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Abstract

Germanium material is particularly suitable for high frequency applications, especially RF MEMS ones. It may be used not only as sacrificial layers, like previously published in the literature, but also into the elaboration of integrated resistors for serial RF MEMS switches. The compatibility of germanium as resistive material in MEMS has been carried out and led to the successful demonstration of integrated Ge resistors into serial RF MEMS variable capacitors, without any RF perturbations. The compatibility of this layer with the MEMS process has been studied and validated with variable MEMS capacitors employed as demonstrators.

Résumé

L'utilisation de systèmes micro-electro-mécaniques (MEM) dans des applications complexes de communication et notamment pour l'élaboration de tuner d'impédance est prometteuse grâce à leurs nombreux avantages : faible consommation, grande linéarité, faibles pertes, compacité. Néanmoins pour obtenir de telles performances, leur procédé de fabrication nécessite des optimisations spécifiques. La qualité de contact des commutateurs est notamment conditionnée par l'obtention d'une membrane plate et de lignes coplanaires non rugueuses. Les composants obtenus sont alors compatibles avec des applications à la fois de faible et de forte puissance. Ce procédé a été appliqué à la réalisation d'un tuner d'impédance à 20GHz dédié à la mesure de paramètres de bruit, dont les étapes de conception sont décrites dans ce papier.

Abstract

This Letter reports experimental observations regarding the significant changes in the transmission modulus and phase of the propagating microwave signals up to 110 GHz in a micromachined coplanar waveguide supported on a dielectric membrane with a thickness of 1.4 µm filled with a mixture of carbon nanotubes when exposed to nitrogen gas. These large shifts of amplitude and phase of microwave signals due to gas absorption represent the experimental basis on which a miniature wireless gas sensor could be implemented.

Abstract

The attractive advantages of Micro-Electro-Mechanical systems (MEMS) in term of compactness, integrability and reconfigurability promise architecture evolution and performances enhancement of communication applications [1]. Moreover high linearity and isolation, low losses and power consumption are their main driving force compared to active devices. In order to be compatible with packaging process and high power communication systems [2], MEMS switches have to handle temperature stress without strong deformations. It is also a criterion of reliability. In this paper, two capacitive switches topologies shown in Figure 1 are investigated. Two MEMS topologies have been studied and differ from the stiffness of their arms: one is chosen stiffer (switch A) than the other (switch B). A meander has been added on arms of the second structure to enhance the flexibility. The stiffness of this component is divided by a factor 10 compared to the other one. A specific thermal stress protocol has been applied from 20 up to 120°C on both structures. And the evolution of the MEMS air gap and further characteristics have consequently been measured. The main result indicates that a different thermal compensation depending on the stiffness of the MEMS arms and anchorages has been obtained.

Résumé

Lutilisation de systèmes micro-electro-mécaniques (MEM) dans des applications complexes de communication est prometteuse grâce à leurs nombreux avantages : faible consommation, grande linéarité, faibles pertes. Néanmoins pour obtenir de telles performances, leur procédé de fabrication nécessite des optimisations spécifiques. La qualité de contact des commutateurs est notamment conditionnée par lobtention dune membrane plate et de lignes coplanaires non rugueuses. Les composants obtenus sont alors compatibles avec des applications à la fois de faible et de forte puissance. Ensuite, ce procédé est appliqué à la réalisation dun tuner dimpédance à 20GHz dédié à la mesure de paramètres de bruit.

Résumé

Le but de cet article est de présenter la méthodologie développée afin de modéliser un nano-interrupteur à base de nanotubes de carbone. A contrario des MEMS dont l'hypothèse classique de calcul de tension de basculement consiste à considérer une poutre comme une structure suspendue par un ressort [1]. Notre approche considère le système réel : poutre encastrée avec une hypothèse sur la forme de la déflexion de cette poutre. De plus, notre modélisation permet, entre autres, de bien quantifier les phénomènes d'effets de bords qui sont prépondérants dans les systèmes à base de nanotubes de carbone. Enfin nous donnerons des exemples sur l'utilité de nos outils pour la prédiction du comportement d'un nanotube attiré par une force électrostatique.

Abstract

In this letter the authors analyze two configurations of nanoelectromechanical switches, which are working in the microwave and millimeter wave frequency ranges. Metallic nanotubes vertically or horizontally positioned on a propagating high frequency planar waveguide disable or enable the electromagnetic field propagation, whether they are actuated or not by a dc electric field of a few volts. Although the dimensions of metallic nanotubes are very small in comparison with the planar waveguide dimensions and the operating wavelengths, these switches are very efficient and agile.

Abstract

This paper describes the optimized fabrication of capacitive MEM switch dedicated to both low and high power applications. In order to get a good capacitor ratio, the contact quality of the MEM switch has been optimized. Both metal line roughness and membrane flatness have been investigated. Consequently, insertion losses of 0.13dB as well as an isolation of 40dB at 20GHz have been measured. It corresponds to a 47% contact quality, which is equivalent to those obtained in the state of the art with low power level technologies.

Mots-Clés / Keywords

Abstract

This paper presents the design of a high performance and compactness coupler integrated with a 3D technology using BCB (Benzo-Cyclo-Butene) polymer. The main interests of the proposed technology are first the possibility to design multilayer passive devices to achieve high compactness and secondly to be able to monolithically integrate both passive and active circuits as the technological process is fully compatible with ICs. This technology was used to design coupler for which high compactness is reached by applying size reduction to the transmission lines. Electromagnetic simulations have been performed and show excellent performances in terms of amplitude and phase imbalance, isolation and return loss. Several versions of the coupler have been compared to emphasis such performances versus the reduction factor.