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Advances in wireless technology have recently led to the potential for higher data rates and greater functionality. Wireless home and business networks and 3G and 4G cellular phone systems are promising technologies striving for market acceptance, requiring low-cost, low-power, and compact solutions. One approach to meet these demands is system-on-a-chip (SoC) integration, where RF/analog and digital circuitry reside on the same chip, creating a mixed-signal environment. Concurrently, there is tremendous incentive to utilize Si-based technologies to leverage existing fabrication and design infrastructure and the corresponding economies of scale. While the SoC approach is attractive, it presents major challenges for circuit designers, particularly in the design of monolithic voltage controlled oscillators (VCOs). VCOs are important components in the up or downconversion of RF signals in wireless transceivers. VCOs must have very low phase noise and spurious emissions, and be extremely power efficient to meet system requirements. To meet these specifications, VCOs require high-quality factor (Q) tank circuits and reduction of noise from active devices; however, the lack of high-quality monolithic inductors, along with low noise transistors in traditional Si technologies, has been a limiting factor. This thesis presents the design, characterization, and comparison of three monolithic 3-4 GHz VCOs and an integrated 5-6 GHz VCO with tunable polyphase outputs. Each VCO is designed around a differential -G_{M} core with an LC tank circuit. The circuits exploit two Si-based device technologies: Silicon Germanium (SiGe) Heterojunction Bipolar Transistors (HBTs) for a cross-coupled collectors circuit and Graded-Channel MOS (GC-MOS) transistors for a complementary (CMOS) implementation. The circuits were fabricated using the Motorola 0.4 μm CDR1 SiGe BiCMOS process, which consists of four interconnected metal layers and a thick copper (10 μm) metal bump layer for improved inductive components. The VCO implementations are targeted to meet the stringent phase noise specifications for the GSM/EGSM 3G cellular standard. The specifications state that the VCO output cannot exceed -162 dBc/Hz sideband noise at 20 MHz offset from the carrier. Simultaneously, oscillators must be designed to address other system level effects, such as feed-through of the local oscillator (LO). LO feed-through directly results in self-mixing in direct conversion receivers, which gives rise to unwanted corrupting DC offsets. Therefore, a system-level strategy is employed to avoid such issues. For example, multiplying the oscillator frequency by two or four times can help avoid self-mixing during downconversion by moving the LO out of the bandwidth of the RF front-end. Meanwhile, direct conversion or low-IF (intermediate frequency) receiver architectures utilize in-phase and quadrature (I/Q) downconversion signal recovery and image rejection. Any imbalance between the I and Q channels can result in an increase in bit-error-rate (BER) and/or decrease in the image rejection ratio (IRR). To compensate for such an imbalance, an integrated tunable polyphase filter is implemented with a VCO. Control voltages between the differential I and Q channels can be individually controlled to help compensate for I/Q mismatches. This thesis includes an introduction to design flow and layout strategies for oscillator implementations. A detailed comparison of the advantages and disadvantages of the SiGe HBTs and GC-MOS device in 3-4 GHz VCOs is presented. In addition, an overview of full-wave electromagnetic characterization of differential dual inductors is given. The oscillators are characterized for tuning range, output power, and phase noise. Finally, new measurement techniques for the 5-6 GHz VCO with a tunable polyphase filter are explored. A comparison between the time and frequency approaches is also offered. / Master of Science

