International Telemetering Conference Proceedings / October 17-20, 1988 / Riviera Hotel, Las Vegas, Nevada / This paper describes the design, test and the analysis of the test results of a new type S-band FM telemetry transmitter. Compared with the modulator adopting conventional fundamental crystal direct modulation, the transmitter which adopts UHF fundamental crystal direct modulation has a comparatively better modulation characteristics and a higher center frequency stability. The test results show that the deviation sensitivity of the transmitter is up to 400KHz/Vrms, frequency response is DC~200 KHz, total harmonic distortion is 3% and the center frequency stability is ten to the minus fifth power within the range of - 30~+70°c. Because of the high operating frequency of the modulator, the complicacy of the frequency multiplier has been requced, design of circuitry simplified and harmonic and spurious outputs has been improved to a great extent.

Direct RF modulation on semiconductor lasers of wavelength 1310 nm has been widely applied to amplitude modulation vestigial side-band(AM-VSB)lightwave cable television (CATV) systems. The channel capacity is limited mainly by the nonlinear distortion of laser diode, which induces system performance degradation of composite second order (CSO) and composite triple beats (CTB). Though the linearity of laser diode has been improved during the fabrication process, carrier to noise ratio (CNR), CSO, and CTB were still degraded by increasing either RF output power level or the channel loading. Thus, some linearization techniques were proposed to extend the channel capacity. The predistortion approach is the simplest and the lowest cost one among the techniques. This paper describes a distortion compensation method with an electrical ¡§branch¡¨ circuit configuration, which is designed to reduce the nonlinear distortion induced by the laser diode. In this architecture, we utilize the method of impedance non-matching and the reflection of signals. According to the experiment results, we have found that before predistortion compensation, CNR / CSO / CTB are 51.6 dB / 62 dBc / 70 dBc, respectively. After compensation, CNR / CSO / CTB are 51.5 dB / 70 dBc / 71 dBc, respectively. Comparing with and without the distortion compensation, we found that CSO has an improvement with 8 dB, which reveals that the predistorion circuit improves the linearity of laser obviously. This study may give a guideline of predistortion technique and help to design optical transmitter.

With the rapid development of fiber access networks, data centers, 5th generation cellular networks, and many more, there is an increasing demand for cost effective light sources possessing specification including high frequency modulation efficiency, low noise figure, and high data rate up to 40 Gb/s or even 100 Gb/s. Semiconductor lasers are considered the most attractive candidate in such applications for their low cost, high energy efficiency, and compact size. The focus of this thesis is the development of novel designs of semiconductor DFB lasers for device performance improvement with the help of numerical simulation tools. The governing equations used in the simulation of DFB lasers are briefly explained, which covers the calculation of optical field, carrier transport, material gain, and thermal diffusion. The TWM based on these governing equations are adopted for the numerical laser solver used in the following chapters for device performance simulation. Three novel DFB structures are then proposed in the thesis to achieve different specifications. The first proposed structure is a three-electrode DFB laser which can be directly frequency modulated. Numerical simulation shows that a high frequency modulation efficiency of 26GHz/mA from 0 to 100GHz and 17GHz/mA from 100GHZ to 200GHz can be achieved, respectively. Large-signal simulation of the waveform and eye-diagram of a frequency shift-keying (FSK) signal generated by the laser is also performed by converting it to an amplitude shift-keying (ASK) signal through an optical slope filter. The second proposed structure is a DFB laser with asymmetric λ/8 phase-shifted grating designed to flatten the relaxation oscillation peak through longitudinal spatial hole burning (LSHB) effect. Optimization of the phase-shift position to be 25% (in terms of the total length of the cavity) away from the high reflective (HR)-coated facet leads to reduced power leakage thus a higher quality factor of the cavity. The combined effect provides an improved RIN figure for the proposed DFB laser. The third proposed structure is a DFB laser with periodic current blocking grating. This novel grating is designed to improve the modulation bandwidth of DFB lasers by exploiting the enhancement of net differential gain. The effectiveness of the design is verified numerically, and excellent 3dB bandwidth enhancement are found for both uniform grating and λ/4 phase-shifted grating structures. / Thesis / Doctor of Philosophy (PhD) / Semiconductor lasers are by far the most ubiquitous of all lasers, with their applications ranging from communication to manufacturing and from cooling of atoms to sensing of minor movement. And as the fabrication technique of semiconductor laser mature, numerical simulation tools now play the critical role in laser development. This thesis focuses on the design and simulation of novel structures for distributed-feedback (DFB) lasers to improve the performance of such devices, including the frequency tuning efficiency, relative intensity noise (RIN), and modulation bandwidth. The proposed new structures and the underlying ideas led to them are thoroughly explained in the thesis. The device performances are also investigated numerically by applying traveling wave method (TWM). Simulation results are presented and discussed to provide design guidelines for the proposed structures.

