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Abstract

This paper addresses the design and the realization of tunable bandstop filters using MEMS (Micro-Electro-Mechanical-Systems) technology for millimeter wave applications. In order to design bandstop tunable MEMS filters, three new topologies are presented. The presented measurement and simulation results validate the proposed topologies. The tunable behavior is achieved using MEMS switches. These switches, based on original topology of Two Cantilever Shunt Switch (TCSS), have a typical shunt switch behavior and intrinsic low actuation voltage. The overall structures, including TCSS, have been manufactured using dielectric membrane, in order to minimize the insertion losses.

Abstract

This paper reports on the investigation of failure mechanisms of AlN-based capacitive RF MEMS switches. Electrostatic Discharge (ESD) experiments have been carried out by means of a Transmission Line Pulsing (TLP) technique. It has been observed that ESD stresses create some electric arcs and the degradations have been observed and analyzed. Microwave measurements have shown that ESD stress impacts the quality of the capacitive contact.

Mots-Clés / Keywords

Abstract

A nonlinear noise model of a SiGe bipolar transistor is presented. This model includes nonlinear noise sources and is able to predict the noise conversion phenomena in circuits using this transistor and as the phse noise of an oscillator. It is based on two main low frequency noise sources, which are extracted thanks to noise measurements under large RF signal superposition. The model is compared to the experiment thanks to residual phase noise data at different RF power level.

Mots-Clés / Keywords

Abstract

Wide bandgap devices such as AlGaN/GaN High Electron Mobility Transistors (HEMT) grown on silicon carbide (SiC) substrate are investigated. Low frequency noise (LFN) measurements have been carried out to evaluate the structural perfection of dual gated HEMT devices featuring 0.25x2x75µm² gate area: generation-recombination (GR) processes are evidenced. Two sets of GR-bulges related respectively to AlGaN/GaN interface and quantum well are identified. Each GR-bulge is composed of two GR centers. The devices are then characterized in a temperature controlled oven, and these GR centers are extracted from LFN spectra versus temperature. Activation energies of the defects located at the AlGaN/GaN interface are measured at 0.38±0.05eV and 0.21±0.05eV using Arrhenius plots under saturated biasing conditions. Equivalent activation energies are extracted under ohmic biasing conditions. These results are compared with SIMS measurements, using the deuterium in diffusion condition as a probe to integrally explore the presence of defects throughout the AlGaN-GaN HEMT structure. Large concentrations of deuterium (more than 10E20 D concentration per cm3) are measured at the AlGaN/GaN interface and in the 2DEG layer, thus proving the presence of numerous vacations at the AlGaN/GaN interface as well as in the 2DEG. From the confrontation with previously published results, the defects might be assigned to the nitrogen vacancy and to MgGa-VN complexes.

Mots-Clés / Keywords

Abstract

The design and realisation of original millimetre-wave tunable bandstop filters using MEMS (micro-electro-mechanical-systems) technology for millimetre-wave applications is presented. The tunable behaviour is achieved by using MEMS switches. The overall structures, including the MEMS switches, have been manufactured using dielectric membrane in order to minimise the dielectric losses. Experimental validations are reported and validate the proposed topology: the bandstop frequency is shifted by approximately 3.5 GHz in V-band when the switches are actuated.

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.

Résumé

Les intérêts de recherche exposés dans cette présentation écrite portent sur la fiabilité et l'analyse de défaillance des microcommutateurs MEMS RF capacitifs à base de Nitrure d'Aluminium (AlN). Ce sujet s'étend sur deux axes, tout d'abord le chargement du diélectrique a été expérimenté à l'aide de contraintes DC qui se traduit par un décalage de la tension d'activation du dispositif si on observe l'évolution du paramètre S21 en fonction de la tension de polarisation. La cinétique de ce décalage a été calculée et reportée sur une figure de mérite incluant d'autres résultats déjà publiés. Il sera montré que l'AlN a une meilleure propriété de chargement que le nitrure de silicium (Si3N4). Ensuite, les premières expériences de décharge électrostatique (ESD) à l'aide d'une méthode dite TLP (Transmission Line Pulse) ont montré leur comportement face aux phénomènes disruptifs produits pour des niveaux d'impulsions assez élevés. Des zones de fusion sur la membrane et sur le diélectrique sont visibles après l'apparition d'arcs électriques et ces dégradations se vérifient également sur les caractéristiques micro-ondes.