This thesis focuses on analyzing the synchronization of time delays between mutually coupled phase-locked loops (PLLs) in a flat hierarchy. Mutual synchronization refers to decentralized synchronization where there is no primary or secondary unit or control source. Consequently, it is an inherently self-organizing system in which each unit has equal rights, making it a democratic system. In this research, a dynamic nonlinear time-domain model is used to describe mutually delayed coupled oscillators. The predictions of this model are evaluated against experimental measurements. The time-domain model is based on the Kuramoto model. The Kuramoto model describes a network of coupled oscillators. As a first impression, this Kuramoto model is first analyzed for understanding of the effects of time delays between oscillators. The time domain model is based on a conventional PLL architecture modified to allow mutual coupling. The modifications include a circuit section that sums and weights all incoming phase differences. Overall, the measured results of this research study are in good agreement with the theoretical predictions of the time-domain model. The analysis allows the identification of the transient dynamics and the mechanisms that lead to mutual coupling and the formation of synchronized states through self-organized synchronization. The results show that the mutual coupling can self-organize its dynamics to synchronize even at time delays where the phenomenon of multistability of synchronized states occurs. A critical time delay beyond which a stable synchronized state cannot be achieved has been identified. The work also analyzes the dynamics and noise of synchronized states and finds that the dynamics near a synchronized state are correlated due to mutual coupling, leading to a reduction in noise. The noise correlation is affected by the direction of coupling, the number of nodes in the network, and the network topology. An improvement in phase noise of up to 14.42 dBc/Hz at 100 kHz offset from the carrier and 49.47ns delay was achieved using all-to-all coupling with four nodes. Furthermore, the hybrid approach, the combination of hierarchical and self-organizing synchronization architectures, is investigated. The dissertation presents an experimental study to understand how this affects a network of mutually delayed delay-coupled oscillators and whether the network of mutually coupled nodes can be abstracted as a secondary oscillator. A range in which the mutually delay-coupled network can be successfully synchronized by an external reference oscillator, depending on the synchronized state, is identified. In summary, this thesis provides valuable insights into the properties of mutually delay-coupled PLLs and their synchronization in flat hierarchies, and contributes to the understanding, design, and optimization of more practical networks of mutually delayed PLLs.:Abstract/Zusammenfassung Symbols and Abbreviations Previous Publications 1 Introduction 1.1 Classifications of Synchronization 1.2 A Historical Perspective on Mutual Synchronization 1.3 Extending the Understanding of Mutual Synchronization 1.4 Definitions and Methodologies 2 Model of Networks of Mutually Coupled PLLs 2.1 Coupled Oscillators – Kuramoto Model 2.1.1 Consequences of a Time Delay between Oscillators 2.1.2 Arbitrary Time Delays between Oscillators 2.2 Time-Domain Model of Delay-Coupled PLLs 2.2.1 Phase Detection 2.2.2 Loop-Filter 2.2.3 Voltage Controlled Oscillator 2.3 Prediction and Stability Analysis of Synchronized States 2.3.1 Assessing the Linear Stability of Synchronized States 2.3.2 Stability Consideration for Two Identical PLL Nodes 2.3.3 The Notion of Mode Locking 2.3.4 Effects of Heterogeneity on Synchronized States 2.4 Dynamics and Noise in Synchronized States 2.4.1 Gain and Phase Margin of a PLL Node 2.4.2 Phase Noise 2.5 Key Findings of the Theoretical Model 3 Design of Phase-Locked-Loops for Mutual Synchronization 3.1 PLL Nodes Dedicated for Mutual Synchronization 3.1.1 Phase Detection Circuitry 3.1.2 Adder Chain 3.2 Additional Circuitry for Implementing a Time Delay 4 Experimental Analysis of Mutually Time-Delayed Coupled PLLs 4.1 Synchronized States Including Oscillator Nonlinearity 4.2 Stability of Multistable