Afin de répondre à la demande croissante de nouveaux services, les objets que nous utilisons au quotidien (les smartphones, les voitures, les avions, etc.) tendent à intégrer de plus en plus de systèmes radio tandis que l’espace disponible pour l’intégration de ces éléments est de plus en plus réduit. Ces systèmes radio nécessitent l’utilisation de plusieurs antennes devant répondre à des critères de compacité, d’isolation, de coût, etc. À titre d’illustration, un smartphone contient plusieurs antennes pour assurer des fonctions telles que la téléphonie, la navigation, la connexion à internet par WiFi, les liaisons Bluetooth, la technologie NFC (Near-Field Communications) et ce nombre tend à s’accroitre considérablement avec l’émergence de nouveaux services. Le même phénomène se retrouve également au niveau des plateformes aéroportées où des fonctions telles que la communication, la navigation, le radar, etc. sont utilisées. Cela conduit donc à la nécessité de réduire le nombre d’antennes en regroupant par exemple plusieurs fonctions au sein d’une même et unique antenne. Dans de précédents travaux de recherches, J. Euzière a démontré la possibilité de combiner une fonction radar et une seconde fonction (ici de communication) en utilisant un réseau de 16 monopoles initialement dédié au seul radar, grâce au Time Modulated Array (TMA). De cette façon, les deux fonctions utilisaient la même fréquence et étaient alimentées par une seule source. L’objectif principal de cette thèse est de proposer une solution d’antenne multifonction pour radar et communication encore plus compacte (constituée d’une seule antenne). L’idée est de partir d’une solution antennaire déjà existante et d’y apporter les modifications nécessaires à l’ajout d’une seconde fonction, sans pour autant augmenter la surface de l’antenne ni la complexité du système. / In order to respond to the increasingly demand of new services, the objects we use on a daily basis (such as mobile phones, cars, airplanes etc.), tend to integrate more and more radio systems while the space available is limited. These radio systems require the use of many antennas that must meet multiple requirements such as compactness, isolation, costs, etc. A smart-phone, for example, contains several antennas for global navigation satellite system (GNSS), WiFi, TV, FM radio, Bluetooth, near-field communications (NFC) and the number is expected to increase as new systems are added. Another example is in airborne platforms where multiple functions such as communication, navigation, radar, electronic warfare are used. This leads to the need of reducing the number of associated antennas by regrouping several radio functions into a single antenna. However, combining the functionality of several antennas into one shared radiating element while maintaining the functionality of the various radio systems presents a great challenge. During its Ph.D, J. Euzière demonstrated the possibility to combine a radar function and a secondary function from a 16-monopole array originally dedicated to radar operation by using Time Modulated Array (TMA) technique. By this way, the two functions were operating at the same frequency and the system was powered by a single source.The main objective of this thesis is to propose a more compact antenna (a single antenna) dedicated to radar and communication operations instead of using antenna array as J. Euzière did it. The idea is to start from an existing antenna solution and make the necessary modifications to add a second function without adding additional surface and complexity. As we are interested in radar applications, we will choose a directive antenna: a horn antenna. The goal is then to study the possibility to modify the radiation pattern of the horn antenna through controllable elements (slots) and to transmit a direct modulated signal at the antenna level for the communication function. Furthermore, polarization diversity is an attractive way to increase the isolation between two applications. Thus, this aspect will be taken into account in the design of the antenna solution.

