The nano-contact spin torque oscillator (NC-STO) is an emerging device for highly tunable microwave frequency generation in the range from 0.1 GHz to above 65 GHz with an on-chip footprint on the scale of a few μm. The frequency is inherent to the magnetic material of the NC-STO and is excited by an electrical DC current by means of the spin torque transfer effect. Although the general operation is well understood, more detailed aspects such as a generally nonlinear frequency versus current relationship, mode-jumping and high device-to-device variability represent open questions. Further application-oriented questions are related to increasing the electrical output power through synchronization of multiple NC-STOs and integration with CMOS integrated circuits. This thesis consists of an experimental part and a simulation part. Experimentally, for the frequency stability it is found that the slow but strong 1/f-type frequency fluctuations are related to the degree of nonlinearity and the presence of perturbing, unexcited modes. It is also found that the NC-STO can exhibit up to three propagating spin wave oscillation modes with different frequencies and can randomly jump between them. These findings were made possible through the development of a specialized microwave time-domain measurement circuit. Another instrumental achievement was made with synchrotron X-rays, where we image dynamically the magnetic internals of an operating NC-STO device and reveal a spin wave mode structure with a complexity significantly higher than the one predicted by the present theory. In the simulations, we are able to reproduce the nonlinear current dependence by including spin wave-reflecting barriers in the nm-thick metallic, magnetic free layer. A physical model for the barriers is introduced in the form of metal grain boundaries with reduced magnetic exchange coupling. Using the experimentally measured average grain size of 30 nm, the spin wave mode structure resulting from the grain model is able to reproduce the experimentally found device nonlinearity and high device-to-device variability. In conclusion, the results point out microscopic material grains in the metallic free layer as the reason behind the nonlinear frequency versus current behavior and multiple propagating spin wave modes and thereby as a source of device-to-device variability and frequency instability. / Dagens snabba utveckling inom informationsteknik drivs på av ständigt växande informationsmängder och deras samhällsanvändning inom allt från resursoptimering till underhållning. Utvecklingen möjliggörs till stor del hårdvarumässigt av miniatyrisering och integrering av elektroniska komponenter samt trådlös kommunikation med allt större bandbredd och högre överföringshastighet. Det senare uppnås främst genom utnyttjande av högre radiofrekvenser i teknologiskt tidigare oåtkomliga delar av spektrumet. Frekvensutnyttjandet har det senaste årtiondet ökat markant i mikrovågsområdet med typiska frekvenser runt 2.4 GHz och 5.2-5.8 GHz. I den spinntroniska oscillatorn (STO:n) möjliggörs frekvensgenerering i det breda området från 0.1 GHz upp till över 65 GHz av en komponent med mikrometerstorlek som kan integreras direkt i CMOS-mikrochip. Till skillnad från i konventionella radiokretsar med oscillatorer konstruerade av integrerade transistorer och spolar, genereras mikrovågsfrekvensen direkt i STO:ns magnetiska material och omvandlas därefter till en elektrisk signal genom komponentens magnetoresistans. Dessa materialegenskaper möjliggör ett tillgängligt frekvensband med extrem bredd i en och samma STO, som därtill kan frekvensmoduleras direkt genom sin styrström och på så sätt förenklar konstruktionen av sändarsystem. STO:ns icke-linjära egenskaper kan potentiellt också användas för att i en och samma komponent blanda ned mottagna mikrovågssignaler och på så sätt förenkla konstruktionen även av mikrovågsmottagare. STO:ns signalegenskaper bestäms av det magnetiska materialets fysik i form av magnetiseringsdynamik driven av elektriskt genererade spinnströmmar. I denna avhandling studeras denna dynamik experimentellt med särskilt fokus på frekvensstabiliteten i den hittills mest stabila STO-typen; nanokontakts-STO:n. Genom mätningar i tidsdomän av STO:ns elektriska signaler runt 25 GHz har frekvensstabiliteten funnits hänga samman med den typ av icke-linjärt beteende som också funnits vara utmärkande för tillverkningsvariationen i komponenterna. Mikroskopiska undersökningar av materialet visar att en trolig källa till denna variation är den magnetiska metallens uppbyggnad i form av korn i storleksordningen 30 nm, och datorsimuleringar av en sådan materialstruktur har visats kunna reproducera de experimentella resultaten. Därtill har en metod utvecklats för att med röntgenstrålning direkt mäta de små, magnetiska mikrovågsrörelserna i materialet. Denna röntgenteknik möjliggör detaljerade experimentella studier av magnetiseringsdynamiken och kan användas för att verifiera och vidareutveckla den existerande teorin för mikrovågsspinntronik. Sammantaget förs STO-teknologin genom denna studie ett steg närmare sina tänkbara samhällsbreda tillämpningar inom snabb, trådlös kommunikation för massproducerade produkter med integrerad sensor- och datorfunktionalitet. / <p>QC 20160620</p>

