L’objectif de cette action R&T CNES est le développement en technologie intégrée SiGe BiCMOS d’un core-chip MMIC pour les antennes à formation de faisceaux. Les nouvelles solutions pour les charges satellites développées pour les applications télécom notamment ont besoin d’être de plus en plus flexibles. Cela passe par la mise en place d’un très grand nombre de points de contrôle RF ‘Amplitude/Phase’ qui alimentent les antennes actives. Il faut donc de nouvelles solutions pour optimiser ces fonctions. Ces solutions doivent répondre à plusieurs critères : être compactes, diminuer la consommation DC et conserver les mêmes niveaux de performance en termes de gain, résolution et linéarité que les solutions déjà en place. Dans ce contexte, notre projet de recherche a porté sur le développement de circuits déphaseurs et atténuateurs en technologie SiGe. Une étude préliminaire a permis d’évaluer la technologie en réalisant un premier run comprenant des cellules de déphasage et d’atténuation élémentaires. Des lignes de transmission de type Slow Wave Lines ont également été intégrées afin de montrer leur potentiel pour des applications futures. Ces premiers résultats ont conduits à réaliser un second run comprenant des circuits plus avancés ainsi que le test d’une nouvelle technique pour le design des transistors : le body floating. Cette technique nous a permis de diminuer les pertes de nos circuits tout en améliorant la linéarité. Un troisième run incluant un déphaseur et un atténuateur 4 bits a permis de confirmer les modèles de simulations et le potentiel des circuits MMIC en technologie SiGe. Un dernier run a enfin permis de réaliser un nouveau type de SWL et de réaliser des solutions alternatives aux circuits classiques basées sur ces dernières. / This R&T CNES project concerns the design and realization of a Core-chip MMIC system integrated in SiGe BiCMOS technology. The MMIC core-chip system is dedicated to the beamforming for the active satellite antenna. The new solutions for the satellite payloads being developed for telecommunication applications need an increased flexibility at all the levels. More precisely, the system of active antennas allowing an adjustment by real-time electronic command of the terrestrial covered area offers an optimized response for the communication link budget. This performance has a cost: the necessity of a very large number of RF control points "amplitude / phase" of the beamforming equipment which power the active antenna matrix elements. So, it becomes mandatory to bring a new solution to optimize this function. The main challenges are: increasing the functions integration, decreasing the DC power consumption and keeping the RF performances in terms of gain, resolution and linearity.

The acoustoelectric effect in graphene is studied in a graphene/lithium niobate hybrid system, which was prepared by transferring large area single-layer graphene grown on copper onto lithium niobate SAW devices. The transfer of momentum from the surface acoustic waves (SAWs), generated on the surface of the lithium niobate, to the carriers in graphene results in an attenuation and velocity shift of the wave, and gives rise to an acoustoelectric current. The acoustoelectric current, and the amplitude and velocity of the SAW are measured using a sourcemeter and oscilloscope, respectively. Macroscopic acoustoelectric current flowing over several hundred micrometers is demonstrated in graphene, which is measured to be directly proportional to the SAW intensity and frequency at room temperature. A relatively simple classical relaxation model, which describes the piezoelectric interaction between SAWs and the carriers in a two-dimensional electron system, is used to explain the experimental observations. The investigation of the acoustoelectric current as a function of temperature demonstrates the ability of SAWs of different wavelengths to probe graphene at different length scales. By tuning the conductivity of the graphene through the use of a top gate, voltage-controlled phase (velocity) shifters are demonstrated. The acoustoelectric current measured as a function of gate voltage demonstrates that an equal density of electrons and holes are transported at the charge neutrality point, reflecting the unique properties of graphene.

With the advancement in wireless communication, there has been a lot of overlap in the frequency spectrum used by different applications in the lower frequency band. Also there is an ever-increasing demand for high-speed wireless data transfer. Due to the aforementioned reasons, a lot of work is being done recently in the unlicensed 60GHz bandwidth due to the high data rates it can support. But it is tough to achieve long-range point-to-point transmission at this frequency due to the limited output power and high path losses. A phased array system is a viable solution at these mmWave frequencies to achieve highly directive long-range point-to-point communication. The objective of this research is the design and implementation of phase shifters, VCO and LNA for mmWave phased array system. In this work, active and passive quadrature generation schemes integrated with a vector modulator have been proposed that can be used to produce arbitrary phase shift with a deterministic resolution at the LO signal. Also, alternate IF and PLL based phase shifting schemes for a mmWave phased array system have been proposed. A complete design procedure from parasitic modeling of devices to verification of the design using EM simulations has been discussed in this work. The simulation results are compared with actual measurement results from the fabricated chip and the performance of the various circuits has been analyzed. Furthermore, the designs of VCO and low noise amplifier to be used in the mmWave phased array system are discussed here.