A desirable goal in wireless communication systems is to achieve a high-rate data transmission through electrically small antennas. However, the overall transmission bandwidth is limited by the antenna size. As a well-known physical limitation, maximum achievable bandwidth of a small antenna is governed by the fundamental limit which defines a lower bound on the antenna quality factor. This limit is a function of electrical size of the antenna and therefore, as the antenna shrinks in size the bandwidth decreases as well. This dissertation presents a new technique to decouple the impedance bandwidth of a high-Q antenna from the information bandwidth in order to provide a wideband data-transmission. This technique controls the natural resonant frequencies of an electrically small antenna in a time-varying fashion such that ultra-fast frequency-shift keying modulation can be achieved regardless of the narrow bandwidth of the antenna. A major advantage of the proposed technique is that the high-Q property of a miniaturized antenna is a desirable design parameter rather than a limiting factor. Therefore, the antenna size can be reduced as much as required. It is shown that if the fundamental resonance of an antenna is shifted in time, the frequency of the near-zone fields which construct the reactive stored energy, changes momentarily and hence, the radiating fields track any instantaneous variation of the antenna fundamental resonance. This characteristic is utilized to employ a single-mode high-Q antenna in the transient state and modulate the fundamental resonant frequency according to the baseband data information. This approach leads to a new class of compact transmitters with a minimized architecture and high data-rate transmission capability. / Ph. D.

Cette thèse traite de synthétiseurs de fréquence, et plus précisément de diviseurs de fréquence fractionnaires qui sont des blocs critiques en radiocommunications. Une nouvelle méthode pour la division de fréquence fractionnaire y est présentée : Elle est basée sur la répartition aléatoire de l'erreur de phase. Deux implémentations de cette méthode sont proposées. Le spectre du bruit de phase en sortie de diviseur est débarrassé de toute raie parasite. L'énergie habituellement contenue dans ces raies étant uniformément répartie sur l'ensemble du spectre, ce dernier adopte un profil plat. La solution proposée peut être implémentée dans des synthétiseurs de fréquence tels que les Boucles à Verrouillage de Phase (PLL). Puisque aucune mise en forme du bruit n'est appliquée par le diviseur, la bande passante de la PLL peut être optimisée. Dans ces conditions, la possibilité d'une modulation directe haut débit de la PLL résultante est étudiée. Pour finir, des solutions d'optimisation du système résultant sont étudiées. / This dissertation deals with frequency synthesis and more specifically with the fractional frequency divider, one of the most critical blocks in radio frequency systems. A new fractional division method is presented along with two possible embodiments. It is based on a random dithering of the phase error. The divider output spectrum is cleaned from any fractional spurious tone. The spurious tones energy is uniformly spread on the whole spectrum, without noise shaping. The proposed solution can be implemented in frequency synthesizers like Phase Locked Loops (PLL). As no noise shaping is applied, the PLL bandwidth can be optimized. In this context, the possibility of high data-rate direct modulation is studied. Finally, solutions for the optimization of the resulting system are inspected.

This work consists of two main parts: i) Design and implementation of a compact current-reusing 2.4GHz direct-modulation transmitter with on-chip automatic tuning; ii) Design and implementation of a novel highly-reconfigurable, continuously tunable, power-adjustable Active-RC filter for multiple standards. The design, analysis, and experimental verification of a proposed self-calibrating, current reused 2.4GHz, direct-modulation transmitter are introduced. A stacked arrangement of the power amplifier/voltage-controlled oscillator is presented along with a novel LC-tank-tuning algorithm with a simple, low-cost, on-chip implementation. To transmit maximum power, the tuning loop ensures the PA's resonant tank is centered around the operating frequency, and the loop requires no ADC, DSP, or external signal generator. This work also details the proposed tuning-loop algorithm and examines the frequency-dependent nonlinear power-detector. The system was implemented in TSMC 0.18[mu]m CMOS, occupies 0.7 mm² (TX) + 0.1 mm² (self tuning), and was measured in a QFN48 package on FR4 PCB. Automatically adjusting the tank-tuning bits within their tuning range results in >4dB increase in output power. With the self-tuning circuit active, the transmitter delivers a measured output power of > 0dBm to a 100-[omega] differential load, and the system consumes 22.9 mA from a 2.2-V supply. A biquad design methodology and a baseband low-pass filter is presented for wireless and wireline applications with reconfigurable frequency response, selectable order (1st/3rd/5th), continuously tunable cutoff frequency (1MHz-20MHz) and adjustable power consumption (3mW-7.5mW). A discrete capacitor array coarsely tunes the low-pass filter, and a novel Continuous Impedance Multiplier (CIM) then finely tunes the filter. Resistive/capacitive networks select between the Chebyshev and Inverse Chebyshev approximation types. Also, a new stability metric for biquads, Minimum Acceptable Phase Margin (MAPM), is presented and discussed in the context of filter compensation and passband ripple considerations. Experimental results yield an IIP3 of 31.3dBm, a THD of -40dB at 447mV[subscript pk, diff] input signal amplitude, and a DR of 71.4dB. The filters tunable range covers frequencies from 1MHz to 20MHz. In Inverse Chebyshev mode, the filter achieves a passband group delay variation less than ±2:5%. The design is fabricated in 0.13[mu]m CMOS, occupies 1.53mm², and operates from a 1-V supply.

