Una aproximación multinivel para el diseño sistemático de circuitos integrados de radiofrecuencia.

Tesis reducida por acuerdo de confidencialidad.En un mercado bien establecido como el de las telecomunicaciones, donde se está evolucionando hacia el 5G, se estima que hoy en día haya más de 2 Mil Millones de usuarios de Smartphones. Solo de por sí, este número es asombroso. Pero nada se compara a lo que va a pasar en un futuro muy próximo. El próximo boom tecnológico está directamente conectado con el mercado emergente del internet of things (IoT). Se estima que, en 2020, habrá 20 Mil Millones de dispositivos físicos conectados y comunicando entre sí, lo que equivale a 4 dispositivos físicos por cada persona del planeta. Debido a este boom tecnológico, van a surgir nuevas e interesantes oportunidades de inversión e investigación. De hecho, se estima que en 2020 se van a invertir cerca de 3 Mil Millones de dólares solo en este mercado, un 50% más que en 2017. Todos estos dispositivos IoT tienen que comunicarse inalámbricamente entre sí, algo en lo que los circuitos de radiofrecuencia (RF) son imprescindibles. El problema es que el diseño de circuitos RF en tecnologías nanométricas se está haciendo extraordinariamente difícil debido a su creciente complejidad. Este hecho, combinado con los críticos compromisos entre las prestaciones de estos circuitos, tales como el consumo de energía, el área de chip, la fiabilidad de los chips, etc., provocan una reducción en la productividad en su diseño, algo que supone un problema debido a las estrictas restricciones time-to-market de las empresas. Es posible concluir, por tanto, que uno de los ámbitos en los que es tremendamente importante centrarse hoy en día, es el desarrollo de nuevas metodologías de diseño de circuitos RF que permitan al diseñador obtener circuitos que cumplan con especificaciones muy exigentes en un tiempo razonable. Debido a las complejas relaciones entre prestaciones de los circuitos RF (por ejemplo, ruido de fase frente a consumo de potencia en un oscilador controlado por tensión), es fácil comprender que el diseño de circuitos RF es una tarea extremadamente complicada y debe ser soportada por herramientas de diseño asistido por ordenador (EDA). En un escenario ideal, los diseñadores tendrían una herramienta EDA que podría generar automáticamente un circuito integrado (IC), algo definido en la literatura como un compilador de silicio. Con esta herramienta ideal, el usuario sólo estipularía las especificaciones deseadas para su sistema y la herramienta generaría automáticamente el diseño del IC listo para fabricar (lo que se denomina diseño físico o layout). Sin embargo, para sistemas complejos tales como circuitos RF, dicha herramienta no existe. La tesis que se presenta, se centra exactamente en el desarrollo de nuevas metodologías de diseño capaces de mejorar el estado del arte y acortar la brecha de productividad existente en el diseño de circuitos RF. Por lo tanto, con el fin de establecer una nueva metodología de diseño para sistemas RF, se han de abordar distintos cuellos de botella del diseño RF con el fin de diseñar con éxito dichos circuitos. El diseño de circuitos RF ha seguido tradicionalmente una estrategia basada en ecuaciones analíticas derivadas específicamente para cada circuito y que exige una gran experiencia del diseñador. Esto significa que el diseñador plantea una estrategia para diseñar el circuito manualmente y, tras varias iteraciones, normalmente logra que el circuito cumpla con las especificaciones deseadas. No obstante, conseguir diseños con prestaciones óptimas puede ser muy difícil utilizando esta metodología, ya que el espacio de diseño (o búsqueda) es enorme (decenas de variables de diseño con cientos de combinaciones diferentes). Aunque el diseñador llegue a una solución que cumpla todas las especificaciones, nunca estará seguro de que el diseño al que ha llegado es el mejor (por ejemplo, el que consuma menos energía). Hoy en día, las técnicas basadas en optimización se están utilizando con el objetivo de ayudar al diseñador a encontrar automáticamente zonas óptimas de diseño. El uso de metodologías basadas en optimización intenta superar las limitaciones de metodologías previas mediante el uso de algoritmos que son capaces de realizar una amplia exploración del espacio de diseño para encontrar diseños de prestaciones óptimas. La filosofía de estas metodologías es que el diseñador elige las especificaciones del circuito, selecciona la topología y ejecuta una optimización que devuelve el valor de cada componente del circuito óptimo (por ejemplo, anchos y longitudes de los transistores) de forma automática. Además, mediante el uso de estos algoritmos, la exploración del espacio de diseño permite estudiar los distintos y complejos compromisos entre prestaciones de los circuitos de RF. Sin embargo, la problemática del diseño de RF es mucho más amplia que la selección del tamaño de cada componente. Con el objetivo de conseguir algo similar a un compilador de silicio para circuitos RF, la metodología desarrollada en la tesis, tiene que ser capaz de asegurar un diseño robusto que permita al diseñador tener éxito frente a medidas experimentales, y, además, las optimizaciones tienen que ser elaboradas en tiempos razonables para que se puedan cumplir las estrictas restricciones time-to-market de las empresas. Para conseguir esto, en esta tesis, hay cuatro aspectos clave que son abordados en la metodología: 1. Los inductores integrados todavía son un cuello de botella en circuitos RF. Los parásitos que aparecen a altas frecuencias hacen que las prestaciones de los inductores sean muy difíciles de modelar. Existe, por tanto, la necesidad de desarrollar nuevos modelos más precisos, pero también muy eficientes computacionalmente que puedan ser incluidos en metodologías que usen algoritmos de optimización. 2. Las variaciones de proceso son fenómenos que afectan mucho las tecnologías nanométricas, así que para obtener un diseño robusto es necesario tener en cuenta estas variaciones durante la optimización. 3. En las metodologías de diseño manual, los parásitos de layout normalmente no se tienen en cuenta en una primera fase de diseño. En ese sentido, cuando el diseñador pasa del diseño topológico al diseño físico, puede que su circuito deje de cumplir con las especificaciones. Estas consideraciones físicas del circuito deben ser tenidas en cuenta en las primeras etapas de diseño. Por lo tanto, con el fin de abordar este problema, la metodología desarrollada tiene que tener en cuenta los parásitos de la realización física desde una primera fase de optimización. 4. Una vez se ha desarrollado la capacidad de generar distintos circuitos RF de forma automática utilizando esta metodología (amplificadores de bajo ruido, osciladores controlados por tensión y mezcladores), en la tesis se aborda también la composición de un sistema RF con una aproximación multinivel, donde el proceso empieza por el diseño de los componentes pasivos y termina componiendo distintos circuitos, construyendo un sistema (por ejemplo, un receptor de radiofrecuencia). La tesis aborda los cuatro problemas descritos anteriormente con éxito, y ha avanzado considerablemente en el estado del arte de metodologías de diseño automáticas/sistemáticas para circuitos RF.Premio Extraordinario de Doctorado U