This thesis presents the design of radio-frequency (RF) tunable active inductors (TAIs) with independent inductance (L) and quality factor (Q) tuning capability, and their application in the design of RF tunable phase shifters and directional couplers for wireless transceivers. The independent L and Q tuning is achieved using a modided gyrator-C architecture with an additional feedback element. A general framework is developed for this Q- enhancement technique making it applicable to any gyrator-C based TAI. The design of a 1.5V, grounded, 0.13um CMOS TAI is presented. The proposed circuit achieves a 0.8nH-11.7nH tuning range at 2GHz, with a peak-Q in excess of 100. Furthermore, printed and integrated versions of tunable positive/negative refractive index (PRI /NRI) phase shifters, are presented in this thesis. The printed phase shifters are comprised of a microstrip transmission-line (TL) loaded with varactors and TAIs, which, when tuned together, extends the phase tuning range and produces a low return loss. In contrast, the integrated phase shifters utilize lumped L-C sections in place of the TLs, which allows for a single MMIC implementation. Detailed experimental results are presented in the thesis. As an example, the printed design achieves a phase of -40 to +34 degrees at 2.5GHz. As another application for the TAI, a reconfigurable CMOS directional coupler is presented in this thesis. The proposed coupler allows electronic control over the coupling coefficient, and the operating frequency while insuring a low return loss and high isolation. Moreover, it allows switching between forward and backward operation. These features, combined together, would allow using the coupler as a duplexer to connect a transmitter and a receiver to a single antenna. Finally, a planar electronically steerable patch array is presented. The 4-element array uses the tunable PRI/NRI phase shifters to center its radiation about the broadside direction. This also minimizes the main beam squinting across the operating bandwidth. The feed network of the array uses impedance transformers, which allow identical interstage phase shifters. The proposed antenna array is capable of continuously steering its main beam from -27 to +22 degrees of the broadside direction with a gain of 8.4dBi at 2.4GHz.

A reflection retarder is a device that induces a change in the phase between the parallel and perpendicular components, of the electric field, to the plane of incidence while maintaining the relative amplitudes. A film-substrate reflection retarder is a reflection retarder that only consists of a film-substrate system. Film-substrate reflection retarders have been previously studied in the negative, zero, and positive systems. The type of system is determined by the relationship between the refractive index of the ambient N0, film N1, and substrate N2: if N1<(N0*N2)^(1/2) , the system is negative; if N1=(N0*N2)^(1/2), the system is zero; if N1>(N0*N2)^(1/2), the system is positive. It has been determined that is the condition required to achieve reflection retarders, in general. Angle-of-incidence tunable (AIT) retarder designs have not been investigated for the zero system, but have been studied in the negative system. An exact retarder in the zero system only exists at a single angle of incidence and a corresponding single film thickness. By approximating the retarder condition to allow the relative amplitudes to be within 5% of the exact value of unity, it is possible to realize unique AIT retarders in the zero system: retarders that can be operated over a continuous range of angles of incidence resulting in a large range of phase shifts approaching 360°. It is possible to have multiple angles of incidence with a difference of between their respective phase shifts. By inducing a phase shift of, it is possible to modulate the polarization of light. By employing an approximation of the retarder condition, AIT retarder designs were developed. The design’s tolerance to changes in design parameters is analyzed and discussed.

Thesis (M. Eng.)--Carleton University, 2001. / Includes bibliographical references (p. 171-174). Also available in electronic format on the Internet.

Thesis (Ph. D.)--University of Washington, 2006. / Vita. Includes bibliographical references (leaves 150-155).