Synchronized States 4.3 Critical Time Delay Between Two Coupled Nodes 4.4 Combining Hierarchical and Flat Synchronization Concepts 4.4.1 Entrainment of a Chain Network Topology 4.4.2 Entrainment of a Ring Network Topology 4.5 Heterogeneous Time Delays between Coupled PLLs 4.6 Phase Noise Analysis of Time Delay Coupled PLLs 4.6.1 Phase Noise for Two Mutually Coupled Nodes 4.6.2 The Impact of Coupling Directionality 4.6.3 Long Term Frequency Stability 4.6.4 Effect of Time Delay on Phase Noise 4.6.5 Network Topology Dependency on Phase Noise 5 Conclusion and Future Prospects Bibliography Own Publications – Periodicals Own Publications – Conference Proceedings Co-Authored Publications Other References List of Figures List of Tables Acknowledgement Curriculum Vitae / Diese Arbeit befasst sich mit der Analyse der Auswirkungen von Zeitverzögerungen auf die Synchronisation von gegenseitig gekoppelten Phasenregelschleifen (engl. phase-locked loop (PLL)) in einer flachen Hierarchie. Gegenseitige Synchronisation bezieht sich auf eine dezentrale Synchronisation, bei der es keine primäre oder sekundäre Einheit oder Steuerquelle gibt. Folglich ist es ein inhärent selbstorganisierendes System, in dem jede Einheit gleichberechtigt ist, was es zu einem demokratischen System macht. Für die Untersuchung wird ein dynamisches nichtlineares Zeitbereichsmodell verwendet, um gegenseitig verzögert gekoppelte Oszillatoren zu modellieren und die Vorhersagen dieses Modells anhand experimenteller Messungen zu bewerten. Dieses Zeitbereichsmodell basiert auf dem sogenannten Kuramoto-Modell, das ein Netzwerk gekoppelter Oszillatoren beschreibt. Um einen ersten Eindruck zu erhalten, wird zunächst dieses Kuramoto-Modell analysiert, um die Auswirkungen von Zeitverzögerungen zwischen den Oszillatoren zu verstehen. Das Zeitbereichsmodell basiert auf einer konventionellen PLL-Architektur, die modifiziert wurde, um eine gegenseitige Kopplung zu ermöglichen. Die Modifikationen beinhalten einen Schaltungsteil, der alle eingehenden Phasendifferenzen summiert und gewichtet. Die gemessenen Ergebnisse dieser Untersuchung stimmen insgesamt gut mit den theoretischen Vorhersagen des Zeitbereichsmodells überein. Die Analyse erlaubt es, die transiente Dynamik und die Mechanismen zu identifizieren, die zur gegenseitigen Synchronisation und zur Bildung synchronisierter Zustände durch selbstorganisierte Synchronisation führen. Die Ergebnisse zeigen, dass selbst bei Zeitverzögerungen, bei denen das Phänomen der Multistabilität synchronisierter Zustände auftritt, die gegenseitige Kopplung ihre Dynamik selbst organisieren kann, um sich zu synchronisieren. Die Untersuchung identifizierte eine kritische Zeitverzögerung, bei der kein stabiler synchronisierter Zustand erreicht werden kann. Die Arbeit analysiert auch die Dynamik und das Rauschen von synchronisierten Zuständen und stellt fest, dass die Dynamik in der Nähe eines synchronisierten Zustands aufgrund der gegenseitigen Kopplung korreliert ist, was zu einer Reduktion des Rauschens führt. Die Richtung der Kopplung und die Anzahl der Knoten im Netzwerk sowie die Netzwerktopologie beeinflussen die Korrelation des Rauschens. Eine Verbesserung des Phasenrauschens von bis zu 14.42 dBc/Hz bei einem Versatz von 100 kHz zum Träger und einer Verzögerung von 49.47 ns wurde durch eine globalen oder All-to-All-Kopplung mit vier Knoten erreicht. Des Weiteren wird der hybride Ansatz, die Kombination von hierarchischen und selbstorganisierenden Synchronisationsarchitekturen, untersucht. Die Arbeit präsentiert eine experimentelle Studie, um zu verstehen, wie dies ein Netzwerk von gegenseitig verzögert gekoppelten Oszillatoren beeinflusst und ob das Netzwerk von gegenseitig gekoppelten Knoten als sekundärer Oszillator abstrahiert werden kann. Dabei wird eine vom synchronisierten Zustand abhängige Domäne identifiziert, in der das wechselseitig gekoppelte Netzwerk durch einen externen Referenzoszillator erfolgreich synchronisiert werden kann. Insgesamt liefert diese wissenschaftliche Arbeit wertvolle Erkenntnisse über die Eigenschaften von gegenseitig verzögerungsgekoppelten PLLs und deren