Microwave Integrated Circuits Design with Relational Induction Neural Network

The automation design of microwave integrated circuits (MWIC) has long been viewed as a fundamental challenge for artificial intelligence owing to its larger solution space and structural complexity than Go. Here, we developed a novel artificial agent, termed Relational Induction Neural Network, that can lead to an automotive design of MWIC and avoid brute-force computing to examine every possible solution, which is a significant breakthrough in the field of electronics. Through the experiments on microwave transmission line circuit, filter circuit and antenna circuit design tasks, strongly competitive results are obtained respectively. Compared with the traditional reinforcement learning method, the learning curve shows that the proposed architecture is able to quickly converge to the pre-designed MWIC model and the convergence rate is up to four orders of magnitude. This is the first study which has been shown that an agent through training or learning to automatically induct the relationship between MWIC's structures without incorporating any of the additional prior knowledge. Notably, the relationship can be explained in terms of the MWIC theory and electromagnetic field distribution. Our work bridges the divide between artificial intelligence and MWIC and can extend to mechanical wave, mechanics and other related fields

A parametric study on the effects of the variations in line width on the circuit model parameters of a planar spiral inductor on GaAs

The increasing demands for low cost radio frequency integrated circuits (RFIC’s) has generated great attention in on-chip passive components. A spiral inductor is an important passive component for many radio frequency circuits such as low noise amplifiers, mixers, switches, and voltage controlled oscillators. Considerable effort has gone into the design and modeling of the spiral inductor, however, very little research has investigated the effects due to the errors introduced into the spiral inductor modeling. This research investigates the effects of variations in conductor line width on equivalent circuit model of planar rectangular spiral inductors. A parametric study is performed where a full wave electromagnetic simulator, Sonnet TM, is used to simulate several sets of inductors on Gallium Arsenide (GaAs) substrate having different dimensions. The scattering parameters of a particular inductor were simulated over the desired frequency range. These simulated scattering parameters are used to extract the equivalent circuit model parameters using optimization process. The extracted inductor model parameters are validated through the existing physics based formulae. the simulation results reveals that variations in the conductor line width affect every parameters in the equivalent circuit model of the inductor i.e. the series inductance, the series resistance, the capacitance between the inductor turns. Change in series inductance due to the variations in the conductor line width is nearly a linear function of the nominal inductance. Variation in series resistance is an exponential function of nominal conductor width. Change in line to line capacitance due to variations in conductor line width is an exponential function of nominal spacing between conductors. Finally, variations in conductor line width have no or little effects on substrate capacitance. Curve fitting techniques are utilized to extract simple equations useful for estimating the changes in the circuit model parameters with respect to the variation in conductor line width. These equations advantageous to the RFIC’s designer since the inductor equivalent circuit model parameters can easily be modified to account for variations in conductor line width and also they can be used during circuit design optimization to explore inductor space

