Integrated Circuit and System Design for Cognitive Radio and Ultra-Low Power Applications

The ubiquitous presence of wireless and battery-powered devices is an inseparable and invincible feature of our modern life. Meanwhile, the spectrum aggregation, and limited battery capacity of handheld devices challenge the exploding demand and growth of such radio systems. In this work, we try to present two separate solutions for each case; an ultra-wideband (UWB) receiver for Cognitive Radio (CR) applications to deal with spectrum aggregation, and an ultra-low power (ULP) receiver to enhance battery life of handheld wireless devices. Limited linearity and LO harmonics mixing are two major issues that ultra-wideband receivers, and CR in particular, are dealing with. Direct conversion schemes, based on current-driven passive mixers, have shown to improve the linearity, but unable to resolve LO harmonic mixing problem. They are usually limited to 3rd, and 5th harmonics rejection or require very complex and power hungry circuitry for higher number of harmonics. This work presents a heterodyne up-down conversion scheme in 180 nm CMOS technology for CR applications (54-862 MHz band) that mitigates the harmonic mixing issue for all the harmonics, while by employing an active feedback loop, a comparable to the state-of-the art IIP3 of better than +10 dBm is achieved. Measurements show an average NF of 7.5 dB when the active feedback loop is off (i.e. in the absence of destructive interference), and 15.5 dB when the feedback loop is active and a 0 dBm interferer is applied, respectively. Also, the second part of this work presents an ultra-low power super-regenerative receiver (SRR) suitable for OOK modulation and provides analytical insight into its design procedure. The receiver is fabricated in 40 nm CMOS technology and operates in the ISM band of 902-928 MHz. Binary search algorithm through Successive Approximation Register (SAR) architecture is being exploited to calibrate the internally generated quench signal and the working frequency of the receiver. Employing an on-chip inductor and a single-ended to differential architecture for the input amplifier has made the receiver fully integrable, eliminating the need for external components. A power consumption of 320 µW from a 0.65 V supply results in an excellent energy efficiency of 80 pJ/b at 4 Mb/s data rate. The receiver also employs an ADC that enables soft-decisioning and a convenient sensitivity-data rate trade-off, achieving sensitivity of -86.5, and -101.5 dBm at 1000 and 31.25 kbps data rate, respectivel

Grouper des textes à l’école élémentaire

Agrupar textos” en la escuela elemental evoca lo que se hacía antes. ¿Por qué no? Después de decenas de años, tanto los manuales de lectura como los de francés (de manera integrada), ofrecen una organización temática conformada por: fragmentos de textos agrupados bajo la consigna de palabrastemas (el mar, el otoño…). Tipos y géneros de textos se mezclan sin que las nociones y los problemas particulares de lectura y escritura allí implicados se articulen bajo un campo temático. Esta aproximación permanece implícita y nada se problematiza, ya que todo parece ir bien para los alumnos y el maestro, la lectura de cada texto queda encerrada en ella misma

Étude des rapports anatomiques entre rachis cervical et base du crâne sur une série de têtes de momies égyptiennes (Collection du Musée des Confluences de Lyon)

International audienc

II. — Informations et publications

Griselli Annamaria, Perrot M.-J., Poujol Geneviève, Kovacs Annie. II. — Informations et publications . In: Revue française de pédagogie, volume 43, 1978. pp. 131-148

II. — Informations et publications

Griselli Annamaria, Perrot M.-J., Poujol Geneviève, Kovacs Annie. II. — Informations et publications . In: Revue française de pédagogie, volume 43, 1978. pp. 131-148

The Concepts of Seed Germination Rate and Germinability: A Re-Evaluation for Cool-Season Grasses

Temperature is one the most influential environmental factors for the germination and establishment of grass species. The specific objective of this study was to determine the effects of low constant temperature on the time needed to express the full germination capacity of nondormant seedlots. Fifteen accessions, comprising seven of Lolium perenne L., three of Festuca arundinacea Schreb., three of Dactylis glomerata L. and two of Triticum aestivum L., were evaluated at constant temperatures of 5 and 21 °C. As expected, the germination rates were faster at 21 °C than at 5 °C. Indeed, at 5 °C seeds needed up to twenty-one times longer to reach the maximum germination than when tested at 21 °C. The genotypic variability found for the ratio of germination rates between the two temperatures (i.e., germination rate at 5 °C/germination rate at 21 °C) was much more variable than what is found in the literature for perennial cool-season grasses. On the other hand, in most cases, no significant differences were observed in the germinability (the capacity to germinate) response to 5 °C and 21 °C. Within the four species, twelve of the fifteen studied accessions expressed the same germinability at 5 °C and 21 °C, when given enough time. Only three accessions had final germination percentages higher at 21 °C than at 5 °C. Our results suggest that, in general, nondormant seeds at low temperatures germinate as well as nondormant seeds at near-optimal temperatures, provided they have enough time to express their germination capacity. These findings cast doubts on the validity of conclusions drawn in many studies where germination experiments were performed for a period insufficient to obtain full germination at low temperatures. Another major finding in this work concerns the risk of wrongly estimating germinability at low temperatures

Objets et insignes du pouvoir

La représentation du pouvoir, qu’il soit politique ou religieux, est matérialisée par des objets : sièges, vêtements, attributs... À l’aide d’exemples significatifs des grandes civilisations passées et actuelles, l’étude s’attachera à en cerner l’origine, la signification et l’usage. Colloque organisé en collaboration avec l’Institut des images. Consulter le programme complet du colloque. Ce colloque est lié au programme de recherche du Centre de recherche du château de Versailles intitulé Pouvoir et Histoire en Europe du XVe siècle au XVIIIe siècle : textes, images et légitimation politique (2007-2010). Douze communications sur vingt-et-une sont publiées ici en texte intégral. Les textes ont été mis en ligne entre 2007 et 2012. The representation of power, whether political or religious, is materialized by objects, such as chairs, clothing and attributes. Drawing on significant examples from great civilizations past and present, this study endeavours to identify these objects’ origin, meaning and use. This symposium was organized in collaboration with the Institut des Images. See the complete programme of the symposium. This symposium is related to the Centre de recherche du château de Versailles' research programme Pouvoir et Histoire en Europe du XVe siècle au XVIIIe siècle : textes, images et légitimation politique (2007-2010). Twelve of the twenty-one conference papers are published here in full text. The papers have been published between 2007 and 2012