Thesis (MScEng (Electrical and Electronic Engineering))--Stellenbosch University, 2008. / The topic for this project entailed the development of a ‘Low Phase Noise – Microwave – Voltage Controlled Oscillator’ for use in radar applications. First of all, a low phase noise oscillator was designed. In order to minimise the phase noise of the oscillator, a high-Q, transmission line – cavity resonator was developed. By derivation it was confirmed that an optimal point for minimum phase noise does exist. The latter was done by evaluating the equation for the output power spectral density of the oscillator phase noise (as defined by Leeson’s Phase Noise Model) at its minimum point. Subsequently, the amount of power that needed to be dissipated inside the resonator could be compared to that dissipated in the source and the load. This identified the amount of coupling to the resonator allowed, assuring minimum phase noise. Since a specific amount of coupling to the resonator was sought after, it had to be practically feasible. Therefore several coupling techniques were investigated to ensure the most user-friendly way of tuning the amount of coupling to the resonator, and hence easily reaching the optimum point of minimum phase noise. After successful completion of the low phase noise oscillator design, it was modified for voltage controlled oscillator (VCO) use by means of variable tuning diodes. These varactor diodes were situated inside the cavity of the resonator. Again the most suitable position to place the diodes had to be determined. The latter was done through considerably detailed transmission line theory; where the loaded Q, the tuning bandwidth (amount of change in frequency reached) and the amount of power dissipated inside the resonator were measured against each other. By means of the necessary phase noise measurements, it was confirmed that in order to keep the phase noise to a minimum, the tuning bandwidth had to be kept small and the amount of power dissipated inside the resonator maximised; so as to keep the overall loaded Q-value of the circuit as high as possible.

Le travail en bande de base permet de s’affranchir du bruit de multiplication de fréquenced’un signal. Cependant, la conception d’un oscillateur fonctionnant à haute fréquence nécessited’avoir un composant sélectif en fréquence, fonctionnant à haute fréquence et avec un facteurde qualité élevée. L’approche proposée dans cette thèse consiste à évaluer un composant à ondeélastique de volume à harmoniques élevées, le HBAR, pour la réalisation d’un oscillateur compactet stable, travaillant en bande de base à 2,45 GHz, à des fins d’utilisation de source defréquence pour un système RADAR. Les oscillateurs réalisés présentent un bruit de phase de-100 dBc/Hz pour un écart à la porteuse de 1 kHz, avec une perspective d’amélioration d’une dizainede dBc/Hz de cette valeur d’après la simulation. L’étude porte également sur l’analyse del’influence du bruit de phase de l’oscillateur local sur la résolution d’une mesure RADAR dontl’effet est démontré expérimentalement en utilisant une ligne à retard à onde élastique de surface(SAW) comme cible RADAR coopérative. Le travail effectué sur cette cible coopérative apermis d’aboutir à un prototype d’électronique embarqué pour l’interrogation de lignes à retardà ondes élastiques utilisées en tant que capteurs passifs interrogeables à distance. L’architecturede l’interrogateur combine une méthode RADAR impulsionnelle à un système d’échantillonnageen temps équivalent permettant de réduire l’importance de la puissance de calcul dansle traitement de la réponse. Les inconvénients de l’échantillonnage en temps équivalent sontminimisés par une interrogation judicieuse pour acquérir seulement les points nécessaires à lamesure. Les mesures effectuées sur un capteur de température commercial présentent une résolutionde 0,2°C avec une bande passante de 35 kHz. Pour les applications nécessitant une bandepassante plus élevée (allant jusqu’à 200 kHz), un second prototype n’ayant pas de restrictionsur les ressources de calcul mises en oeuvre est également présenté dans