A flexible BIST strategy for SDR transmitters

International audienceSoftware-defined radio (SDR) development aims for increased speed and flexibility. The advent of these system level requirements on the physical layer (PHY) access hardware is leading to more complex architectures, which together with higher levels of integration pose a challenging problem for product testing. For radio units that must be field-upgradeable without specialized equipment, Built-in Self-Test (BIST) schemes are arguably the only way to ensure continued compliance to specifications. In this paper we introduce a loopback RF BIST technique that uses Periodically Nonuniform Sampling (PNS2) of the transmitter (TX) output to evaluate compliance to spectral mask specifications. No significant hardware costs are incurred due to the re-use of available RX resources (I/Q ADCs, DSP, GPP, etc.). Simulation results of an homodyne TX demonstrate that Adjacent Channel Power Ratio (ACPR) can be accurately estimated. Future work will consist in validating our loopback RF BIST architecture on an in-house SDR testbed

Electrostatically-induced modal crosstalk phenomena in resonant MEMS sensors

International audienceThe aim of this paper is to introduce an explanation for the amplitude saturation and inhibition phenomena in resonant MEMS pressure sensors, via the electrostatic coupling of two resonance modes. Our analysis and experimental results reveal that these phenomena may be ubiquitous in electrostatic resonant MEMS sensors

LMS-Based RF BIST Architecture for Multistandard Transmitters

Article accepté pour publicationInternational audienceSoftware defined radios (SDR) platforms are increasingly complex systems which combine great flexibility and high performance. These two characteristics, together with highly integrated architectures make production test a challenging task. In this paper, we introduce an Radio Frequency (RF) Built-in Self-Test (BIST) strategy based on Periodically Nonuniform Sampling of the signal at the output stages of multistandard radios. We leverage the I/Q ADC channels and the DSP resources to extract the bandpass waveform at the output of the power amplifier (PA). Analytic expressions and simulations show that our time-interleaved conversion scheme is sensitive to time-skew. We propose a time-skew estimation technique based on a Least Mean Squares (LMS) algorithm to solve this problem. Simulation results show that we can effectively reconstruct the bandpass signal of the output stage using this architecture, opening the way for a complete RF BIST strategy for multistandard radios

An RF BIST Architecture for Output Stages of Multistandard Radios

Article accepté pour publicationInternational audienceSoftware defined radios (SDR) platforms are in-creasingly complex systems which combine great flexibility and high performance. These two characteristics, together with highly integrated architectures make production test a challenging task. In this paper, we introduce an Radio Frequency (RF) Built-in Self-Test (BIST) strategy based on Periodically Nonuniform Sampling of the signal at the output stages of multistandard radios. We leverage the I/Q ADC channels and the DSP resources to extract the bandpass waveform at the output of the power amplifier (PA). Analytical expressions and simulations show that our time-interleaved conversion scheme is sensitive to time-skew. We show a time-skew estimation technique that allows us to surmount this obstacle. Simulation results show that we can effectively reconstruct the bandpass signal of the output stage using this architecture, opening the way for a complete RF BIST strategy for multistandard radios. Future developments will be focused on an efficient mapping to hardware of our new time-skew estimation for TIADC bandpass conversion

Une sémantique multi-paradigme pour simuler des modèles SysML avec SystemC-AMS

National audienceDans le contexte de la modélisation de systèmes, SysML apparait comme un langage pivot de spécification et de documentation. Ses diagrammes permettent la définition de la structure et du comportement de systèmes. La flexibilité de SysML a pour incon-vénient qu'il n'existe pas de méthode standard pour définir leur sémantique. Ce problème est flagrant dans la conception de systèmes hétérogènes, où différentes sémantiques opéra-tionnelles peuvent être utilisées. Cet article présente une manière de donner une sémantique opérationnelle aux éléments de SysML sous la forme de transformations vers le langage SystemC-AMS, permettant ainsi la simulation de modèles SysML

Enseignement de la microélectronique à Supélec : Une nouvelle pédagogie mise en place en 2012