Synchronisation in einer flachen Hierarchie und trägt zum Verständnis, zum Entwurf und zur Optimierung von praktisch realisierten Netzwerken gegenseitig verzögerungsgekoppelter PLLs bei.:Abstract/Zusammenfassung Symbols and Abbreviations Previous Publications 1 Introduction 1.1 Classifications of Synchronization 1.2 A Historical Perspective on Mutual Synchronization 1.3 Extending the Understanding of Mutual Synchronization 1.4 Definitions and Methodologies 2 Model of Networks of Mutually Coupled PLLs 2.1 Coupled Oscillators – Kuramoto Model 2.1.1 Consequences of a Time Delay between Oscillators 2.1.2 Arbitrary Time Delays between Oscillators 2.2 Time-Domain Model of Delay-Coupled PLLs 2.2.1 Phase Detection 2.2.2 Loop-Filter 2.2.3 Voltage Controlled Oscillator 2.3 Prediction and Stability Analysis of Synchronized States 2.3.1 Assessing the Linear Stability of Synchronized States 2.3.2 Stability Consideration for Two Identical PLL Nodes 2.3.3 The Notion of Mode Locking 2.3.4 Effects of Heterogeneity on Synchronized States 2.4 Dynamics and Noise in Synchronized States 2.4.1 Gain and Phase Margin of a PLL Node 2.4.2 Phase Noise 2.5 Key Findings of the Theoretical Model 3 Design of Phase-Locked-Loops for Mutual Synchronization 3.1 PLL Nodes Dedicated for Mutual Synchronization 3.1.1 Phase Detection Circuitry 3.1.2 Adder Chain 3.2 Additional Circuitry for Implementing a Time Delay 4 Experimental Analysis of Mutually Time-Delayed Coupled PLLs 4.1 Synchronized States Including Oscillator Nonlinearity 4.2 Stability of Multistable Synchronized States 4.3 Critical Time Delay Between Two Coupled Nodes 4.4 Combining Hierarchical and Flat Synchronization Concepts 4.4.1 Entrainment of a Chain Network Topology 4.4.2 Entrainment of a Ring Network Topology 4.5 Heterogeneous Time Delays between Coupled PLLs 4.6 Phase Noise Analysis of Time Delay Coupled PLLs 4.6.1 Phase Noise for Two Mutually Coupled Nodes 4.6.2 The Impact of Coupling Directionality 4.6.3 Long Term Frequency Stability 4.6.4 Effect of Time Delay on Phase Noise 4.6.5 Network Topology Dependency on Phase Noise 5 Conclusion and Future Prospects Bibliography Own Publications – Periodicals Own Publications – Conference Proceedings Co-Authored Publications Other References List of Figures List of Tables Acknowledgement Curriculum Vitae

Frequency reference oscillator is a critical component of modern radio transceivers. Currently, most reference oscillators are based on low-frequency quartz crystals that are inherently bulky and incompatible with standard micro-fabrication processes. Moreover, their frequency limitation (<200MHz) requires large up-conversion ratio in multigigahertz frequency synthesizers, which in turn, degrades the phase-noise. Recent advances in MEMS technology have made realization of high-frequency on-chip low phase-noise MEMS oscillators possible. Although significant research has been directed toward replacing quartz crystal oscillators with integrated micromechanical oscillators, their phase-noise performance is not well modeled. In addition, little attention has been paid to developing electronic frequency tuning techniques to compensate for temperature/process variation and improve the absolute frequency accuracy. The objective of this dissertation was to realize high-frequency temperature-compensated high-frequency (>100MHz) micromechanical oscillators and study their phase-noise performance. To this end, low-power low-noise CMOS transimpedance amplifiers (TIA) that employ novel gain and bandwidth enhancement techniques are interfaced with high frequency (>100MHz) micromechanical resonators. The oscillation frequency is varied by a tuning network that uses frequency tuning enhancement techniques to increase the tuning range with minimal effect on the phase-noise performance. Taking advantage of extended frequency tuning range, and on-chip temperature-compensation circuitry is embedded with the sustaining circuitry to electronically temperature-compensate the oscillator. Finally, detailed study of the phase-noise in micromechanical oscillators is performed and analytical phase-noise models are derived.