Les réseaux réflecteurs imprimés connaissent un fort développement depuis la fin des années 80. Ce type d’antenne offre la possibilité de former des diagrammes de rayonnement complexes avec une relative simplicité, un faible coût de réalisation, de faibles pertes et un volume réduit. Cependant, il souffre encore de quelques défauts : - La non régularité de la géométrie de la cellule sur la surface du réseau, dans le cas d’une antenne passive, peut engendrer des dégradations sur le diagramme de rayonnement, surtout à la transition entre deux géométries extrêmes, lorsqu’un nouveau cycle de phase commence. - Le nombre relativement élevé de composants utilisés pour contrôler la phase de l’onde réfléchie, dans le cas d’une antenne reconfigurable, augmente le coût de fabrication de l’antenne et complexifie le circuit de commande des éléments reconfigurables. - La limitation en bande passante, qui a longtemps cantonné ce type d’antenne à des applications bande étroite, est principalement liée au comportement de la cellule unitaire constitutive du réseau. Dans cette thèse, nous nous intéressons donc à la conception de nouvelles topologies de cellules déphaseuses, passives et surtout reconfigurables, qui permettent, tout en conservant une relative simplicité de réalisation, d’offrir une large bande passante. De plus, le contrôle de la phase, dans le cas des cellules reconfigurables, doit être réalisé avec un nombre réduit de composants afin de respecter la contrainte de faible coût de fabrication. / Microstrip printed reflectarrays experience strong development since the late 80s. This type of antenna has the potential to form complex radiation patterns with relative simplicity, low cost, low losses and low profile. However, it still has some shortcomings: - The non-regularity of the geometry of the cell on the surface of the array, in the case of passive antenna, may cause degradation on the radiation pattern, especially at the transition between two extreme geometries, when a new phase cycle begins. - The high number of components used to control the phase of the reflected wave, in the case of reconfigurable antenna, increases the manufacturing cost of the antenna and complicates the control circuit of the reconfigurable elements. - The limited bandwidth has long confined this type of antenna to narrowband applications and is mainly due to the intrinsic bandwidth of the unit cell. In this thesis, we therefore focus on the design of new, passive and reconfigurable, phase-shifting cells that can provide a wide bandwidth while maintaining a simple implementation. In addition, the control of the phase, in the case of reconfigurable cells, must be made with a reduced number of components in order to comply the constraint of low manufacturing cost.

Cette thèse, menée en partenariat avec le CNES et la DGA s’inscrit dans un contexte international très actif sur les réseaux réflecteurs ou reflectarrays. Un reflectarray est constitué d’une source primaire placée au-dessus d’un réseau de cellules contrôlant les propriétés du champ réfléchi. Une reconfiguration du diagramme de rayonnement peut être réalisée de manière électronique en introduisant des éléments actifs dans chacune des cellules. Dans ce contexte, le travail réalisé a consisté à étudier une nouvelle topologie de cellule permettant de réfléchir indépendamment deux ondes incidentes, en polarisations circulaires gauche et droite, en bande X. Cette cellule, basée sur la superposition d’une cellule sélective en polarisation et d’une cellule simple polarisation, est conçue de façon à être compatible avec une reconfiguration électronique à l’aide de commutateurs. Après un important travail de simulation électromagnétique, une première validation expérimentale, menée à l’échelle de la cellule unitaire, a mis en évidence de très bonnes performances dans les deux polarisations (pertes inférieures à 1dB, déphasage atteignant 2 bits de résolution). A cette occasion, un banc de caractérisation spécifique a été développé. Une étude de faisabilité de la cellule reconfigurable a également été menée afin d’identifier les technologies de commutateur les plus pertinentes et de quantifier les perturbations apportées par la circuiterie de commande. Finalement, un démonstrateur de réseau à états figés a été réalisé et mesuré. Constitué de 97 cellules, il a permis de démontrer les potentialités de la structure développée, pour une application spatiale réaliste : dépointage jusqu’à 26°, bande passante de 800 MHz en bande X, réjection de polarisation croisée>20dB correspondant à une pureté de polarisation circulaire satisfaisante (TE<2dB). Il s’agit de la première antenne à réseau réflecteur qui permette de gérer indépendamment et simultanément les deux orientations de la polarisation circulaire à la même fréquence tout en offrant des capacités de reconfigurabilité. / This thesis done in partnership with the French Space Agency (CNES) and the French Defense Agency (DGA) is placed in a very active international context on reflectarrays antennas. A reflectarray consists of a primary source located above microstrip elements on a grounded substrate. The microstrip elements are designed to reradiate the incident wave. A reconfiguration of the radiation pattern can be electronically achieved by introducing switches in each element. In this context, for space applications in X-band, the objective of this thesis is to propose a dual-circular polarization (CP) unit-cell able to separate at the same frequency, the two incident circular polarizations. This unit-cell, made of two layers with reconfigurable capabilities, is based on a circular polarization selective surface (CPSS) and on a single polarization cell. After intensive electromagnetic simulations, the unit-cell in dual-circular polarization with reconfigurable capabilities has been experimentally validated using a specific waveguide measurement. In fact, the unitcell reflects independently and simultaneously the two incidents circular polarizations for a phase resolution around 2 bits in LHCP and in RHCP. A feasibility study of the reconfigurable cell was also carried out to identify the most relevant technologies. Then, a reflectarray in X-band has been designed, fabricated and measured. Made up of 97 cells, it has demonstrated the potentialities of the structure for a realistic space application: scan angle up to 26 °, bandwidth of 800MHz in X-band, cross-polarization rejection>20dB and good polarization purity (AR<2dB). This is the first time that a dual circular polarization reflectarray with reconfigurable capabilities has been validated with the unique capability to reflect independently and simultaneously the two incident circular polarization at the same frequency.