Methods and tools for the design of RFICs

Ambient intelligence is going to focus the next advances in wireless technologies. Hence, the increasing demand on radio frequency (RF) devices and applications represents, not only a challenge for technological industries to improve its roadmaps, but also for RF engineers to design more robust, low-power, small-size and low-cost devices. Regarding to communication robustness, in the latest years, differential topologies have acquired an important relevance because of its natural noise and interference immunity. Within this framework, a differential n-port device can still be treated with the classical analysis circuit theory by means of Z-,Y-, h-parameters or the most suitable S-parameters in the radio frequency field. Despite of it, Bockelman introduced the mixed-mode scattering parameters, which more properly express the differential and common-mode behavior of symmetrical devices. Since then, such parameters have been used with a varying degree of success, as it will be shown, mainly because of a misinterpretation. Thereby, this thesis is devoted to extend the theory of mixed-mode scattering parameters and proposes the methodology to analyze such devices. For this proposal, the simplest case of a two-port device is developed. By solving this simple case, most of the lacks of the current theory are filled up. As instance, it allows the characterization and comparison of symmetric and spiral inductors, which have remained a controversy point until now. After solving this case, the theory is extended to a n-port device. Another key point on the fast and inexpensive development of radio frequency devices is the advance on fast CAD tools for the analysis and synthesis of passive devices. In the case of silicon technologies, planar inductors have become the most popular shapes because of its integrability. However, the design of inductors entails a deep experience and acknowledge not only on the behavior of such devices but on the use of electromagnetic (EM) simulators. Unfortunately, the use of EM simulators consumes an important quantity of time and resources. Thereby, this thesis is devoted to improve some of the aspects that slow down the synthesis process of inductors. Therefore, an ‘ab initio’ technique for the meshing of planar radio frequency and microwave circuits is described. The technique presented can evaluate the losses in the component with a high accuracy just in few seconds where an electromagnetic simulator would normally last hours. Likewise, a simple bisection algorithm for the synthesis of compact planar inductors is presented. It is based on a set of heuristic rules obtained from the study of the electromagnetic behavior of these planar devices. Additionally, design of a single-ended to differential low noise amplifier (LNA) in a CMOS technology is performed by using the methods and tools described.L'enginyeria de radiofreqüència i la tecnologia de microones han assolit un desenvolupament inimaginable i avui en dia formen part de la majoria de les nostres activitats diàries. Probablement, la tecnologia mòbil ha tingut un desenvolupament més ràpid que qualsevol altre avenç tecnològic de l'era digital. Avui en dia, podem dir que el paradigma de la mobilitat s'ha assolit i tenim accés ràpid a internet des de qualsevol lloc on podem estar amb un dispositiu de butxaca. No obstant això, encara hi ha fites per endavant. Es més que probable que el paradigma de l’ "ambient intelligence” sigui el centre dels pròxims avenços en les tecnologies sense fils. A diferencia del paradigma de l"ambient intelligence', l'evolució de la tecnologia de la informació mai ha tingut l'objectiu explícit de canviar la societat, sinó que ho van fer com un efecte secundari, en canvi, les visions d' “ambient intelligence” proposen expressament el transformar la societat mitjançant la connexió completa i la seva informatització. Per tant, l'augment de la demanda de dispositius de ràdio freqüència (RF) i de les seves possibles aplicacions representa, no només un repte per a les indústries tecnològiques per millorar els seus plans de treball, sinó també per als enginyers de RF que hauran de dissenyar dispositius de baixa potència, més robusts, de mida petita i de baix cost. Quant a la robustesa dels dispositius, en els últims anys, les topologies de tipus diferencial han adquirit una important rellevància per la seva immunitat natural al soroll i resistència a les interferències. Dins d'aquest marc, un dispositiu de nports diferencial, encara pot ser tractat com un dispositiu 2nx2n i la