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Abstract

A nonlinear noise model of a SiGe bipolar transistor is presented. This model includes a nonlinear noise source and is able to predict the noise conversion phenomena in circuits using this transistor such as oscillator phase noise. It is based on two main low frequency noise sources, which are extracted thanks to noise measurements under large RF signal superposition. An original low phase noise X band amplifier is also presented. This amplifier features a phase noise performance of 160 dBrad2· Hz1 at 10 kHz offset frequency together with a low DC power consumption of 50 mW.

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Abstract

Optical devices are more and more involved in time and frequency applications. They may be used for frequency reference signal distribution in a system, taking benefit of the low losses of the optical fibers, and of their small size and their immunity to electrical parasitic signals. They may also be used to realize high quality resonators and delay lines, leading to equivalent Q factors which are difficult to reach with classical RF or microwave techniques. It is important to be able to compute microwave-optical links and systems. Specially, phase noise system. This paper gives an overview of various approaches which can be used to describe an optical device with an equivalent electrical circuit, or simply with a mathematical model, and to include this model in the chosen CAD tool. We have worked with Agilent ADS microwave simulation software.

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Abstract

The use of optical resonators for microwave filtering is discussed. Several measurement benches, allowing the test of the optical and optical-microwave properties of high Q optical WGM resonators or optical fiber loop resonators, have been set-up. This paper gives an overview of all these measurement benches, together with a preliminary result on an RF high quality factor filter realized using a small length fiber loop.

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A test set-up for the characterization of microwave BAW resonators driven into nonlinear regime is presented. In this set-up, a network analyser is coupled to a spectrum analyser, in order to measure simultaneously the resonant frequencies and the nonlinear behaviour (harmonic generation). A power amplifier (5 W) is used at the network analyser output, because this nonlinear behaviour can only be observed at high power. Finally, the set-up is used to evaluate these properties on a set of SMR resonators.

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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.

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Abstract

The evolution of spectrally pure microwave sources is described, together with the problem of modeling the spectral shape of these signals. The noise sources interaction with the intrinsic nonlinear behavior of the oscillator is pointed out, and various solutions are proposed. Original techniques are shown to investigate on the phase noise modeling directly at the transistor level. Then, the problem of noise in some new approaches for frequency generation, in which other noise sources than the transistor noise contributes to the oscillator noise, is described.

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Bias electrode DC drift of LiNbO3 optical modulators becomes a critical problem when these devices operate over a long time period. This article presents a novel system of DC drift compensation for optical microwave transmissions using optical carrier suppression technique. In our case, such a system is dedicated to the optical distribution of high spectral purity microwave signals in future satellite payloads.

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Résumé

Ce papier rapporte les principaux résultats de la comparaison en mesures de densité spectrales de bruit de phase réalisée d'octobre 2005 à décembre 2006 sur deux paires d'oscillateurs à 5 et 100 MHz ainsi qu'un ORD à 3.5 GHz. Il ne s'agit pas tant de comparer les performances des oscillateurs, mais bien de comparer et évaluer les incertitudes et la résolution des bancs ainsi que la reproductibilité des mesures. Le but n'est pas de faire une compétition entre les différents moyens de mesures existants mais plutôt de raccorder plusieurs systèmes afin d'améliorer la confiance que l'on peut avoir dans les mesures de bruit de phase.

Abstract

This paper reports main results of the phase noise comparison that has been performed between october 2005 and december 2006, using two oscillators at 5 and 100 MHz and un DRO at 3.5 GHz. The problem is not to compare the performances of several oscillators, but to compare and to make an evaluation of the uncertainties, and of course the resolution and the reproducibility of the measurements. This comparison allow us to determine the ability to get various systems traceable together in order to increase the trust that one can have in phase noise measurements.

Résumé

Ce papier présente une modélisation non linéaire en bruit d'un transistor bipolaire SiGe. Limplémentation de sources de bruit non linéaires dans le modèle du transistor est décrite. Ce modèle sappuie sur lobservation dun comportement non linéaire de la source de bruit en tension extrinsèque en parallèle à la jonction base émetteur. La validation de ce modèle est effectuée grâce à la mesure du bruit de phase du transistor étudié dans différentes configurations de polarisation et de puissance. Ce modèle a permis la conception d'un amplificateur à faible bruit de phase pour la réalisation d'un oscillateur à très haute pureté spectrale fonctionnant à 10 GHz. Cet amplificateur à deux étages a été conçu en s'appuyant sur le modèle précédent. Les performances obtenues sont d'un très bon niveau, en effet le gain est égal à 8.2 dB et le bruit de phase à 100 kHz de la porteuse de -165dBrad2.Hz-1.

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