The recent years have witnessed an unprecedented growth in the number of connected devices and amount of bandwidth required by the multiple services offered by wireless devices. The current 5G standard addresses such issues by adopting higher carrier frequencies and antennas with a large number of radiating elements. The former solution enables to exploit larger bandwidths in the millimeter-wave (mmWave) portion of the spectrum, while the latter one allows access points to serve an increasingly higher number of users. Both find realization in the Multiple-Input-Multiple-Output (MIMO) antenna systems with their enhanced beamforming capabilities. While the adoption of the hybrid digital-analog beamforming architecture lightens the overall system complexity, the need of miniaturized, high-performance and broadband hardware components is still an open issue. Passive Radio Frequency (RF) components in MicroElectroMechanical-Systems technology (RF-MEMS) offer notable and broadband electrical performances, while maintaining the marked miniaturization required for the hardware to be employed in the MIMO antennas, characterizing the current and future telecommunications scenario. Whilst numerous examples of single RF-MEMS switches, attenuators and phase shifters are available in the literature since about two decades, still limited attention is dedicated to the development of MEMS-based multi-device monolithic networks embedding such devices. High-performance RF-MEMS networks of this kind could represent the base of future MIMO beamforming architectures. Given such a context, the fundamental core of this thesis is the design and the realization of ad hoc RF-MEMS devices to be integrated in a reconfigurable monolithic module, operating in the realistic scenario of the mm-Wave portion of the spectrum allocated to 5G in Europe (24.25–27.5 GHz). The resulting devices consist in a 3-bit attenuator, three 1-bit phase-shifting cells and a Single-Pole-Double-Throw (SPDT) switch, each relying on membranes featuring a reduced actuation voltage, in the 5–9 V range, for an easier interfacing with electronics based on Complementary Metal–Oxide–Semiconductor (CMOS). To this purpose, the ad hoc designed MEMS switching membranes, along with prototypes of the building blocks to be embedded in the final module, are designed, optimized and fabricated. The experimental measurements performed on the prototypes of membranes (i.e. micro-switches), attenuation cells, optimized resistors and a phase shifter are compared to FEM-based (Finite Element Method) simulated results. Such comparison validates the simulation approach, in both the electromagnetic and the electro-mechanical domains, by which the proposed module is then designed and optimized in its final layout. To the best of our knowledge, this project is among the first to investigate the development of a monolithic module, entirely based on RF-MEMS passives, implementing both the attenuation and the phase shifting functionalities that can be employed in hybrid beamforming architectures at each antenna element. More in detail, the module features at least 25 attenuation and phase shifting states, from -5.39 dB to -13.51 dB by variable steps, and from 10.59° to 158.46°, respectively. Concerning the SPDT switch, satisfying electrical performances have been demonstrated in terms of return loss (&lt;-10 dB), insertion loss (&lt;-1.2 dB) and isolation (&lt;-25 dB) over the 0–30 GHz interval. Despite their increased complexity, appealing results have marked the proposed attenuator and the phase-shifting cells, whose return and insertion losses are always better than -10 dB and -3 dB, respectively, along the frequency interval of interest. With an overall footprint not exceeding 9.51x3.35 mm2, the designed module effectively combines the miniaturization, broadband, and linear electrical behavior of RF-MEMS, making it a suitable candidate for the MIMO antennas of the current and future telecommunications scenario.