teoria clàssica d'anàlisi de circuits (és a dir, la temia de quadripols) es pot aplicar a través de paràmetres Z, Y, h o els paràmetres S, més adequats en el camp de freqüència de ràdio. Tot i això, Bockelman i Eisenstadt introdueixen els paràmetres S mixtos, que expressen més adequadament el comportament diferencial i en mode comú de dispositius simètrics o asimètrics. Des de llavors, aquests paràmetres s'han utilitzat amb un grau variable d'èxit, com es mostrarà, principalment a causa d'una mala interpretació. D'aquesta manera, la primera part d'aquesta tesi està dedicada a estendre la teoria dels paràmetres S de mode mixt i proposa la metodologia d'anàlisi d'aquest tipus de dispositius i circuits. D'aquesta forma, en el Capítol 2, es desenvolupa el cas més simple d'un dispositiu de dos ports. En resoldre aquest cas simple, la major part de les mancances de la teoria actual es posen de relleu. Com a exemple, pennet la caracterització i la comparació de bobines simètriques i espiral no simètriques, que han estat un punt de controvèrsia fins ara. Després de resoldre aquest cas, al Capítol 3 s'estén la teOIia a un dispositiu de n-ports dels quals un nombre pot ser single-ended i la resta diferencials. És en aquest moment quan la dualitat existent entre els paràmetres S estàndard i de mode mixt es pot veure clarament i es destaca en el seu conjunt. Aquesta teoria permet, tanmateix, estendre la teoria clàssica d'amplificadors quan s'analitzen per mitjà de paràmetres S. Un altre punt clau en el desenvolupament ràpid i de baix cost dels dispositius de radiofreqüència és l'avenç en les eines CAD ràpides per a l'anàlisi i síntesi dels dispositius passius, en especial dels inductors. Aquests dispositius apareixen tot sovint en el disseny de radio freqüència degut a la seva gran versatilitat. Tot i que hi ha hagut múltiples intents de reemplaçar amb components externs o circuits, fins i tot actius, en el cas de les tecnologies de silici, els inductors planars s'han convertit en les formes més populars per la seva integrabilitat. No obstant això, el disseny d'inductors implica conèixer i posseir una experiència profunda no només en el comportament d'aquests dispositius, però també en l'ús de simuladors electromagnètics (EM). Desafortunadament, l'ús dels simuladors EM consumeix una quantitat important de temps i recursos. Per tant, la síntesi dels inductors representa un important inconvenient actualment. D'aquesta manera, la segona part d'aquesta tesi està dedicada a millorar alguns dels aspectes que frenen el procés de síntesi dels inductors. Per tant, en el Capítol 4, es descriu una tècnica 'ab initio' de generació de la malla per bobines planars en ràdio freqüència i microones. La tècnica es basa en l'estudi analític dels fenòmens d'aglomeració de corrent que tenen lloc a l'interior del component. En aquesta avaluació, no es requereix una solució explícita dels corrents i de les càrregues arreu del circuit. Llavors, el nombre de cel•les de la malla assignades a una tira de metall donada, depèn del valor inicialment obtingut a partir de l'estudi analític. La tècnica presentada pot avaluar les pèrdues en el component amb una gran precisió només en uns pocs segons, quan comparat amb un simulador electromagnètic normalment es necessitaria hores. De la mateixa manera, en el Capítol 5 es presenta un senzill algoritme de bisecció per a la síntesi d'inductors planars compactes. Es basa en un conjunt de regles heurístiques obtingut a partir de l'estudi del comportament electromagnètic d'aquests dispositius planars. D'aquesta manera, el nombre d'iteracions es manté moderadament baix.D'altra banda, per tal d'accelerar l'anàlisi en cada pas, s'utilitza un simulador ràpid electromagnètic planar, el qual es basa en el coneixement que es té del component sintetitzat. Finalment, en el Capítol 6, la metodologia de paràmetres S de mode mixt proposada i les eines CAD introduides s'utilitzen àmpliament en el disseny d'un amplificador de baix soroll “single-ended” a diferencial (LNA), mitjançant una tecnologia estàndard CMOS.L'amplificador de baix soroll és un dels components claus en un sistema de recepció de radio freqüència, ja que tendeix a dominar la sensibilitat i la figura de soroll (NF) de tot el sistema. D'altra banda, les característiques d'aquest circuit estan directament relacionades amb els components actius i passius disponibles en una tecnologia donada. Per tant, la tecnologia escollida, el factor de qualitat dels passius, i la forma com es caracteritzen tindran un alt impacte en les principals figures de mèrit del circuit real

