Efficient Low Power Headphone Driver

In recent years, the consumer electronics market for battery-powered devices such as smartphones and tablets has been rapidly expanding. The requirements for audio CODEC in these portable devices have extended from merely supporting voice calls to high-fidelity music playback. As a result, audio driver performance has become one of the most important differentiating factors among products from different suppliers. There are three basic performance metrics that are typically used to benchmark audio modules: the maximum delivered output power, the audio fidelity measured in terms of dynamic range, THD+N, and finally the battery life. Maximizing all three of these performance metrics has proven to be an exceptionally hard task as portrayed by the research publications.This work presents an attempt to push all three of these metrics together and provide an acceptable balance which is achieved by selecting the right topology. Conventionally, headphone drivers are designed using a linear amplifier topology for many reasons- most prominently- to achieve a superior THD+N and PSRR requirement which in the past was essentially the only key performance metric needed. This came at the expense of realizing mediocre power efficiency targets, thereby wasting battery life. This picture changed dramatically over the last decade with smartphones and other portable devices becoming the first choice of the young generation. These devices are extremely power hungry due to the unlimited functions and features they provide and therefore battery life has come to the spotlight as a key resource that need to be preserved. As a result, in this work a headphone driver is based on a switching topology that is able to deliver more than 230mW of power (or equivalently 2Vrms) to a 16Ω load while achieving better than -98dB of THD+N , more than 108dB of SNR, and about 108dB PSRR while still maintaining a peak power efficiency of more than 84%

Radio over fiber broadband access networks architectures based on wavelength division multiplexing techniques

The recent remarkable growth in bandwidth of both wired optical and wireless access networks supports a burst of new high bandwidth Internet applications such as: peer-topeer file sharing, cloud storage, on-line gaming, video streaming, etc. Within this scenario, the convergence of fixed and wireless access networks offers significant opportunities for network operators to satisfy user demands, and simultaneously reduce the cost of implementing and running separated wireless and wired networks. The integration of wired and wireless network can be accomplished within several scenarios and at several levels. In this thesis we will focus on converged radio over fiber architectures, particularly on two application scenarios: converged optical 60 GHz wireless networks and wireless overlay backhauling over bidirectional colorless wavelength division multiplexing passive optical networks (WDM-PONs). In the first application scenario, optical 60 GHz signal generation using external modulation of an optical carrier by means of lithium niobate (LiNbO3) Mach- Zehnder modulators (MZM) is considered. The performance of different optical modulation techniques, robust against fiber dispersion is assessed and dispersion mitigation strategies are identified. The study is extended to 60 GHz carriers digitally modulated with data and to systems employing subcarrier multiplexed (SCM) mm-wave channels. In the second application scenario, the performance of WDM-PONs employing reflective semiconductor optical amplifiers (RSOAs), transmitting an overlay orthogonal frequency-division multiplexing (OFDM) wireless signal is assessed analytically and experimentally, with the relevant system impairments being identified. It is demonstrated that the intermodulation due to the beating of the baseband signal and wireless signal at the receiver can seriously impair the wireless channel. Performance degradation of the wireless channel caused by the RSOA gain modulation owing to the downstream baseband data is also assessed, and system design guidelines are provided.Universidade do Algarve, Faculdade de Ciências e Tecnologi

Radio over fiber broadband access networks architectures based on wavelength division multiplexing techniques

The recent remarkable growth in bandwidth of both wired optical and wireless access networks supports a burst of new high bandwidth Internet applications such as: peer-topeer file sharing, cloud storage, on-line gaming, video streaming, etc. Within this scenario, the convergence of fixed and wireless access networks offers significant opportunities for network operators to satisfy user demands, and simultaneously reduce the cost of implementing and running separated wireless and wired networks. The integration of wired and wireless network can be accomplished within several scenarios and at several levels. In this thesis we will focus on converged radio over fiber architectures, particularly on two application scenarios: converged optical 60 GHz wireless networks and wireless overlay backhauling over bidirectional colorless wavelength division multiplexing passive optical networks (WDM-PONs). In the first application scenario, optical 60 GHz signal generation using external modulation of an optical carrier by means of lithium niobate (LiNbO3) Mach- Zehnder modulators (MZM) is considered. The performance of different optical modulation techniques, robust against fiber dispersion is assessed and dispersion mitigation strategies are identified. The study is extended to 60 GHz carriers digitally modulated with data and to systems employing subcarrier multiplexed (SCM) mm-wave channels. In the second application scenario, the performance of WDM-PONs employing reflective semiconductor optical amplifiers (RSOAs), transmitting an overlay orthogonal frequency-division multiplexing (OFDM) wireless signal is assessed analytically and experimentally, with the relevant system impairments being identified. It is demonstrated that the intermodulation due to the beating of the baseband signal and wireless signal at the receiver can seriously impair the wireless channel. Performance degradation of the wireless channel caused by the RSOA gain modulation owing to the downstream baseband data is also assessed, and system design guidelines are provided.Universidade do Algarve, Faculdade de Ciências e Tecnologi

