EPIC - Energy Processing and Integrated Circuits
Total activity: 944
Type
Research group
Type of group
UPC research group
Acronym
EPIC
blanc
http://www-eel.upc.es/~adm710/WEB_DEPARTAMENT_PAG_PRINCIPAL/angles/pagina_principal/marc_recerca_ang.html Open in new window
Objectives
- Modelling, design (voltage and current modes), implementation and characterisation of analogue integrated circuits such as amplifiers, oscillators, automatically-tuned filters, communication circuits, etc.
- Modelling, design, control (linear control, current-mode control, sliding-mode control and fuzzy control), implementation and characterisation of switching power converters. Application to DC-DC and DC-AC conversions and to the series-parallel connection of converters.
- Fuzzy modelling of nonlinear dynamic systems.
- Microelectronic design of neuro-fuzzy processors and switching power converter controllers.
Keywords
convertidors de potencia conmutats,disseny VLSI,Disseny VLSI analògic en mode de corrent,modelat no lineal i control,processat fuzzy.,sintonia on-chip

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1 to 50 of 944 results
  • Observation of chaotic behavior in automatic tuning loops for continuous-time filters

     Martínez García, Herminio; Cosp Vilella, Jordi; Manzanares Brotons, Manuel
    IEEE International Midwest Symposium on Circuits and Systems
    Presentation's date: 2014-08
    Presentation of work at congresses

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    he appropriate linear dynamic modeling of continuous-time filters (CTFs) with automatic tuning loops should be obtained to assure stability in case an improved design of the loop controllers is to be carried out. With this aim, starting from a general and systematic analysis in order to obtain an equivalent small-signal linearized incremental model, from which transfer functions between output variables and control voltages are derived, the subsequent design of compensated loops with enhanced stability and dynamic performance is required. This systematic procedure allows obtaining improved controllers for the two involved control loops. However, CTFs with automatic tuning loops are nonlinear feedback systems with potential instability. What is more, nonlinear phenomena, which cannot be predicted by a design-oriented small signal modeling approach, are observed in this kind of tuning systems. The purpose of this work is to highlight that when control parameters are varied, the system could present different kinds of dynamical nonlinear phenomena such as bifurcations and chaotic behavior, which cannot be predicted by the small signal design-oriented model.

  • Global MPPT scheme for photovoltaic string inverters based on restricted voltage window search algorithm

     Boztepe, Mutlu; Guinjoan Gispert, Francisco; Velasco Quesada, Guillermo; Silvestre Berges, Santiago; Chouder, Aissa; Karatepe, Engin
    IEEE transactions on industrial electronics
    Date of publication: 2014-07-01
    Journal article

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    String inverter photovoltaic (PV) systems with bypass diodes require improved global maximum power point tracking (GMPPT) algorithms to effectively reach the absolute maximum power operating point. Several GMPPT algorithms have been proposed to deal with this problem, but most of them require scanning wide voltage ranges of the PV array from nearly zero voltage to open-circuit voltage that increases the scanning time and, in turn, causes energy loss. This paper presents a novel GMPPT method which significantly restricts the voltage window search range and tracks the global power peak rapidly in all shading conditions. Simulation tests and experimental comparisons with another GMPPT algorithm are presented to highlight the features of the presented approach.

  • On the Scalability Limits of Communication Networks to the Nanoscale

     Llatser Marti, Ignacio
    Defense's date: 2014-01-17
    Universitat Politècnica de Catalunya
    Theses