A parametric study on the effects of the variations in line width on the circuit model parameters of a planar spiral inductor on GaAs

The increasing demands for low cost radio frequency integrated circuits (RFIC’s) has generated great attention in on-chip passive components. A spiral inductor is an important passive component for many radio frequency circuits such as low noise amplifiers, mixers, switches, and voltage controlled oscillators. Considerable effort has gone into the design and modeling of the spiral inductor, however, very little research has investigated the effects due to the errors introduced into the spiral inductor modeling. This research investigates the effects of variations in conductor line width on equivalent circuit model of planar rectangular spiral inductors. A parametric study is performed where a full wave electromagnetic simulator, Sonnet TM, is used to simulate several sets of inductors on Gallium Arsenide (GaAs) substrate having different dimensions. The scattering parameters of a particular inductor were simulated over the desired frequency range. These simulated scattering parameters are used to extract the equivalent circuit model parameters using optimization process. The extracted inductor model parameters are validated through the existing physics based formulae. the simulation results reveals that variations in the conductor line width affect every parameters in the equivalent circuit model of the inductor i.e. the series inductance, the series resistance, the capacitance between the inductor turns. Change in series inductance due to the variations in the conductor line width is nearly a linear function of the nominal inductance. Variation in series resistance is an exponential function of nominal conductor width. Change in line to line capacitance due to variations in conductor line width is an exponential function of nominal spacing between conductors. Finally, variations in conductor line width have no or little effects on substrate capacitance. Curve fitting techniques are utilized to extract simple equations useful for estimating the changes in the circuit model parameters with respect to the variation in conductor line width. These equations advantageous to the RFIC’s designer since the inductor equivalent circuit model parameters can easily be modified to account for variations in conductor line width and also they can be used during circuit design optimization to explore inductor space

Integrated Voltage Regulators with Thin-Film Magnetic Power Inductors

Integration of alternative materials and devices with CMOS will expand functionality and improve performance of established applications in the era of diminishing returns from Moore's Law scaling. In particular, integration of thin-film magnetic materials will enable improvements in energy efficiency of digital computing applications by enabling integrated power conversion and management with on-chip power inductors. Integrated voltage reg- ulators will also enable fine-grained power management, by providing dynamic scaling of the supply voltage in concert with the clock frequency of synchronous logic to throttle power consumption at periods of low computational demand. Implementation of integrated power conversion requires high capacity energy storage devices. This is best achieved with integration of thin-film magnetic materials for high quality on-chip power inductors. This thesis describes a body of work conducted to develop integrated switch-mode voltage regulators with thin-film magnetic power inductors. Soft-magnetic materials and inductor topologies are selected and optimized, with intent to maximize efficiency and current density of the integrated regulators. Custom integrated circuits are designed and fabricated in 45nm-SOI to provide the control system and power-train necessary to drive the power inductors. A silicon interposer is designed and fabricated in collaboration with IBM Research to integrate custom power inductors by 2.5D chip stacking, enabling power conversion with current density greater than 10A/mm2. The concepts and designs developed from this work will enable significant improvements in performance-per-watt of future microprocessors