Embedded computing systems design: architectural and application perspectives

Questo elaborato affronta varie problematiche legate alla progettazione e all'implementazione dei moderni sistemi embedded di computing, ponendo in rilevo, e talvolta in contrapposizione, le sfide che emergono all'avanzare della tecnologia ed i requisiti che invece emergono a livello applicativo, derivanti dalle necessità degli utenti finali e dai trend di mercato. La discussione sarà articolata tenendo conto di due punti di vista: la progettazione hardware e la loro applicazione a livello di sistema. A livello hardware saranno affrontati nel dettaglio i problemi di interconnettività on-chip. Aspetto che riguarda la parallelizzazione del calcolo, ma anche l'integrazione di funzionalità eterogenee. Sarà quindi discussa un'architettura d'interconnessione denominata Network-on-Chip (NoC). La soluzione proposta è in grado di supportare funzionalità avanzate di networking direttamente in hardware, consentendo tuttavia di raggiungere sempre un compromesso ottimale tra prestazioni in termini di traffico e requisiti di implementazioni a seconda dell'applicazione specifica. Nella discussione di questa tematica, verrà posto l'accento sul problema della configurabilità dei blocchi che compongono una NoC. Quello della configurabilità, è un problema sempre più sentito nella progettazione dei sistemi complessi, nei quali si cerca di sviluppare delle funzionalità, anche molto evolute, ma che siano semplicemente riutilizzabili. A tale scopo sarà introdotta una nuova metodologia, denominata Metacoding che consiste nell'astrarre i problemi di configurabilità attraverso linguaggi di programmazione di alto livello. Sulla base del metacoding verrà anche proposto un flusso di design automatico in grado di semplificare la progettazione e la configurazione di una NoC da parte del designer di rete. Come anticipato, la discussione si sposterà poi a livello di sistema, per affrontare la progettazione di tali sistemi dal punto di vista applicativo, focalizzando l'attenzione in particolare sulle applicazioni di monitoraggio remoto. A tal riguardo saranno studiati nel dettaglio tutti gli aspetti che riguardano la progettazione di un sistema per il monitoraggio di pazienti affetti da scompenso cardiaco cronico. Si partirà dalla definizione dei requisiti, che, come spesso accade a questo livello, derivano principalmente dai bisogni dell'utente finale, nel nostro caso medici e pazienti. Verranno discusse le problematiche di acquisizione, elaborazione e gestione delle misure. Il sistema proposto introduce vari aspetti innovativi tra i quali il concetto di protocollo operativo e l'elevata interoperabilità offerta. In ultima analisi, verranno riportati i risultati relativi alla sperimentazione del sistema implementato. Infine, il tema del monitoraggio remoto sarà concluso con lo studio delle reti di distribuzione elettrica intelligenti: le Smart Grid, cercando di fare uno studio dello stato dell'arte del settore, proponendo un'architettura di Home Area Network (HAN) e suggerendone una possibile implementazione attraverso Commercial Off the Shelf (COTS)

Optimisation énergétique de processus de traitement du signal et ses applications au décodage vidéo

