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Villeneuve-la-Rivière, France

Croenne C.,Higher Institute of Electronics and Digital Studies | Ponge M.-F.,Higher Institute of Electronics and Digital Studies | Dubus B.,Higher Institute of Electronics and Digital Studies | Granger C.,Higher Institute of Electronics and Digital Studies | And 6 more authors.
Journal of the Acoustical Society of America | Year: 2016

Phononic crystals made of piezoelectric composites with 1-3 connectivity are studied theoretically and experimentally. It is shown that they present Bragg band gaps that depend on the periodic electrical boundary conditions. These structures have improved properties compared to phononic crystals composed of bulk piezoelectric elements, especially the existence of larger band gaps and the fact that they do not require severe constraints on their aspect ratios. Experimental results present an overall agreement with the theoretical predictions and clearly show that the pass bands and stop bands of the device under study are easily tunable by only changing the electrical boundary conditions applied on each piezocomposite layer. © 2016 Acoustical Society of America. Source

Iskander R.,University Pierre and Marie Curie | Louerat M.-M.,University Pierre and Marie Curie | Kaiser A.,Institute dElectronique
Integration, the VLSI Journal | Year: 2013

A hierarchical sizing and biasing methodology for analog firm intellectual properties (IPs) is presented. An analog firm IP designates an unsized transistor netlist of an analog circuit. The methodology sizes and biases an analog firm IP by automatically generating suitable sizing procedures. The generated procedures respect topology constraints, designer's hypotheses and design constraints. The procedures are represented using dependency graphs. The methodology deals with different aspects of analog design problems such as MOS inversion level control, insufficient or excess design parameters, systematic offset and negative-feedback. Its application in both fields of analog synthesis and simulation is outlined. The proposed methodology has been successfully used to size, bias and analyze two analog IPs: a single-ended two-stage operational amplifier and a fully differential transconductor. This is performed using 130 nm CMOS technology with VDD=1.2V. The results prove the effectiveness and precision of the proposed methodology. © 2012 Elsevier B.V. Source

Swinteck N.,University of Arizona | Robillard J.-F.,University of Arizona | Bringuier S.,University of Arizona | Bucay J.,University of Arizona | And 4 more authors.
Applied Physics Letters | Year: 2011

We report on a phononic crystal (PC) consisting of a square array of cylindrical polyvinylchloride inclusions in air that can be used to control the relative phase of two incident acoustic waves with different incident angles. The phase shift between waves propagating through the crystal depends on the angle of incidence of the incoming waves and the PC length. The behavior of the PC is analyzed using the finite-difference-time-domain method. The band structure and equifrequency contours calculated via the plane wave expansion method show that the distinctive phase controlling properties are attributed to noncollinear wave and group velocity vectors in the PC as well as the degree of refraction. © 2011 American Institute of Physics. Source

Goh W.H.,Georgia Institute of Technology | Patriarche G.,CNRS Optic of Semiconductor nanoStructures Group | Bonanno P.L.,Georgia Institute of Technology | Gautier S.,University Of Metz Et Suplec | And 11 more authors.
Journal of Crystal Growth | Year: 2011

Nanodots, nanowires, and semi-polar quantum well structures of GaN-based material have been grown by nano-selective area growth (NSAG). The growth evolution of the nanostructure has been studied. Cross-sectional transmission electron microscopy (TEM) shows that the nanostructures are free of threading dislocations. The growth of AlGaN/GaN layers is uniform and shows sharp interfaces between the AlGaN and GaN epilayers. AlGaN nanodots/nanowires, which are formed at the apexes of the nano-pyramids/nano-ridges, are found to be homogeneous in size and to have a higher aluminum mole fraction than the surrounding material. In contrast, the InGaN/GaN growth shows no quantum dots at the apexes of the nanostructures. We found that the growth facets of different Miller's indices are formed on the InGaN/GaN nano-ridges. Energy dispersive X-ray spectroscopy (EDX) shows higher indium incorporation at the intersection of the growth facets. Cathodoluminescence measurements show enhanced luminescence intensity from InGaN multi-quantum wells (MQWs) grown on the nanostructure compared to that from InGaN MQWs grown on an unpatterned area. © 2010 Elsevier B.V. Source

Hochedez J.-F.,French National Center for Scientific Research | Soltani A.,Institute dElectronique | Bourzgui N.,Institute dElectronique | Saito T.,Tohoku Institute of Technology | And 4 more authors.
Experimental Astronomy | Year: 2015

We present a long-term assessment of the radiometric calibration and degradation of the Large Yield Radiometer (LYRA), which has been on orbit since 2009. LYRA is an ultraviolet (UV) solar radiometer and is the first space experiment using aboard a pioneering diamond detector technology. We show that LYRA has degraded after the commissioning phase but is still exploitable scientifically after almost 5 years on orbit thanks to its redundancy design and calibration strategy correcting for instrument degradation. We focus on the inflight detector’s calibration and show that diamond photodetectors have not degraded while silicon reference photodiodes that are even less exposed to the Sun show an increase of their dark current and a decrease of their photoresponse. © 2015, The Author(s). Source

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