Low noise low division 2 GHz RF synthesizer integrated circuits (ICs) are conventionally implemented in some form of HBT process such as SiGe or GaAs. The research in this dissertation differs from convention, with the aim of implementing a synthesizer IC in a more convenient, low-cost Si-based CMOS process. A collection of techniques to push towards the noise and frequency limits of CMOS processes, and possibly other IC processes, is then one of the research outcomes. In a synthesizer low N-divider ratios are important, as high division ratios would amplify in-band phase noise. The design methods deployed as part of this research achieve low division ratios (4 ≤ N ≤ 33) and a high phase comparison frequency (>100 MHz). The synthesizer IC employs a first-order fractional-N topology to achieve increased frequency tuning resolution. The primary N-divider was implemented utilising current mode logic (CML) and the fractional accumulator utilising conventional CMOS. Both a conventional CMOS phase frequency detector (PFD) and a CML PFD were implemented for benchmarking purposes. A custom-built 4.4 GHz synthesizer circuit employing the IC was used to validate the research. In the 4.4 GHz synthesizer circuit, the prototype IC achieved a measured in-band phase noise plateau of L( f ) = -113 dBc/Hz at a 100 kHz frequency offset, which equates to a figure of merit (FOM) of -225 dBc/Hz. The FOM compares well with existing, but expensive, SiGe and GaAs HBT processes. Total IC power dissipation was 710 mW, which is considerably less than commercially available GaAs designs. The complete synthesizer IC was implemented in Austriamicrosystems‟ (AMS) 0.35 μm CMOS process and occupies an area of 3.15 x 2.18 mm2. / Dissertation (MEng)--University of Pretoria, 2010. / Electrical, Electronic and Computer Engineering / unrestricted

<p>Дисертација истражује најприхватљивије методе мерења стабилности фреквенције у<br />фреквенцијском домену, односно мерење вредности величине &bdquo;фазни шум&ldquo;, приликом<br />процеса еталонирања мерне опреме. Када се говори о мерној опреми која је предмет<br />еталонирања, дисертација је, пре свега, окренута ка еталонирању врхунских<br />комерцијалних стандарда (еталона) фреквенције. Приказана истраживања су била основ<br />за покретање и реализацију истраживачко-развојног пројекта у оквиру Министарства<br />одбране, који је имао за циљ оспособљавање метролошке лабораторије Техничког<br />опитног центра Војске Србије за потпуно еталонирање мерне опреме из области<br />времена и фреквенције. Различите методе мерења подразумевају и различите мерне<br />могућности, као и врло широк спектар еталонске и мерне опреме која се користи при<br />њиховој реализацији. У дисертацији се приказују различити начини мерења фазног шума<br />и описују методе реализоване на основу доступне мерне опреме. Како се ради о<br />методама упоредне анализе референтног и мереног сигнала, посебно критична позиција<br />је одабир референце, односно референтног еталона. Истраживање је довело до<br />закључака којима је предложен метод мерења потребне и довољне мерне несигурности<br />као и начин реализације изабране методе, односно одабир еталонске мерне опреме. У<br />циљу увођења мерне методе у употребу, извршена су и приказана мерења на<br />различитим типовима и врстама мерне опреме. Валидација методе је остварена<br />билатералним поређењем са Дирекцијом за мере и драгоцене метале, Група за време,<br />фреквенцију и дистрибуцију времена. Да је могуће реализовати методу мерења фазног<br />шума приликом еталонирања најквалитетнијих осцилатора је постављена хипотеза<br />дисертације, која је истраживањем доказана и практично спроведена. Крајњи резултат<br />истраживања је довео до увођења признате методе еталонирања фазног шума, први пут</p> / <p>Disertacija istražuje najprihvatljivije metode merenja stabilnosti frekvencije u<br />frekvencijskom domenu, odnosno merenje vrednosti veličine &bdquo;fazni šum&ldquo;, prilikom<br />procesa etaloniranja merne opreme. Kada se govori o mernoj opremi koja je predmet<br />etaloniranja, disertacija je, pre svega, okrenuta ka etaloniranju vrhunskih<br />komercijalnih standarda (etalona) frekvencije. Prikazana istraživanja su bila osnov<br />za pokretanje i realizaciju istraživačko-razvojnog projekta u okviru Ministarstva<br />odbrane, koji je imao za cilj osposobljavanje metrološke laboratorije Tehničkog<br />opitnog centra Vojske Srbije za potpuno etaloniranje merne opreme iz oblasti<br />vremena i frekvencije. Različite metode merenja podrazumevaju i različite merne<br />mogućnosti, kao i vrlo širok spektar etalonske i merne opreme koja se koristi pri<br />njihovoj realizaciji. U disertaciji se prikazuju različiti načini merenja faznog šuma<br />i opisuju metode realizovane na osnovu dostupne merne opreme. Kako se radi o<br />metodama uporedne analize referentnog i merenog signala, posebno kritična pozicija<br />je odabir reference, odnosno referentnog etalona. Istraživanje je dovelo do<br />zaključaka kojima je predložen metod merenja