecnologia flip chip ao uso de indutores externos, proporciona circuitos mais compactos e consecutivamente mais baratos, pela economia de área de Si. Adicionalmente, após os indutores externos serem caracterizados, os mesmos indutores podem ser reutilizados independente da tecnologia CMOS utilizada facilitando o projeto dos blocos de RF em processos mais avançados. / This work presents a research about RF blocks that are used in Transceivers, VCOs and LNAs. These blocks were designed using a high-Q RF external inductor in order to improve the main performance characteristics. The same blocks were designed implementing all inductors on-chip (internal) in order to have a point of comparison. It was proposed the use of Flip Chip technology to interconnect the external inductors to the dies of the circuits due to the advantages that this technology offers. A full manufacturing process was proposed to implement the external inductors, including the specification of process steps and materials used for these inductors. Additionally, a set of masks was designed to fabricate the external inductors, to mount and test the circuits that used these inductors. Different test structures were designed to validate the proposed process and to characterize the external inductors. Q factor of the external inductor is around 6 times larger than the inductor integrated into the chosen IC technology. Two LC VCOs and two common-source cascode CMOS LNAs with inductive degeneration were designed and fabricated: FC-VCO (Flip Chip VCO using external inductor), OC-VCO (On Chip VCO using on-chip inductor), FCLNA (Flip Chip LNA using an external Lg inductor) and OC-LNA (On Chip LNA with all inductors implemented on-chip). The purpose of these four circuits is to demonstrate that the performance of RF circuits can be improved by using high-Q external inductors, connected by flip chip. The 0.35µm CMOS AMS technology was used to implement these circuits intended for applications in the 2.4 GHz ISM band, considering the Bluetooth standard. Were measured only the blocks with internal inductors (OC-VCO and OC-LNA). For the blocks with external inductors (FCVCO and FC-LNA) were presented the results of post-layout simulation. The comparison between the VCOs simulations results demonstrates that using an external high-Q inductor connected by flip chip can significantly improve the phase noise of VCOs. FC-VCO reached a phase noise of -117dBc/Hz at 1MHz offset frequency and a FOM 8dB greater than the OC-VCO. Another important improvement was the saved area, the FC-VCO has an area approximately 83% lower than that of OC-VCO. After electrical characterizations of the OC-VCO, phase noise performances of -110dBc/Hz@1MHz for 2.45GHz and -112dBc/Hz@1MHz for 2.4GHz were obtained, that accomplish the design specifications. FC-LNA reached a noise figure of 2.39dB, 1.1dB lower than that of OC-LNA with the same power comsumption. The total area occupied by FC-LNA is around 30% lower than that OC-LNA. Measurement results of the OC-LNA showed that the circuit presents suitable S11 (input return loss) and S22 (output return loss) values in the desired frequency band. However, the gain value presents a reduction compared with the expected values. The proposal to use the flip chip technology together with external inductors, allows more compact and cheap circuits, because Silicon area can be saved. Moreover, after the external inductors being characterized, the same inductors can be reused regardless of the CMOS technology facilitating the design of RF blocks in more advanced processes.

Este trabalho descreve o desenvolvimento de um sistema integrado transdutor/bobinas de gradientes de alto desempenho para Imagens por Ressonância Magnética. Este sistema é composto por um transdutor de radiofreqüência tipo sela e um conjunto de 3 bobinas locais assimétricas. No desenho do transdutor foram otimizados os parâmetros: relação sinal ruído e uniformidade do campo magnético por ele gerado. A densidade de corrente de cada bobinas local foi otimizada mediante técnicas numéricas estocásticas para gerar um gradiente de campo magnético uniforme em cada uma das 3 direções do espaço numa região das dimensões do crânio. O conjunto de bobinas de gradientes construído possui um diâmetro livre de 31.5 cm e gera em média 25 mT/m/A por bobina, com indutâncias inferiores a 310 mH. São mostradas as aplicações clínicas desenvolvidas nas áreas de imagens tridimensionais e angiografia, a partir das seqüências de pulsos implementadas e aproveitando o uso do sistema integrado, em um tomógrafo de ressonância magnética de 0.5 Tesla. Imagens de phantom foram adquiridas em menos de 500 ms usando o conjunto integrado e técnicas do tipo Echo Planar Imaging. Aspectos referentes à caracterização e correção de campos magnéticos estáticos e homogêneos são também comentados. As soluções descritas nesta tese têm um amplo conteúdo tecnológico e beiram nas fronteiras da Física Aplicada e a Engenharia Biomédica. / Here we describe the development of a high performance radio-frequency/gradient coil integrated system for Magnetic Resonance Imaging. A saddle radio-frequency coil and a three-axis asymmetric local gradient coil composed this system. Two parameters were optimized in the RF coil design: signal-to-noise ratio and magnetic field uniformity. The current density of each local coil was optimized using stochastic numerical techniques, in order to generate a uniform magnetic field gradient by axis in a region representing a human head. The build gradient coil set has an inner diameter of 31 cm. The average gradient efficient of the three-axis is 25 mT/m/A and the maximum inductance is less than 310 mH. We show the clinical applications performed in three-dimensional and angiography imaging areas in a 0.5 Tesla magnetic resonance tomograph. These applications were optimized to taking advantage from the integrated system. Phantom images were acquired in less than 500 millisecond using echo planar techniques and the integrated set. Some aspects about static and homogeneous magnetic field characterization and correction are also commented. In this work we described solutions with wide technologic content close to the boundaries of the Applied Physics and Biomedical Engineering.