The diploma thesis Simulation of Multipath Propagation of Multistate Modulations is focused on the development of an appropriate algorithm in MATLAB environment, which is capable to simulate the impact of the multipath propagation on received signal (error rate) on the basis of given parameters of the transmission channels. Mechanisms and characteristics of the wave propagation in communication environment, types of digital modulations and their most important parameters are described in the first part of this thesis. The second part is focused on the simulation itself. Created GUI (Graphical User Interface) is able to display constellation diagrams of transmitted and received signals, as well as their bit error rate. It is also possible to compare these data with the data of signal, which is passed by a non-fading channel.

Cette thèse porte sur la conception, la réalisation et la caractérisation de diodes lasers de puissance, faible bruit à 1.5 µm sur InP pour des applications d’optique hyperfréquence, notamment pour des liaisons optiques analogiques de grande dynamique pour les systèmes radar. La première partie du travail a consisté à modéliser et concevoir des structures laser DFB ayant de faibles pertes internes. Ces structures, appelées lasers à semelle, incorporent une couche épaisse de matériaux entre la zone active et le substrat pour agrandir et délocaliser le mode propre optique des zones dopées p. La complexité de la conception résidait dans le bon compromis à trouver entre les performances statiques et dynamiques. Nous avons réalisé des diodes-lasers DFB avec une puissance > 150 mW, un rendement de 0.4 W/A, un niveau de bruit de 160 dB/Hz et une bande passante de modulation à 3 dB de 7.5 GHz. Les composants ont ensuite été caractérisés puis évalués dans des liaisons analogiques. Nous avons démontré des performances de gain de liaison, de dynamique et de point de compression à l’état de l’art mondial. En bande L (1-2 GHz) par exemple, nous avons montré des liaisons avec 0.5 dB de gain, un point de compression de 21 dBm et une dynamique (SFDR) de 122 dB.Hz2/3.En utilisant la même méthodologie de conception, la dernière partie du travail de thèse a été consacrée à la réalisation et à la caractérisation de lasers de puissance à verrouillage de modes pour la génération de train d’impulsions ultra-courts et la génération de peignes de fréquences. Ces structures présentent de très faibles largeurs de raie RF (550 Hz) et de très fortes puissances optiques (> 18 W en puissance crête). / This work focuses on the design, realization and characterization of high power, low noise 1.5 µm diode lasers for microwave applications and more particularly for high dynamic optical analog link for radar systems. The first part of this study deals with modeling and design of low internal losses DFB laser structures. These specific structures are called slab-coupled optical waveguide lasers, and are composed of a thick layer between the active layer and the substrate. The aim of this waveguide is to enlarge the optical eigenmode and to move the optical mode away from p-doped layers. The main difficulty was to find the good trade-off between laser static performances (optical power, efficiency) and dynamic performances (RIN and modulation bandwidth). We have succeeded in developing high efficiency (0.4 W/A), low noise (RIN ≈ 160 dB/Hz) DFB lasers with more than 150 mW and a 3 dB modulation bandwidth up to 7.5 GHz. We have then characterized our components on wide band and narrow band analog links. We have demonstrated state of the art gain links, dynamic and 1 dB compression power. In the L band (1-2 GHz) for example, we have obtained an optical link with a gain of 0.5 dB, a compression power of 21 dBm and a dynamic (SFDR) of 122 dB.Hz2/3.Finally we have applied the methodology and the design of slab-coupled optical waveguide structures to develop high power mode-locked lasers for ultra-short pulses generation and for optical and electrical comb generation. We have demonstrated narrow RF linewidth (550 Hz) lasers with very high power (continuous power > 400 mW and peak power > 18 W).