potrebne i dovoljne merne nesigurnosti<br />kao i način realizacije izabrane metode, odnosno odabir etalonske merne opreme. U<br />cilju uvođenja merne metode u upotrebu, izvršena su i prikazana merenja na<br />različitim tipovima i vrstama merne opreme. Validacija metode je ostvarena<br />bilateralnim poređenjem sa Direkcijom za mere i dragocene metale, Grupa za vreme,<br />frekvenciju i distribuciju vremena. Da je moguće realizovati metodu merenja faznog<br />šuma prilikom etaloniranja najkvalitetnijih oscilatora je postavljena hipoteza<br />disertacije, koja je istraživanjem dokazana i praktično sprovedena. Krajnji rezultat<br />istraživanja je doveo do uvođenja priznate metode etaloniranja faznog šuma, prvi put</p> / <p>The dissertation examines the most acceptable methods for measuring the frequency stability<br />in the frequency domain, that is, measuring the value of the &quot;phase noise&quot;, during the process<br />of measuring equipment calibration. When it comes to measuring equipment as a subject of<br />calibration, the dissertation is, first of all, oriented towards the calibration of the highest<br />commercial frequency standards. The presented researches were the basis for initiation and<br />realization of the research and development project within the Ministry of Defense, which was<br />aimed at training the metrology laboratory of the Technical Test Center of the Serbian Army<br />for complete calibration of measuring equipment in the area of time and frequency. Different<br />measurement methods also involve different measurement possibilities, as well as a very wide<br />range of calibration and measuring equipment used in their realization. Different methods of<br />measuring phase noise are described in the dissertation and they describe realized methods<br />based on available measuring equipment. As for methods of comparative analysis of the<br />reference and measured signal, a particularly critical position is the selection of the reference,<br />that is, the reference oscillator. The research led to conclusions suggesting the method of<br />measuring the necessary and sufficient measurement uncertainty, as well as the method of<br />realization of the chosen method, i.e. selection of the standard measuring equipment. In order<br />to put the measurement method into practice, measurements were performed on different<br />types of measuring equipment. Validation of the method was achieved by bilateral<br />comparison with the Directorate of Measures and Precious Metals, Group for time, frequency<br />and time dissemination. The possibility to realize the method of phase noise measurement<br />during the calibration of the highest quality oscillators is a hypothesis of the dissertation that<br />has been set up, and has been proven and practically carried out by the research. The final<br />result of the research led to the introduction of a recognized calibration method of the phase<br />noise, for the first time in the Republic of Serbia.</p>

Coherent detection together with multilevel modulation formats has the potential to significantly increase the capacity of existing optical communication systems at no extra cost in signal bandwidth. However, these modulation formats are more susceptible to the impact of different noise sources and distortions as the distance between its constellation points in the complex plane reduces with the modulation index. In this context, digital signal processing (DSP) plays a key role as it allows compensating for the impairments occurring during signal generation, transmission and/or detection relaxing the complexity of the overall system. The transition towards pluggable optical transceivers, offers flexibility for network design/upgrade but sets strict requirements on the power consumption of the DSP thus limiting its complexity. The DSP module complexity however, scales with the modulation order and, in this scenario, low complex yet high performance DSP algorithms are highly desired. In this thesis, we mainly focus on the impact of laser phase noise arising from the transmitter and local oscillator (LO) lasers in coherent optical communication systems employing high order modulation formats. In these systems, the phase noise of the transmitting and LO lasers translate into phase noise in the received constellation impeding the proper recovery of the transmitted data. In order to increase the system phase noise tolerance, we firstly explore the possibility of re-arranging the constellation points in a circularly shaped mQAM (C-mQAM) constellation shape to exploit its inherent phase noise tolerance. Different low-complex carrier phase recovery (CPR) schemes applicable to these constellations are proposed along with a discussion on its performance and implementation complexity. Secondly, the design guidelines of high performance and low complex CPR schemes for conventional square mQAM constellations are presented. We identify the inherent limitation of the state-of-the-art blind phase search (BPS) carrier phase recovery algorithm which hinders its achievable performance and implementation complexity and present a low complex solution to overcome it. The design guidelines of multi-stage CPR schemes for high order modulation formats, where the BPS algorithm is employed at any of the stages, are also provided and discussed. Finally, the interplay between the received dispersed signal and the LO phase noise is analytically investigated to characterize the origin of the equalization enhanced phase noise phenomena. / <p>QC 20170516</p> / EU project ICONE, gr. #608099