cette thèse, combinantla même méthode impulsionnelle avec un échantillonnage en temps réel. / Eliminating the step of frequency multiplication, by working in baseband, reduces the phasenoise of an oscillator. However, the design of a high frequency oscillator requires a frequencyselective component, which operates at high frequency and with a high quality factor. The approachproposed in this thesis is to evaluate a High-overtone Bulk Acoustic-wave Resonator,the HBAR, for the realization of a compact and stable oscillator at 2.45 GHz for a RADAR system.The designed oscillator exhibits a phase noise of −100 dBc/Hz at 1 kHz from the carrier,with an expected improvement of a dozen dBc/Hz according to the simulation. The study alsofocuses on the analysis of the local oscillator phase noise impact on the resolution of a RADARmeasurement and an experimental demonstration is done using a delay line surface acousticwave (SAW) as cooperative RADAR target. The work on this cooperative target has lead to aprototype of an embedded electronics for interrogating surface acoustic wave delay lines usedas passive sensors remotely interrogated through a wireless link. The architecture combines thepulsed RADAR signal generation method with an equivalent time sampling system in orderto reduce the computing power needed to process the response. The disadvantages of equivalenttime sampling are minimized by a smart interrogation strategy to acquire only mandatorysamples. Measurements on a commercial temperature sensor have a resolution of 0.2°C witha 35 kHz bandwidth. For applications in need of higher bandwidth (up to 200 kHz), a secondprototype with no restriction on computing resources is also presented in this thesis, combiningthe same impulse RADAR method with real-time sampling.

Les oscillateurs sont présents dans tous les systèmes de communications que nous utilisons. Ils nous permettent de faire la synchronisation entre l’émetteur et le récepteur d’un message. La qualité de cette synchronisation dépend de la stabilité de l’oscillateur. Afin de caractériser cette stabilité dans le domaine fréquentiel, le bruit de phase est utilisé comme paramètre de référence. Un oscillateur qui délivre un signal avec une faible valeur de bruit de phase est un oscillateur de grande pureté spectrale. Les oscillateurs électroniques ont une bonne performance à basse fréquence. En mesure de la demande des systèmes de très haut débit, les oscillateurs électroniques ne sont pas capables de produire signaux qu’avec l’utilisation de multiplicateurs de fréquence qui ajoutent plusieurs éléments à la chaine de communication. Les systèmes hybrides permettent de prendre d’avantage la bonne performance de composants optiques en haute fréquence afin de les intégrer dans les systèmes électroniques et surmonter de cette façon-là les limitations fréquentielles des systèmes électroniques. Ce travail vise l’utilisation de la technique de verrouillage optique par injection du faisceau d’un laser maître vers la cavité d’un VCSEL sous modulation directe dans la boucle d’oscillation. La technique du verrouillage optique du VCSEL permets d’élargir la bande passante de modulation directe du VCSEL et réduire son bruit d’intensité (Relative Intensity Noise - RIN). La réduction du RIN a comme effet secondaire la réduction de la contribution du bruit additif dans l’oscillateur et, en conséquence, la réduction du bruit de phase de l’oscillateur. / Oscillators are present in all telecommunication systems. They synchronize the emitter and receiver of a message. The quality of the synchronization depends on the oscillator stability. To characterize the frequency domain oscillator stability, the phase noise of the carrier is used as figure of merit. An oscillator delivering a low phase noise carrier is a high spectral purity oscillator. Electronic oscillators are high performing at low frequencies. As communications systems require high data rate transmission, the electronic oscillators uses frequency multipliers that degrades the spectral purity of the carrier. The hybrid systems take advantage of the good performance of optical components at high frequency with the goal to be integrated in the electronic systems to overcome frequency limitation issues. This work use the optical injection locking technique by injecting the laser beam of a master laser inside the cavity of a VCSEL under direct modulation. The optical injection locking technique enlarges the direct modulation bandwidth of the VCSEL and reduces the Relative Intensity noise of the laser (RIN). The RIN reduction has as side effect the reduction of the additive noise inside the oscillator and, in consequence, reducing the oscillator phase noise.