Power Quality

Electrical power is becoming one of the most dominant factors in our society. Power generation, transmission, distribution and usage are undergoing signifi cant changes that will aff ect the electrical quality and performance needs of our 21st century industry. One major aspect of electrical power is its quality and stability – or so called Power Quality. The view on Power Quality did change over the past few years. It seems that Power Quality is becoming a more important term in the academic world dealing with electrical power, and it is becoming more visible in all areas of commerce and industry, because of the ever increasing industry automation using sensitive electrical equipment on one hand and due to the dramatic change of our global electrical infrastructure on the other. For the past century, grid stability was maintained with a limited amount of major generators that have a large amount of rotational inertia. And the rate of change of phase angle is slow. Unfortunately, this does not work anymore with renewable energy sources adding their share to the grid like wind turbines or PV modules. Although the basic idea to use renewable energies is great and will be our path into the next century, it comes with a curse for the power grid as power fl ow stability will suff er. It is not only the source side that is about to change. We have also seen signifi cant changes on the load side as well. Industry is using machines and electrical products such as AC drives or PLCs that are sensitive to the slightest change of power quality, and we at home use more and more electrical products with switching power supplies or starting to plug in our electric cars to charge batt eries. In addition, many of us have begun installing our own distributed generation systems on our rooft ops using the latest solar panels. So we did look for a way to address this severe impact on our distribution network. To match supply and demand, we are about to create a new, intelligent and self-healing electric power infrastructure. The Smart Grid. The basic idea is to maintain the necessary balance between generators and loads on a grid. In other words, to make sure we have a good grid balance at all times. But the key question that you should ask yourself is: Does it also improve Power Quality? Probably not! Further on, the way how Power Quality is measured is going to be changed. Traditionally, each country had its own Power Quality standards and defi ned its own power quality instrument requirements. But more and more international harmonization efforts can be seen. Such as IEC 61000-4-30, which is an excellent standard that ensures that all compliant power quality instruments, regardless of manufacturer, will produce of measurement instruments so that they can also be used in volume applications and even directly embedded into sensitive loads. But work still has to be done. We still use Power Quality standards that have been writt en decades ago and don’t match today’s technology any more, such as fl icker standards that use parameters that have been defi ned by the behavior of 60-watt incandescent light bulbs, which are becoming extinct. Almost all experts are in agreement - although we will see an improvement in metering and control of the power fl ow, Power Quality will suff er. This book will give an overview of how power quality might impact our lives today and tomorrow, introduce new ways to monitor power quality and inform us about interesting possibilities to mitigate power quality problems. Regardless of any enhancements of the power grid, “Power Quality is just compatibility” like my good old friend and teacher Alex McEachern used to say. Power Quality will always remain an economic compromise between supply and load. The power available on the grid must be suffi ciently clean for the loads to operate correctly, and the loads must be suffi ciently strong to tolerate normal disturbances on the grid

Solid State Circuits Technologies

The evolution of solid-state circuit technology has a long history within a relatively short period of time. This technology has lead to the modern information society that connects us and tools, a large market, and many types of products and applications. The solid-state circuit technology continuously evolves via breakthroughs and improvements every year. This book is devoted to review and present novel approaches for some of the main issues involved in this exciting and vigorous technology. The book is composed of 22 chapters, written by authors coming from 30 different institutions located in 12 different countries throughout the Americas, Asia and Europe. Thus, reflecting the wide international contribution to the book. The broad range of subjects presented in the book offers a general overview of the main issues in modern solid-state circuit technology. Furthermore, the book offers an in depth analysis on specific subjects for specialists. We believe the book is of great scientific and educational value for many readers. I am profoundly indebted to the support provided by all of those involved in the work. First and foremost I would like to acknowledge and thank the authors who worked hard and generously agreed to share their results and knowledge. Second I would like to express my gratitude to the Intech team that invited me to edit the book and give me their full support and a fruitful experience while working together to combine this book