Depuis quelques décennies, la technologie de contrôle de la fréquence a été au coeur de l'électronique des tempsmodernes grâce à son vaste domaine d'applications dans les systèmes de communication, les ordinateurs, les systèmesde navigation ou de défense militaire. Les dispositifs temps-fréquence fournissent des stabilités de fréquence et despuretés spectrales élevées dans le domaine de la stabilité court-terme. L'amélioration de la performance de cesdispositifs reste un grand défi pour les chercheurs. La réduction du bruit afin d'augmenter cette stabilité court-terme etd'éviter les commutations non souhaitées entre les canaux est donc très souhaitable. Il est communément admis que lalimitation fondamentale à cette stabilité court-terme est due au bruit flicker de fréquence des résonateurs. Dans cemanuscrit, un premier chapitre rappelle quelques faits de base sur l’acoustique, la cristallographie et les définitions dudomaine temps-fréquence nécessaires à l’étude des résonateurs et oscillateurs ultra-stables. Le deuxième chapitre estconsacré à un résumé de la littérature sur le bruit de fréquence en 1/f. Ensuite, le troisième chapitre concerne nos étudessur le modèle quantique de bruit en 1/f du Pr. Handel, qui, bien que critiqué par beaucoup, est encore le seul qui fournitune estimation de l'amplitude de plancher de bruit en 1/f et qui n'est pas infirmé par les données expérimentales. Dans lequatrième chapitre, une autre approche, basée sur le théorème de fluctuation-dissipation, est utilisée afin de mettre descontraintes numériques sur un modèle de bruit en 1/f causé par une dissipation interne (ou de structure) proportionnelleà l'amplitude, et non à la vitesse. Le dernier chapitre est consacré aux résultats expérimentaux. Le design et lesparamètres du résonateur ultra-stable utilisé lors de cette étude sont décrits. Les mesures de bruit de phase sur plusieurslots de résonateurs sont données. Les mesures des paramètres de résonateur ont été effectuées à basse température afinde les corréler avec les résultats de bruit. Afin d'évaluer rapidement la qualité des différents résonateurs, une autreapproche dans le domaine temporel a été testée. Elle utilise des oscillations pseudo-périodiques transitoires mettant lesoscilloscopes numériques actuellement disponibles à leurs limites de capacité. Enfin, les conclusions et perspectivessont présentées. / Since a few decades, frequency control technology has been at the heart of modern day electronics due to its huge areaof applications in communication systems, computers, navigation systems or military defense. Frequency controldevices provide high frequency stabilities and spectral purities in the short term domain. However, improvement of theperformance of these devices, in terms of frequency stability, remains a big challenge for researchers. Reducing noise inorder to increase the short term stability and avoid unwanted switching between channels is thus very desirable. It iscommonly admitted that the fundamental limitation to this short-term stability is due to flicker frequency noise in theresonators. In this manuscript, a first chapter recalls some basic facts about acoustic, crystallography and definitions oftime and frequency domain needed to explore ultra-stable resonators and oscillators. The second chapter is devoted to asummary of the literature on flicker frequency noise. Then, the third chapter concerns our studies on Handel’s quantum1/f noise model, which although criticized by many, is still the only one that provides an estimation of the flooramplitude of 1/f noise that is not invalidated by experimental data. In the fourth chapter, another approach, based on thefluctuation-dissipation theorem, is used in order to put numerical constraints on a model of 1/f noise caused by aninternal (or structural) dissipation proportional to the amplitude and not to the speed. The last chapter is devoted toexperimental results. An ultra-stable resonator used during this study is described. Phase noise measurements on severalbatches of resonators are given. Measurements of resonator parameters have been done at low temperature in order tocorrelate them with noise results. Another approach with a procedure that use transient pseudo periodic oscillations andput to their limits the capacities of presently available digital oscilloscopes, is presented, in order to assess rapidly thequality of various resonators. Finally, conclusions and perspectives are given.