Nesta dissertação os conceitos e técnicas relacionadas com a automação e otimização do projeto de um oscilador controlável por tensão para aplicações de rádio frequência são apresentados. O problema de projeto do oscilador foi formulado como um problema de otimização matemática conhecido como programação geométrica. Uma abordagem à aplicação da programação geométrica no projeto de um circuito simples foi feita primeiro. Dessa forma, as vantagens e limitações da metodologia são identificadas e propostas para lidar com esses problemas são revisados. Com uma idéia clara da metodologia, o problema de projeto do oscilador como um programa geométrico é apresentado. Um requerimento importante da aplicação de programação geométrica no projeto de circuitos é a necessidade de contar com modelos dos dispositivos que sejam compatíveis com a forma matemática do problema de otimização. Nesse sentido, neste trabalho se mostra como foram obtidos esses modelos para parâmetros do transistor e de um indutor quadrado simétrico onchip. Finalmente, aplicou-se a metodologia no projeto de um VCO na banda ISM 2.4GHz numa tecnologia CMOS 0.35um padrão de 4 metais, simulações do circuito mostraram uma figura de mérito de 180dBc/Hz com o ruído de fase de -130dBc/Hz a 3MHz de offset da portadora. Finalmente, o layout do protótipo de um VCO foi feito e fabricado. Testes experimentais foram desenvolvidos. Os resultados obtidos mostraram boa correlação com as simulações póslayout do circuito. / In this work the concepts and techniques related to the optimization and automation of the design of a controlled voltage oscillator intended for radio frequency applications are presented. The design problem of the oscillator was cast as a mathematical optimization problem known as geometric programming. As a first approach, the application of geometric programming in the design of a simple circuits was done. Thus, the advantages and limitations of the methodology were first reviewed and strategies to overcome theses problems were also presented. With a better understanding of the methodology, the formulation of the oscillator as a geometric program was presented. One of the most important requirements in the application of geometric programming in circuit design is the needed of device models suitable with the mathematical form of a geometric program. Thus, in this work the techniques used to obtain theses models for transistor and inductor parameters were presented. Using the proposed methodology, a VCO for the 2.4GHz ISM frequency band was designed in a standard 4 metals 0.35um CMOS technology. From simulations results, the VCO achieved a figure of merit of 180 dBc/Hz with a phase noise of -130dBc/Hz at 3MHz of offset frequency. A prototype of a VCO was fabricated and experimental tests were developed. From the obtained results good agreement with post layout simulations were observed.

Nesta dissertação os conceitos e técnicas relacionadas com a automação e otimização do projeto de um oscilador controlável por tensão para aplicações de rádio frequência são apresentados. O problema de projeto do oscilador foi formulado como um problema de otimização matemática conhecido como programação geométrica. Uma abordagem à aplicação da programação geométrica no projeto de um circuito simples foi feita primeiro. Dessa forma, as vantagens e limitações da metodologia são identificadas e propostas para lidar com esses problemas são revisados. Com uma idéia clara da metodologia, o problema de projeto do oscilador como um programa geométrico é apresentado. Um requerimento importante da aplicação de programação geométrica no projeto de circuitos é a necessidade de contar com modelos dos dispositivos que sejam compatíveis com a forma matemática do problema de otimização. Nesse sentido, neste trabalho se mostra como foram obtidos esses modelos para parâmetros do transistor e de um indutor quadrado simétrico onchip. Finalmente, aplicou-se a metodologia no projeto de um VCO na banda ISM 2.4GHz numa tecnologia CMOS 0.35um padrão de 4 metais, simulações do circuito mostraram uma figura de mérito de 180dBc/Hz com o ruído de fase de -130dBc/Hz a 3MHz de offset da portadora. Finalmente, o layout do protótipo de um VCO foi feito e fabricado. Testes experimentais foram desenvolvidos. Os resultados obtidos mostraram boa correlação com as simulações póslayout do circuito. / In this work the concepts and techniques related to the optimization and automation of the design of a controlled voltage oscillator intended for radio frequency applications are presented. The design problem of the oscillator was cast as a mathematical optimization problem known as geometric programming. As a first approach, the application of geometric programming in the design of a simple circuits was done. Thus, the advantages and limitations of the methodology were first reviewed and strategies to overcome theses problems were also presented. With a better understanding of the methodology, the formulation of the oscillator as a geometric program was presented. One of the most important requirements in the application of geometric programming in circuit design is the needed of device models suitable with the mathematical form of a geometric program. Thus, in this work the techniques used to obtain theses models for transistor and inductor parameters were presented. Using the proposed methodology, a VCO for the 2.4GHz ISM frequency band was designed in a standard 4 metals 0.35um CMOS technology. From simulations results, the VCO achieved a figure of merit of 180 dBc/Hz with a phase noise of -130dBc/Hz at 3MHz of offset frequency. A prototype of a VCO was fabricated and experimental tests were developed. From the obtained results good agreement with post layout simulations were observed.

