Exploration of Nonlinear Devices and Nonlinear Transmission Line Techniques for Microwaves Applications

RESUME Les systemes de communication modernes dependent fortement des circuits non lineaires, tels que les amplificateurs de puissance (PA), les melangeurs, les multiplicateurs, les oscillateurs, les commutateurs, etc., qui sont construits a partir de composants non lineaires passifs (comme des diodes) ou actifs (par exemple des transistors). Cette these etudie les dispositifs non lineaires passifs traditionnels et emergents, ainsi que les techniques de lignes de transmission non lineaires (NLTL). Plusieurs de leurs applications micro-ondes ont egalement ete etudiees, y compris la recuperation d'energie sans fil, la synthese d’impedance electronique et l’adaptation d’impedance bidimensionnelle (inductive et capacitive). Dans le chapitre 1, sont d'abord etudies les dispositifs non lineaires traditionnels resistifs, capacitifs et inductifs. Les dispositifs non lineaires emergents, y compris les dispositifs MEMS et la spindiode, sont ensuite explores. La construction physique de base, les principes de fonctionnement, ainsi que les caracteristiques et applications pour divers types de dispositifs non lineaires sont expliques et compares. Les lignes de transmission non-lineaires (NLTL) traditionnelles utilisant des dispositifs non lineaires capacitifs (varactor, BST etc.) ou inductifs (ferrite saturee), et la technique hybride NLTL emergente utilisant a la fois des dispositifs non lineaires capacitifs et inductifs sont egalement etudiees. Le chapitre 2 examine les techniques de conversion d'energie micro-ondes a courant-continu de faible puissance a la fine pointe de la technologie. Une image complete de l'etat de l'art sur cet aspect est donnee graphiquement. Elle compare differentes technologies telles que le transistor, la diode et les technologies CMOS. Depuis le tout debut des techniques integrees RF et micro-ondes et de la recuperation d'energie, les diodes Schottky ont ete le plus souvent utilisees dans les circuits de melange et de redressement. Cependant, dans des applications specifiques de recuperation d'energie, la technique des diodes Schottky ne parvient pas a fournir une efficacite satisfaisante de conversion RF-dc. Suite aux limitations mises en evidence des dispositifs actuels, ce travail introduit, pour la premiere fois, un composant non lineaire pour une redressement de faible puissance, base sur une decouverte recente en spintronique, a savoir, la jonction tunnel magnetique, parfois appelee spindiode. Un modele equivalent de spindiode est developpe pour decrire le comportement en frequence.----------ABSTRACT Modern communication systems are heavily dependent on nonlinear circuits, such as PA, mixer, multiplier, oscillator, switch, etc., the core of which are either passive nonlinear elements and devices (e.g. diodes) or active nonlinear components and devices (e.g. transistors). This thesis aims at investigating a number of traditional and emerging passive nonlinear devices and nonlinear transmission line (NLTL) techniques, and developing four of their microwave applications such as wireless power harvesting, electronic impedance synthesizer, and two-dimensional tuning circuit. In Chapter 1, traditional nonlinear devices in terms of the categories of resistive, capacitive and inductive are firstly investigated. Emerging nonlinear devices including microelectromechanical system (MEMS) devices and spindiodes are then explored. The basic physical constructions, operation principles, and characteristics as well as applications of various types of nonlinear devices are explained and compared. Traditional NLTL techniques make use of either capacitive nonlinear devices (varactor, BST etc.) or inductive nonlinear devices (saturated ferrite), and emerging hybrid NLTL techniques are also studied through the deployment of both nonlinear capacitive and inductive devices. Chapter 2 examines the state-of-the-art low-power microwave-to-dc energy conversion techniques. A comprehensive picture of the state-of-the-art on this aspect is given graphically, which compares different technologies such as transistor, diode, and CMOS schemes. Since the very beginning of RF and microwave integrated techniques and energy harvesting, Schottky diodes as the undisputable dominant choice, have been widely used in mixing and rectifying circuits. However, in specific μW power-harvesting applications, the Schottky diode technique seemingly fails to provide a satisfactory RF–dc conversion. Subsequent to the highlighted limitations of current devices, this work introduces, for the first time, a nonlinear component for low-power rectification based on a recent discovery in spintronics, namely, the Magnetic Tunnel Junction, also called spindiode. An equivalent model of spindiode is developed to describe the frequency behavior. Full parametric studies show that the interfacial capacitance, rather than the geometric capacitance, as it is usually the case for diode, plays a crucial role in the drop of efficiency in microwave frequency applications.