In this thesis we propose several novel configurations of bandpass filters (BPFs) with two transmission zeros by using the fractal theory. By means of the fractal theory, the dimension of the proposed BPFs can be effectively reduced. Furthermore, the proposed BPFs can be easily fabricated by using multilayer structure based on low-temperature cofired ceramic (LTCC) technology. Under the condition of the same dielectric thickness and coupling coefficient, we compared the conventional square open-loop BPF with the proposed fractal ones. The results show that the reduction in the dimension of the proposed BPFs is evident. Specifically, the dimension of the proposed Koch¡¦s, Minkowski_1st, and Minkowski_2nd filters can be reduced by about 36.5%, 32%, and 51.5%, respectively. Finally, the simulation and measurement results are reported in this thesis.

This thesis proposes methodology to design a balun with imaginary impedance. Under given specification, including center frequency, size, output impedance, our methodology can be used to evaluate its feasibility of implementation using high-DK LTCC(Low Temperature Cofired Ceramic) process. We then extend the design to incorporate a filter, which can simplify the circuit to reduce the required components. An example of our design operating at 2.4 GHz is implemented. Its size is 1600¡Ñ800¡Ñ650 um3, showing significant miniature. The simulation and measurement results are shown to verify the effectiveness of our design.

This thesis proposes an analytical method to synthesize bandpass filter with multiple transmission zeros. By using the six pre-determined parameters including two reflection zeros, two matching quality factors, and two transmission zeros, the method can exactly synthesize the corresponding prototype of second-order coupled-resonator bandpass filter. The synthesized filters not only can provide two pre-determined transmission zeros in the lower and upper side of the passband, but also can generate an extra transmission zero in the stopband. This thesis presents the prototypes of the bandpass filter and the methods of synthesis in detail. Finally this thesis implements compact LTCC bandpass filters by using the proposed synthesis method for 3.5 GHz WiMAX applications.

A new modified-T equivalent-circuit model for the embedded inductors in LTCC is first introduced in this thesis. The model can predict the parallel, series, and ground resonant frequencies successfully. For the embedded capacitors in LTCC, a £k-equivalent circuit that can include first two resonant frequencies has been used. One example for each model has been established to illustrate the broadband features of the models. Finally, a parameter table is given to evaluate the performance of these embedded LTCC inductors and capacitors.

In the first, we design and implement a Two -Point Voltage-Controlled Oscillator which applied in Open-Loop and Two-Point Close-Loop Modulation Bluetooth transmitter and include Hybrid and CMOS RFIC design. Second, we design six LTCC embedded components including inductors and capacitors. The extraction result via traditional equivalent £kmodel match the simulation and the frequency response of adopted model can accurate to device¡¦s Self-Resonant-Frequency nearby compare with measurement. In the end, we design and implement a LTCC Two-Point Voltage-Controlled Oscillator module and effective ly reduce the module size.

This work deals with the fabrication of closed cavities in Low Temperature Co-Fired Ceramics (LTCC). In recent years, the LTCC ceramics have become widely used in the areas of sensors, MEMS and micro-fluidic applications. When fabricating such devices, it is important that the cavities maintain their compactness and dimensions after the manufacturing process . This is achieved primarily with the right choice of lamination process and its parameters and also by appropriate setting of the firing profile. The theoretical part describes the various steps in the production of LTCC structures and the most common technological processes used for creating structures with cavities and micro - channels . In the practical part are selected laminating procedures performed on the test pattern, which contains cavities of different sizes. Emphasis was placed on the correct execution of each method , while gradually modifying the lamination parameters. The achieved results are further discussed in terms of process parameters and their influence on the dimensions of manufactured cavities.