Os diodos laser são amplamente usados em física atômica em configurações de cavidade externa com uma rede de difração (Configuração Littrow ou Littrow-Metcalf), que permite sintonizar o seu comprimento de onda e filtrar do seu espectro. Mesmo com este controle, eles apresentam um excesso de ruído por volta de 40 dB acima do ruído quântico padrão, dificultando seu uso em ótica quântica. Nosso propósito neste projeto é diminuir os valores típicos de ruído do diodo laser até níveis aceitáveis que permitam trabalhar em ótica quântica. Para conseguir isto, construímos um laser em estrutura em anel com o diodo semicondutor como o meio de ganho. Caracterizamos a potência de saída do laser em função da corrente de injeção no chip. Também introduzimos um mecanismo de controle das perdas da cavidade para caracterizar a potência de saída em função das perdas. Alcançamos uma potência máxima de 25 mW para 0, 8 A, com um limiar de oscilação de 0, 45 A, e uma potência máxima de 10 mW (a 0, 8 A) com um limiar de 0, 41 A. Para caracterizar as suas propriedades de ruído, usamos a técnica da rotação de elipse para diferentes valores da corrente de injeção e de perdas controladas. Finalmente, comparamos o ruído das quadraturas do nosso novo sistema com o ruído de um laser de diodo em configuração Littrow. Enquanto o laser Littrow apresenta excesso de 40 dB no ruído da fase, encontramos valores para o ruído de amplitude do nosso novo laser entre 10 e 15 dB e do ruído de fase entre 11 e 27 dB acima do nível do ruído quântico padrão. Assim, conseguimos diminuir o ruído da quadratura fase por volta de 20 dB, porém, também incrementamos o ruído de amplitude, fazendo com que o ruído das quadraturas esteja no nível de 11 dB acimo do nível do ruído quântico padrão. Este nível é compatível com laseres de estado sólido (Nd:YAG) e pode ser facilmente reduzido com ajuda de uma cavidade de filtro. / Laser diodes are widely used in atomic physics in configurations of external cavity with a diffraction grating (Littrow or Littrow-Metcalf configuration), that allows us to tune its wavelength and filter their spectrum. Even with this control they present an excess noise about 40 dB above the standard quantum level,limiting their uses for quantum optics. Our goal in this project is to decrease the typical noise level of the diode laser, to reasonable values for future work with quantum optics. In order to do that we built a ring laser using a semiconductor chip as the gain medium. We characterize the output power of the laser as a function of the injection current. We also introduce a mechanism for controlling the losses so that, we were able to characterize the output power by changing the controlled losses. We reach a maximum power of 25 mW at 0.8 A, with the threshold current value 0.45 A, and a maximum power of 10 mW (@ 0.8 A) for 0.41 A of threshold current. In order to characterize its noise properties, we performed the ellipse rotation technique for different values of the injection current and controlled looses. Finally, we compare the quadrature noise of our new system with the noise of a diode laser in Littrow configuration. While Littrow laser present excess of of 40 dB on the phase noise, we found noise levels for the amplitude noise of our new laser between 10 to 15 dB and its phase noise between 11 to 27 dB above the standard quantum level. So, we achieved a noise reduction of the phase quadrature in 20 dB, but, we also increase the amplitude noise, obtaining a quadrature noise around 11 dB above the standard quantum limit. This level is compatible with solid state lasers (Nd:YAG) and can be easily reduced with the help of a filter cavity.