L'optomécanique est la science des interactions entre la lumière et les mouvements mécaniques. Ce rapport de thèse décrit des expériences réalisées avec des microdisques fabriqué dans différents résonateurs semi-conducteurs III-V: l'Arséniure de Gallium (GaAs), l'Arséniure d'Aluminium Gallium (AlGaAs) et l'Arséniure d'Indium Phosphide (InGaP). Ces matériaux sont compatibles avec les fonctionnalités de l’optoélectronique et procurent un couplage optomécanique géant. Pour améliorer les performances des résonateurs en GaAs, nous avons développé des méthodes de traitement de surface permettant de réduire la dissipation optique par un facteur dix et ainsi d'atteindre un facteur de qualité de six millions. En plus de ces études sur le GaAs, nous avons réalisés une étude comparative des interactions optomecaniques dans des microdisques d'InGaP et d'AlGaAs, et nous avons mis en évidences leurs résonances optomécaniques. Finalement, nous avons réalisé des mesures de force avec des résonateurs en GaAs, démontrant un nouveau principe de détection basé sur notre étude de leur la trajectoire dans l'espace de phase et leur bruit de phase / Optomechanics studies the interaction between light and mechanical motion. This PhD thesis reports on optomechanical experiments carried with miniature disk resonators fabricated out of distinct III-V semiconductors: Gallium Arsenide (GaAs), Aluminium Gallium Arsenide (AlGaAs) and Indium Gallium Phosphide (InGaP). These materials are compliant with optoelectronics functionalities and provide giant optomechanical coupling. In order to boost performances of GaAs resonators, we implemented surface control techniques and obtained a ten-fold reduction of optical dissipation, attaining a Q of six million. On top of GaAs, we performed a comparative investigation of optomechanical interactions in InGaP and AlGaAs disk resonators, and demonstrated their operation as optomechanical oscillators. Finally, we carried out optomechanical force sensing experiments with GaAs resonators, analyzing a new sensing principle in light of the phase space trajectory and phase noise of the corresponding oscillators

The L5 signal of the Global Positioning System (GPS) is becoming available on an increasing number of Block IIF satellites. As the third civilian signal, L5 is superior in signal design to the L1 C/A and L2C civilian signals. This new signal has been marked healthy for use on selected satellites since 2010, yet the hardware capable of tracking the L5 signal is still in the early stages of development. This work investigates the characteristics of the new signal and the quality of data produced by L5-tracking receivers. Commonly used receiver models chosen for this study are the Leica GRX1200+GNSS, the Trimble NetR8, and the Javad Delta TRE-G3TH. The metrics used in this analysis to assess the quality of data produced by these receivers are signal strength, receiver phase noise, receiver code noise, and multipath. The data used in these analyses were obtained from the International GNSS Service for the days of the year 275 to 281 in 2011. Metrics averaged over the GPS week 1656 provide a good indication of the overall performance of the receivers. / text