National audienceLa rentrée 2012 a été le cadre d’une réforme de l’enseignement de l’électronique intégrée au seinde la majeure MNE (Micro et Nano Electronique) à Supélec. Les objectifs étaient de proposer une nouvelleforme d’enseignement pratique au moyen d’un projet long, de regrouper un ensemble de cours dans unensemble cohérent, de faire intervenir tous les enseignants de l’équipe auprès des élèves dès la rentrée, etsurtout de proposer un maximum de pratique aux élèves de manière à remotiver les élèves autour d’unediscipline qui n’est pas toujours très à la mode dans le monde numérique actuel. L’évaluation des élèves aaussi été repensée de manière à sortir les élèves d’un cadre scolaire et les mettre dans la peau d’unresponsable de projet au sein de l’industrie. L’introduction de points de passage formels avec remise derapports et présentation orale permet aux élèves de découvrir la réalité de leur métier de futur ingénieur. Leretour des élèves a montré que ce nouvel enseignement a été très apprécié de l’ensemble des élèves

O Largo da Banana e a presença negra em São Paulo

The Largo da Banana relates to the history of the black population in São Paulo. Acknowledged as one of São Paulo’s “cradle” of samba, samba musicians are its main spokespersons. Largo da Banana used to be located near the former Barra Funda Railway Station. From the first decades to around half the Twentieth century, informal laborers in the railway logistics used to gather together in that space. Within a precarious and unsteady daily life, they used to play samba and tiririca. In the fifties, the municipality built the Pacaembu Viaduct in that area, aiming to extend the homonym avenue beyond the railway road. In the sixties, samba musician Geraldo Filme wrote two songs in which he paid homage to Largo da Banana and regrettedits disappearance after the viaduct’s inauguration. In these and other of his songs, the artist recorded his perceptions on the life conditions of São Paulo’s blacks and samba musicians, their sociabilities, and also the urban changes he witnessed. Considering that his artistic work contributes to enlighten aspects of social reality, I analyze some of his songs to interpret the sociabilities at Largo da Banana, as well as the urban intervention in that location.O Largo da Banana está associado à história da população negra em São Paulo. Reconhecido como um dos “berços” do samba paulista, é sobretudo através dos próprios sambistas que essa história pode hoje ser conhecida. Localizado junto à antiga estação da Barra Funda, desde as primeiras décadas até meados do século passado, aquele espaço concentrou trabalhadores informais vinculados às atividades da ferrovia. Em meio a um cotidiano precário e instável, essa população realizava rodas de samba e de tiririca. Nos anos 1950, foi construído naquele local o Viaduto Pacaembu, que prolongava a avenida homônima para além davia férrea. A partir da década de 1960, o sambista negro Geraldo Filme compôs duas canções em que homenageava o Largo da Banana e lamentava seu desaparecimento após a inauguração do viaduto. Nessas e em outras composições, o artista registrou suas percepções sobre as condições de vida da população negra e sambista na cidade, suas sociabilidades, bem como sobre as transformações urbanas que testemunhou. Considerando que sua obra artística contribui para iluminar aspectos da realidade social, ela é adotada como fonte para analisar as formas de sociabilidade no Largo da Banana e a intervenção urbanística naquele local

Flexible Wideband Radio Transceiver Testing using Non-Uniform Subsampling Demodulation

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Impact of the closed-loop phase shift on the frequency stability of capacitive MEMS oscillators

International audiencePhase noise is a clue performance indicator for MEMS-based resonant sensors. The optimal resolution achievable with these sensors is limited by the close-to-the-carrier phase noise resulting from the modulation of noise sources by the mechanical resonator. In this paper, we focus on the effect of a white noise input source on a one-sided capacitive MEMS resonator. We study how the closed-loop phase shift affects its frequency stability. Our study reveals the existence of optimal points, with phase noise minimization and SNR maximization, which cannot be predicted by a traditional third-order Taylor-Series approach. We reveal that, due to the modulation of the actuation force by the electrostatic nonlinearity, tuning the closed-loop phase shift to improve the oscillator frequency stability is especially relevant

Resonant pull-in of high-Q MEMS oscillators with arbitrary closed-loop phase shift

International audienceIn this article, we develop a simple closed-form expression of the resonant pull-in instability of high-Q MEMS resonators actuated with arbitrary periodic waveforms and arbitrary closed-loop phase shifts. The instability of MEMS oscillators operated under a low bias voltage is shown to be independent of the dimensions and physical properties of the resonator and fully-determined by the quadrature component of the actuation. The results are illustrated on parallel-plate capacitive MEMS actuated with sine-, square- and pulsed-wave voltages. Input-design methods optimizing the pull-in conditions of sensors and switches can be built based on our conclusions