La tesi estudia el problema de la síntesi de freqüències en les bandes de freqüències de microones i ones mil·limètriques, i la seva aplicació al disseny dels oscil·ladors locals d'un receptor coherent per a la recepció de les *radiobalises que a 12, 20 i 30 GHz emetia el satèl·lit Olympus de l'Agència Espacial Europea (ESA), amb la finalitat de caracteritzar el comportament radioelèctric de l'atmosfera a aquestes freqüències, a partir de mesures d'atenuació i transpolarització sobre aquests senyals de test, tot això dintre del marc d'un experiment de propagació (OPEX) propiciat per l'agència.La tesi s'ha centrat en l'estudi dels sistemes de síntesis de freqüències utilitzats habitualment, i especialment en els de síntesi indirecta de freqüència basats en sistemes Phase Locked Loop (PLL) a freqüències de microones ja que són la base sobre la qual s'han dissenyat i construït els prototips de multiplicadors de freqüència que s'han desenvolupat, capaços de sintetitzar senyals en bandes de mil·limètriques, que en el nostre cas s'han restringit al marge de 1 a 29 GHz.Alguns dels multiplicadors fan ús de la detecció de fase harmònica, sistema que permet realitzar multiplicacions de freqüència d'índex imparell, evitant la utilització de divisors de freqüència en el llaç de realimentació del PLL.La tesi s'estructura en quatre parts diferenciades. La primera, amb un caire eminentment teòric, s'ofereix a manera de revisió dels aspectes del soroll de fase i dels sistemes de síntesis de freqüències existents. La segona part aborda les qüestions derivades de la síntesi de freqüències en microones mitjançant PLL's, amb descripció dels components utilitzats, per a passar a tractar dels aspectes de disseny d'un receptor coherent, els seus requisits i aplicacions. En la tercera part es presenten els multiplicadors de freqüència realitzats, la seva descripció, esquema de blocs i resultats experimentals obtinguts. I finalment, en la quarta part s'inclouen una sèrie de realitzacions derivades de la utilització de sistemes PLL a freqüències de microones, amb sincronització per injecció del VCO al senyal de referència, en aplicacions de combinació de potència i de control electrònic de fase en sistemes phased-arrays amb elements actius. / La tesis estudia el problema de la síntesis de frecuencias en las bandas de frecuencias de microondas y ondas milimétricas, y su aplicación al diseño de los osciladores locales de un receptor coherente para la recepción de las radiobalizas que a 12, 20 y 30 GHz emitía el satélite Olympus de la Agencia Espacial Europea (ESA), con la finalidad de caracterizar el comportamiento radioeléctrico de la atmósfera a estas frecuencias, a partir de medidas de atenuación y transpolarización sobre esas señales de test, todo ello dentro del marco de un experimento de propagación (OPEX) propiciado por la agencia.La tesis se ha centrado en el estudio de los sistemas de síntesis de frecuencias utilizados habitualmente, y en especial en los de síntesis indirecta de frecuencia basados en sistemas Phase Locked Loop (PLL) a frecuencias de microondas puesto que son la base sobre la que se sustentan los prototipos de multiplicadores de frecuencia que se han desarrollado, capaces de sintetizar señales en bandas milimétricas, que en nuestro caso se han restringido al margen de 1 a 29 GHz.Algunos de los multiplicadores hacen uso de la detección de fase armónica, sistema que permite realizar multiplicaciones de frecuencia de índice impar, evitando el empleo de divisores de frecuencia en el lazo de realimentación del PLL.La tesis se estructura en cuatro partes diferenciadas. La primera, con un cariz eminentemente teórico, se ofrece a modo de revisión del tema del ruido de fase y de los sistemas de síntesis de frecuencias existentes. La segunda parte aborda las cuestiones derivadas de la síntesis de frecuencias en microondas mediante PLL's, con descripción de los componentes utilizados, para pasar a tratar de los aspectos de diseño de un receptor coherente, sus requisitos y aplicaciones. En la tercera parte se presentan los multiplicadores de frecuencia realizados, su descripción, esquema de bloques y resultados experimentales obtenidos. Y por último, en la cuarta parte se incluyen una serie de realizaciones derivadas de la utilización de sistemas PLL a frecuencias de microondas, con sincronización por inyección del VCO a la señal de referencia, en aplicaciones de combinación de potencia y de control electrónico de fase en sistemas phased-arrays con elementos activos. / The thesis studies the problem of the synthesis of frequencies