<p>Recent advances in electromagnetics introduced tools that enable the creation of arti-</p><p>cial electromagnetic structures with exotic properties such as negative material pa-</p><p>rameters. The ability to express these parameters has experimentally demonstrated</p><p>using passive metamaterial structures. These structures, based on their passivity and</p><p>resonant properties, are typically associated with high loss and signicant bandwidth</p><p>limitations.</p><p>Enhancing and further exploring novel electromagnetic properties can be done</p><p>through embedding active circuits in the constitutive unit cells. Active elements</p><p>are able to supplement the passive inclusions to mitigate and overcome loss and</p><p>bandwidth limitations. The inclusion of these circuits also signcantly expands the</p><p>design space for the development of functional metamaterials and their potential</p><p>applications.</p><p>Due to the relative diculty of designing active circuits compared with passive</p><p>circuits, using active circuits in the construction of metamaterials is still an under-</p><p>developed area of research. By combining the two elds of active circuit design and</p><p>metamaterial design, we aim ll the functional active metamaterial design space.</p><p>This document provides the basis for understanding the design and synthesis of</p><p>functional active metamaterials.</p><p>To provide necessary background matter, chapter 1 will function as an introduc-</p><p>tion chapter, discussing how active electromagnetic metamaterials are created and characterized. There are also several required design techniques necessary to suc-</p><p>cessfully engineer a functional active metamaterial. The introduction will emphasize</p><p>on linking metamaterial unit cell response with RF/analog circuit design with a brief</p><p>introduction to the semiconductor physics important to aid in the understanding of</p><p>the full active metamaterial design and fabrication process.</p><p>The subsequent chapters detail our specic contributions to the eld of func-</p><p>tional active RF metamaterials. Chapter 2 introduces and characterizes a meta-</p><p>material designed to have a tunable quality factor (tunable resonant bandwidth).</p><p>This metamaterial is essentially passive but demonstrates the transistor's versatility</p><p>as a combination of tunable elements, motivating the use of embedding transistors</p><p>in metamaterials. After establishing a simple application of a transistor in a pas-</p><p>sive metamaterial, chapter 3 outlines the design and characterization of an active</p><p>metamaterial exhibiting the properties of loss cancellation and gain. Chapter 4 in-</p><p>troduces another active metamaterial with the ability to self-adapt to an incident</p><p>signal. Within the self-adapting system, several complex RF circuit systems are</p><p>simulatenously developed and implemented such as a self-oscillating mixer and a</p><p>phase locked loop. Conclusions and additional suggested future research directions</p><p>are discussed in chapter 5.</p><p>There are also several appendices attached at the end of this document that are</p><p>meant to assist future graduate students and other readers. The additional topics</p><p>include the experimental verication of a passive magnetic metamaterial acting as a</p><p>near eld parasitic, the stabilization and measurement of a tunnel diode, a discussion</p><p>on the challenges of realizing active inductors from discrete components, and a basic</p><p>strategy for creating a non-volatile metamaterial. It is my aim for these appendices</p><p>to help provide additional inspiration for future studies within the eld.</p> / Dissertation

FDTD is a numerical method that uses the second-order central-difference method to discrete the Maxwell¡¦s equations in differential form, and positioning electromagnetic field in space grids and time grids. It is applied to analyze many electromagnetic problems in time domain. In this report the FDTD method is extended to include lumped-elements (as resistor, inductor, capacity),and nonlinear elements(as diode, transistor) to combine the circuit elements and electromagnetic fields, it¡¦s so called LE-FDTD algorithm. The first, we will introduce the theory derivations and simulate some circuit structures in 2D, and then in order to simulate the real circuits, we will extend this algorithm in 3D to make full-wave analysis.

The design of an analog frontend including a receiver amplifier (RX) and laser diode driver (LDD) for optical communication system is described. The RX consists of a transimpedance amplifier, a limiting amplifier, and an output buffer (BUF). An offset compensation and common-mode control circuit is designed using switched-capacitor technique to save chip area, provides continuous reduction of the offset in the RX. Active-peaking methods are used to enhance the bandwidth and gain. The very low gate-oxide breakdown voltage of transistors in deep sub-micron technologies is overcome in the LDD by implementing a topology which has the amplifier placed in a floating well. It comprises a level shifter, a pre-amplifier, and the driver stage. The single-chip frontend, fabricated in a 28 nm bulk-digital complementary metal–oxide–semiconductor (CMOS) process has a total active area of 0.003 mm² , is among the smallest optical frontends. Without the BUF, which consumes 8 mW from a separate supply, the RX power consumption is 21 mW, while the LDD consumes 32 mW. Small-signal gain and bandwidth are measured. A photo diode and laser diode are bonded to the chip on a test-printed circuit board. Electro-optical measurements show an error-free detection with a bit error rate of 10⁻¹² at 20 Gbit/s of the RX at and a 25 Gbit/s transmission of the LDD.

En la presente tesis se muestra una nueva metodología de extracción "inteligente" de modelos circuitales lineales y no lineales para dispositivos MESFET y HEMT, además de efectuar numerosas aportaciones en el campo de las medidas radioeléctricas de dichos dispositivos mediante diseño del hardware y del software necesario para la automatización de las mismas. Por otro lado se presenta un novedoso modelo de Gran Señal para dispositivos HEMT de potencia que da cuenta del fenómeno de la compresión de la transconductancia y es fácilmente implementable en simuladores no lineales comerciales del tipo de MDS, LIBRA, HARMONICA, etc. Además se ha aumentado el rango de validez frecuencial de los modelos de pequeña señal mediante la obtención de las expresiones "exactas" de los modelos usuales de pequeña señal Vendelin-Dambrine, Vickes, Berroth & Bosch, etc. Otra novedad aportada por este trabajo de tesis ha sido aplicar estos modelos lineales a los transistores HEMT, evitando la obtención valores carentes de significado físico como ocurría hasta ahora. Como validación del modelo no lineal de HEMT se han llevado a cabo numerosas simulaciones del mismo en MDS que han sido comparadas con las medidas experimentales realizadas en nuestro laboratorio (Scattering, DC, Pulsadas y Pin/Pout) poniendo de manifiesto la exactitud del modelo. Para validar los modelos de pequeña señal se han efectuado simulaciones con el simulador lineal MMICAD utilizando transistores de diferentes tamaños procedentes de distintas foundries con objeto de visualizar el comportamiento del dispositivo independientemente del origen del mismo. / In this thesis a new methodology for the "intelligent" parameter extraction of linear and non-linear model for GaAs MESFET and HEMT devices is shown, besides numerous contributions in the field of Scattering and DC measurements of this kind of devices by means of hardware design and necessary software for the automation of the same have been done. On the other hand a novel Great Signal model for HEMT devices is presented. This model is capable to model the transconductance compression phenomenon and it is easily to built in commercial non-linear simulators like MDS, LIBRA, Microwave HARMONICA, etc. This work has also increased the frequency range for the usual small-signal models by means of calculate "exact" expressions of them. Another novelty contribution of this thesis is to apply for first time these linear models to HEMT transistors, avoiding the lacking of physical meaning values like it occurred up to now. To make possible the validation of non-linear HEMT model, simulations with MDS software and comparisons with experimental measurements made in our laboratory (Scattering, DC, Pulsed and Pin/ Pout) have been carried out and there was very good agreement between measured and simulated data. To validate small-signal models referred before, simulations with MMICAD software and comparisons between simulated and experimental scattering measurements using transistors of different sizes from several foundries and technological processes have been made.