Consumer electronics offer today more and more features (video, audio, GPS, Internet) and connectivity means (multi-radio systems with WiFi, Bluetooth, UMTS, HSPA, LTE-advanced ... ). The power demand of these devices is growing for the digital part especially for the processing chip. To support this ever increasing computing demand, processor architectures have evolved with multicore processors, graphics processors (GPU) and ether dedicated hardware accelerators. However, the evolution of battery technology is itself slower. Therefore, the autonomy of embedded systems is now under a great pressure. Among the new functionalities supported by mobile devices, video services take a prominent place. lndeed, recent analyzes show that they will represent 70% of mobile Internet traffic by 2016. Accompanying this growth, new technologies are emerging for new services and applications. Among them HEVC (High Efficiency Video Coding) can double the data compression while maintaining a subjective quality equivalent to its predecessor, the H.264 standard. ln a digital circuit, the total power consumption is made of static power and dynamic power. Most of modern hardware architectures implement means to control the power consumption of the system. Dynamic Voltage and Frequency Scaling (DVFS) mainly reduces the dynamic power of the circuit. This technique aims to adapt the power of the processor (and therefore its consumption) to the actual load needed by the application. To control the static power, Dynamic Power Management (DPM or sleep modes) aims to stop the voltage supplies associated with specific areas of the chip. ln this thesis, we first present a model of the energy consumed by the circuit integrating DPM and DVFS modes. This model is generalized to multi-core integrated circuits and to a rapid prototyping tool. Thus, the optimal operating point of a circuit, i.e. the operating frequency and the number of active cores, is identified. Secondly, the HEVC application is integrated to a multicore architecture coupled with a sophisticated DVFS mechanism. We show that this application can be implemented efficiently on general purpose processors (GPP) while minimizing the power consumption. Finally, and to get further energy gain, we propose a modified HEVC decoder that is capable to tune its energy gains together with a decoding quality trade-off.Aujourd'hui, les appareils électroniques offrent de plus en plus de fonctionnalités (vidéo, audio, GPS, internet) et des connectivités variées (multi-systèmes de radio avec WiFi, Bluetooth, UMTS, HSPA, LTE-advanced ... ). La demande en puissance de ces appareils est donc grandissante pour la partie numérique et notamment le processeur de calcul. Pour répondre à ce besoin sans cesse croissant de nouvelles fonctionnalités et donc de puissance de calcul, les architectures des processeurs ont beaucoup évolué : processeurs multi-coeurs, processeurs graphiques (GPU) et autres accélérateurs matériels dédiés. Cependant, alors que de nouvelles architectures matérielles peinent à répondre aux exigences de performance, l'évolution de la technologie des batteries est quant à elle encore plus lente. En conséquence, l'autonomie des systèmes embarqués est aujourd'hui sous pression. Parmi les nouveaux services supportés par les terminaux mobiles, la vidéo prend une place prépondérante. En effet, des analyses récentes de tendance montrent qu'elle représentera 70 % du trafic internet mobile dès 2016. Accompagnant cette croissance, de nouvelles technologies émergent permettant de nouveaux services et applications. Parmi elles, HEVC (High Efficiency Video Coding) permet de doubler la compression de données tout en garantissant une qualité subjective équivalente à son prédécesseur, la norme H.264. Dans un circuit numérique, la consommation provient de deux éléments: la puissance statique et la puissance dynamique. La plupart des architectures matérielles récentes mettent en oeuvre des procédés permettant de contrôler la puissance du système. Le changement dynamique du couple tension/fréquence appelé Dynamic Voltage and Frequency Scaling (DVFS) agit principalement sur la puissance dynamique du circuit. Cette technique permet d'adapter la puissance du processeur (et donc sa consommation) à la charge réelle nécessaire pour une application. Pour contrôler la puissance statique, le Dynamic Power Management (DPM, ou modes de veille) consistant à arrêter les alimentations associées à des zones spécifiques de la puce. Dans cette thèse, nous présentons d'abord une modélisation de l'énergie consommée par le circuit intégrant les modes DVFS et DPM. Cette modélisation est généralisée au circuit multi-coeurs et intégrée à un outil de prototypage rapide. Ainsi le point de fonctionnement optimal d'un circuit, la fréquence de fonctionnement et le nombre de coeurs actifs, est identifié. Dans un second temps, l'application HEVC est intégrée à une architecture multi-coeurs avec une adaptation dynamique de la fréquence de développement. Nous montrons que cette application peut être implémentée efficacement sur des processeurs généralistes (GPP) tout en minimisant la puissance consommée. Enfin, et pour aller plus loin dans les gains en énergie, nous proposons une modification du décodeur HEVC qui permet à un décodeur de baisser encore plus sa consommation en fonction du budget énergétique disponible localement

Embedded System Design

A unique feature of this open access textbook is to provide a comprehensive introduction to the fundamental knowledge in embedded systems, with applications in cyber-physical systems and the Internet of things. It starts with an introduction to the field and a survey of specification models and languages for embedded and cyber-physical systems. It provides a brief overview of hardware devices used for such systems and presents the essentials of system software for embedded systems, including real-time operating systems. The author also discusses evaluation and validation techniques for embedded systems and provides an overview of techniques for mapping applications to execution platforms, including multi-core platforms. Embedded systems have to operate under tight constraints and, hence, the book also contains a selected set of optimization techniques, including software optimization techniques. The book closes with a brief survey on testing. This fourth edition has been updated and revised to reflect new trends and technologies, such as the importance of cyber-physical systems (CPS) and the Internet of things (IoT), the evolution of single-core processors to multi-core processors, and the increased importance of energy efficiency and thermal issues

Intelligent Circuits and Systems

ICICS-2020 is the third conference initiated by the School of Electronics and Electrical Engineering at Lovely Professional University that explored recent innovations of researchers working for the development of smart and green technologies in the fields of Energy, Electronics, Communications, Computers, and Control. ICICS provides innovators to identify new opportunities for the social and economic benefits of society.　 This conference bridges the gap between academics and R&D institutions, social visionaries, and experts from all strata of society to present their ongoing research activities and foster research relations between them. It provides opportunities for the exchange of new ideas, applications, and experiences in the field of smart technologies and finding global partners for future collaboration. The ICICS-2020 was conducted in two broad categories, Intelligent Circuits & Intelligent Systems and Emerging Technologies in Electrical Engineering

Advanced Trends in Wireless Communications

Physical limitations on wireless communication channels impose huge challenges to reliable communication. Bandwidth limitations, propagation loss, noise and interference make the wireless channel a narrow pipe that does not readily accommodate rapid flow of data. Thus, researches aim to design systems that are suitable to operate in such channels, in order to have high performance quality of service. Also, the mobility of the communication systems requires further investigations to reduce the complexity and the power consumption of the receiver. This book aims to provide highlights of the current research in the field of wireless communications. The subjects discussed are very valuable to communication researchers rather than researchers in the wireless related areas. The book chapters cover a wide range of wireless communication topics

5G innovation opportunities-- A discussion paper

On the shaping of 5G technologies and networks, scope for wider service and applications innovation and UK strengths and opportunities