in the microwave and millimeter waves frequency bands, and its application to the design of the local oscillators of a coherent receiver for the reception of the radio beacons that to 12, 20 and 30 GHz emitted the satellite Olympus from the European Space Agency (ESA), with the aim of characterizing the radio behavior of the atmosphere at these frequencies, from measurements of attenuation and transpolarisation on those signals of test, all that in the framework of a propagation experiment (OPEX) favored by the agency.The thesis has been focused on the study of the frequency synthesis systems, and especially on the indirect frequency synthesis systems based on Phase Locked Loops (PLL) at microwave frequencies, since they are the base on which the prototypes of frequency multipliers that they have been developed, capable of synthesizing signals in millimeter bands, are held that in our case they have restricted regardless of 1 to 29 GHz.Some of the multipliers make use of the harmonic phase detection system that allows carrying out frequency multiplications of odd index, preventing the use of frequency dividers in the feedback loop of the PLL.The thesis is structured in four differentiated parts. The first, with an eminently theoretical look, offers like revision of the subject of the phase noise and the methods of frequency synthesis. The second part tackles the questions derived from the synthesis of frequencies in microwaves through PLL's, with description of the used components, to pass to deal of the aspects of design of a coherent receiver, its requirements and applications. In the third part the frequency multipliers carried out, its description, schema of blocks and obtained experimental results are presented. And finally, in the fourth part a series of accomplishments are included phased-arrays derived of the use of systems PLL at frequencies of microwaves, with synchronization by injection of the VCO to the reference signal, in applications of power combination and of electronic phase control in systems with active elements.

In this thesis, a low phase noise local oscillator operating at 2210 MHz is designed and implemented to be used in X-Band transmitter of a LEO satellite. Designed local oscillator is a PLL (Phase Locked Loop) based frequency synthesizer which is implemented using discrete commercial components including ultra low noise voltage controlled oscillator and high resolution, low noise fractional-N synthesizer. Operational settings of the synthesizer are done using three wire serial interface of a microcontroller. Although there are some imperfections in the implementation, phase noise of the prototype system is pretty good which is measured as -123.2 dBc/Hz at 100 kHz offset and less than -141.3 dBc/Hz at 1 MHz offset. Made up of discrete components, the VCO used in the designed local oscillator is not integrable to frequency synthesizer which is implemented in CMOS technology. Considering technological progress, integrabilitiy of system components becomes important for designing single chip complete systems like transmitters, receivers or transceivers. Therefore considering a potential single chip transceiver production, also a CMOS voltage controlled oscillator is designed using standard TSMC 0.18um technology operating in between 2.05 GHz and 2.35 GHz . Since low phase noise is the main concern, phase noise models and phase noise reduction techniques that are derived from the models are studied. These techniques are applied to the VCO core to see the effects. Design is finalized by applying some of those techniques which are found to be noticeably effective to the core design. Finalized core operates from 2.15 GHz to 2.25 GHz and phase noise is simulated as -107.265 dBc/Hz at 100 kHz offset and -131.167 dBc/Hz at 1 MHz offset. Also oscillator has figure of merit of -185.4 at 100 kHz offset. These values show that designed core is considerably good when compared to similar designs.

Στα πλαίσια της παρούσας διπλωματικής εργασίας μελετήθηκαν οι βασικές αρχές λειτουργίας και θορύβου στα Phase Locked Loops. Στη συνέχεια σχεδιάστηκε το σχηματικό και το layout ενός PLL μικτού σήματος στο λογισμικό σχεδίασης ολοκληρωμένων κυκλωμάτων, Cadence IC5141. Το κύκλωμα αυτό λειτουργεί σαν συνθέτης συχνοτήτων στην περιοχή των 5GHz, από μία συχνότητα αναφοράς 50MHz, έχει θόρυβο φάσης περίπου 88dBc στο 1MHz από το φορέα και μέση κατανάλωση λιγότερο από 30mW. / Analysis of basic operation principles and noise performance of Phase Locked Loops. Design of a PLL (schematic and layout) in Cadence IC5141.