Les systèmes embarqués dans les aéronefs comme dans les véhicules spatiaux doivent impérativement se conformer aux impératifs de masse et de volume mais aussi de coût. Les modules actifs pour antenne à balayage électronique constituent, dans ce cadre, un enjeu stratégique majeur en termes de masse, de volume et de fiabilité. Dans une antenne à balayage électronique actuelle, on peut trouver jusqu’à 1000 modules, chacun étant équipé d’un circulateur-isolateur afin de garantir ses performances. La technologie des circulateurs et des isolateurs à ferrite reste la plus performante en termes d’isolation et de pertes d’insertion. Elle est de plus totalement passive et ne demande aucune énergie extérieure pour son fonctionnement. Elle reste néanmoins coûteuse car la fabrication industrielle de ces dispositifs consiste à assembler mécaniquement de nombreuses pièces usinées précisément : céramiques magnétiques et diélectriques, aimants, conducteurs en cuivre et pièces en métal magnétique doux. De plus, le niveau d’intégration recherché nécessite de réduire les dimensions sans augmenter les pertes pour des niveaux de puissance qui peuvent être importants. S’inspirant des composants céramiques multicouches (condensateurs et inductances) ainsi que de la technologie LTCC (Low Temperature Cofired Ceramics), une nouvelle voie de fabrication de ces composants, en rupture avec les technologies d’assemblage traditionnelles, est abordée dans ces travaux de thèse. L’idée consiste à réaliser par cofrittage le cœur du composant qui est le plus délicat à ajuster et qui détermine le volume final. Les ferrites qui constituent actuellement le cœur des circulateurs sont principalement des grenats ferrimagnétiques fabriqués par des techniques céramiques classiques et frittés à haute température (> 1400°C). Pour les rendre compatibles de la technologie LTCC, il est nécessaire de diminuer leur température de frittage. Les températures visées doivent être inférieures à 1000°C pour pouvoir cofritter avec des parties métalliques en or et si possible être proches de 900°C pour espérer cofritter avec de l’argent. Dans ce contexte, l’objectif de ce travail de thèse était de mettre au point des grenats ferrimagnétiques pour des applications en hyperfréquences présentant des températures de frittage proche de 900°C. Ces ferrites ont alors été utilisés pour la réalisation de circulateurs hyperfréquences, composants indispensables dans les systèmes de Radars et de télécommunications. De plus, des études d’optimisation des propriétés magnétiques et diélectriques de ces ferrites ont aussi été réalisées pour adapter le ferrite aux conditions de fonctionnement (gamme de fréquence et niveau de puissance). / Embedded systems in aircraft must comply with the requirements of mass, volume and cost. The active modules of electronic scanning antenna are, in this context, a strategic challenge in terms of mass, volume and reliability. Today, there are up to 1000 modules per antenna, each one containing a circulator-isolator in order to guarantee its performances. The technology of ferrite circulators and isolators remains the most efficient in terms of isolation and insertion losses. It is also fully passive as no external energy is required to work. However this technology is expensive due to complex mechanical assembling of the different materials: magnetic and dielectric ceramics, magnets, conductors made of copper and soft metallic material. The integration of such devices also requires the reduction of dimensions without increasing losses for power levels that can be high. Based on by multilayer ceramic components (capacitors and inductors) as well as Low Temperature Cofired Ceramics (LTCC) technology, a new way of manufacturing these components, is investigated in this PhD work.. The idea is to be able to cofire the heart of the component which is the most difficult to adjust and also determines the final volume. The ferrites which currently constitute the core of the circulators are ferrimagnetic garnets synthetized by using a conventional ceramic process and sintered at high temperature (> 1400°C). To make them compatible with LTCC technology, it is essential to reduce their sintering temperature. The targeted temperatures must be less than 1000°C in order to cofire with gold metal parts and, if possible, close to 900°C for circulators with silver. In this context, the objective of this PhD work was to develop a ferrimagnetic garnet for microwave applications with sintering temperatures close to 900°C. This ferrite was then used for the preparation of microwave circulators which are essential components in radar and telecommunications systems. In addition, studies of optimization of the magnetic and dielectric properties have also been carried out to meet the operating requirements (frequency band and power level).