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Résumé

Les performances des résonateurs hyperfréquences en termes de facteurs de qualité sont actuellement limitées. Une solution consiste à transporter les hyperfréquences sur un support différent, en l'occurrence une onde optique. Les résonateurs optiques deviennent alors des objets très intéressants pour l'élaboration de nouveaux résonateurs hyperfréquences plus performants. Des facteurs de qualité optiques supérieurs à 109 peuvent être atteints avec des résonateurs fibrés ou à modes de galerie, par exemple, donnant ainsi accès à des facteurs de qualité supérieurs à 105 à 20 GHz. Nous présentons donc notre étude de différents résonateurs optiques (résonateurs à modes de galerie et boucles de fibre) destinés à la stabilisation d'oscillateurs hyperfréquences autour de 10 GHz, ainsi que leur application à la réalisation d'un oscillateur opto-micro-onde à cette fréquence.

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Abstract

Different high-Q optical resonators are presented in this communication. Our aim is to use them to develop compact high performances microwave oscillators. The optical quality factor of a quartz disk used as a whispering gallery modes resonator has been measured to be higher than 10^9. We also investigate the potentialities of high-Q fibre ring resonators. The performances of an optoelectronic oscillator at 10 GHz based on such a passive fibre ring resonator are presented here.

Abstract

A low phase noise and wide-bandwidth frequency divider has been developed in a 0.25 ¼m SiGe:C process. This paper discusses the BiCMOS design improvements used for ultra low phase noise applications like on-chip phase-noise measurement circuit. From a singleended signal provided by a local oscillator LO, the widebandwidth frequency divider circuit generates accurate quadrature signals. For the full 1kHz-5.5 GHz input frequency range, the frequency divider achieves an output quadrature error less than ±1°. This paper presents a novel architecture designed for improving phase noise and exhibits a measured residual phase noise of -164 dBc/Hz @ 100 kHz with a 3.5 GHz input frequency.

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The design and realization of an ultra-low noise operational amplifier is presented. Its applications are integrated low-frequency noise measurements in electronic devices and onchip phase-noise measurement circuit. This paper discusses the SiGe:C BiCMOS 0.25 ¼m design improvements used for low noise applications. The proposed three-stage operational amplifier uses parallel bipolar transistor connection as input differential pair for low noise behavior. This operational amplifier provides both low noise and high gain performances. This operational amplifier has an area of only 660×250 ¼m2 with an equivalent input noise floor of only 1.1 nV/Hz square root at 10 kHz. The measured noise characteristics (versus total power consumption) are better than those of most operational amplifiers commonly adopted in low-frequency noise measurements. The AC gain is 83 dB and the unity gain bandwidth is 210 MHz, with a total current consumption of 18 mA at 2.5 V supply voltage.

Abstract

The potential of optical fiber ring resonators for RF or microwave signals filtering on optical carriers is demonstrated on a short length high Q resonator. The problem of the frequency shift due to the resonator self heating with the optical power is solved thanks to a Pound-Drever feedback loop. A multi frequency RF filter is obtained, with a frequency step of 205 MHz between resonances, and a 3 dB bandwidth of 2.4 MHz. This corresponds to the computed optical resonator 3 dB bandwidth, and thus represents an efficient technique for the measurement of ultra high Q optical resonators. In the field of microwave applications, the equivalent Q factor obtained is particularly interesting in the upper microwave range.

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A technique is described to implement a microwave filtering approach based on optical resonators. This technique involves the laser stabilization onto a resonator mode, and the use of the two lateral sidemodes for RF or microwave filtering. The Q enhancement compared to the classical non-coherent optical delay line technique is high, and the equivalent microwave Q overcome the best microwave resonators, at least in the upper microwave range.

Abstract

Optical techniques for microwave oscillators stabilization or microwave sources phase noise measurement are discussed. The advantage in terms of Q factor of optical resonant devices goes with increased difficulties in the system stabilization. System modelling is also complex, because of the interaction of noise sources around three different frequencies : optical, microwave and baseband.

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