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    Los nanosistemas, sistemas integrados con un tamaño total de unos pocos micrómetros, son capaces de interactuar en la nanoescala, pero su corto radio de acción limita su utilidad en escenarios prácticos. Las nanoredes, que surgen de la interconexión de nanosistemas, amplían su ámbito de operación permitiendo la comunicación entre nanosistemas, aumentando de esta forma sus aplicaciones potenciales. Con el fin de dotar de capacidades de comunicación a los nanosistemas, su subsistema de comunicación debe reducirse a unos pocos micrómetros. Existen dudas sobre la viabilidad de miniaturizar las antenas metálicas actuales a un tamaño tan pequeño, especialmente porque su frecuencia de resonancia sería extremadamente alta (en el espectro óptico), lo que causaría a una gran atenuación de las ondas radiadas. Como alternativa, se han propuesto dos nuevos paradigmas para implementar comunicaciones inalámbricas entre nanosistemas: las comunicaciones moleculares y las comunicaciones inalámbricas basadas en grafeno. Por un lado, las comunicaciones moleculares consisten en el intercambio de moléculas entre nanosistemas, inspirado en la comunicación entre células vivas. En las comunicaciones moleculares basadas en difusión (DMC), las moléculas emitidas se propagan por el medio mediante un proceso de difusión hasta que alcanzan el receptor. Por otro lado, el grafeno (una lámina de átomos de carbono de un átomo de espesor) permite implementar antenas de grafeno plasmónicas, o grafenas. Debido a efectos plasmónicos, grafenas con un tamaño de unos pocos micrómetros radian ondas en la banda de terahercios, dando lugar al paradigma de las comunicaciones inalámbricas basadas en grafeno (GWC). Para averiguar cómo escalan las redes de comunicación a medida que se reducen sus dimensiones, esta tesis se presenta un análisis de la escalabilidad de las redes de comunicaciones hacia la nanoescala, siguiendo un modelo general con la menor cantidad posible de hipótesis. Hemos propuesto dos esquemas de detección en DMC: detección de amplitud y detección de energía. Hemos identificado importantes métricas de rendimiento y calculado su escalabilidad con respecto a la distancia de transmisión, que difiere significativamente respecto a las comunicaciones inalámbricas tradicionales. Estas nuevas tendencias de escala requieren el diseño de nuevos protocolos de red especialmente adaptados a las redes de DMC. El análisis de la propagación de ondas plasmónicas en grafenas permite determinar sus propiedades de radiación. En particular, la frecuencia de resonancia de las grafenas no sólo es más baja que en antenas metálicas, sino que también aumenta más lentamente a medida que reducimos su longitud. Por otra parte, la frecuencia de resonancia de las grafenas puede ser ampliamente controlada en función de parámetros como las dimensiones de la grafena, el tiempo de relajación del grafeno y el potencial químico. Además, proponemos un montaje experimental que permite la medición de grafenas alimentadas con una fuente fotoconductora. También hemos analizado los efectos de la absorción molecular en el canal de terahercios a corto alcance, el escenario de operación de las grafenas. La absorción molecular es un proceso por el cual moléculas presentes en la atmósfera absorben parte de la energía de las ondas radiadas por las grafenas, degradando su rendimiento. Hemos cuantificado esta degradación derivando parámetros de rendimiento en este escenario, que muestran novedosas tendencias de escalabilidad en función de la distancia de transmisión. Por último, hemos encontrado que la capacidad de canal de GWC escala mejor a medida que el tamaño de la antena se reduce con respecto a las comunicaciones inalámbricas tradicionales. En consecuencia, las GWC requerirán una potencia de transmisión más baja para lograr un cierto rendimiento. Estos resultados establecen un marco general que puede servir de guía para diseñar las futuras redes de comunicaciones inalámbricas entre nanosistemas.

  • Energy-balance control of PV cascaded multilevel grid-connected inverters for phase-shifted and level-shifted pulse-width modulations

     Chavarria Roe, Javier; Biel Sole, Domingo; Guinjoan Gispert, Francisco; Meza Benavides, Carlos; Negroni Vera, Juan José
    IEEE transactions on industrial electronics
    Date of publication: 2013-01
    Journal article

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    This paper presents an energy-balance control strategy for a cascaded single-phase grid-connected H-bridge multilevel inverter linking n independent photovoltaic (PV) arrays to the grid. The control scheme is based on an energy-sampled data model of the PV system and enables the design of a voltage loop linear discrete controller for each array, ensuring the stability of the system for the whole range of PV array operating conditions. The control design is adapted to phase-shifted and level-shifted carrier pulsewidth modulations to share the control action among the cascade-connected bridges in order to concurrently synthesize a multilevel waveform and to keep each of the PV arrays at its maximum power operating point. Experimental results carried out on a seven-level inverter are included to validate the proposed approach.

    This paper presents an energy-balance control strategy for a cascaded single-phase grid-connected H-bridge multilevel inverter linking n independent PV arrays to the grid. The control scheme is based on an energy-sampled data model of the PV system and enables the design of a voltage loop linear discrete controller for each array ensuring the stability of the system for the whole range of PV arrays operating conditions. The control design is adapted to Phase-Shifted and Level-Shifted Carrier PWM to share the control action among the cascadeconnected bridges in order to concurrently synthesize a multilevel waveform and to keep each of the PV arrays at its maximum power operating point. Experimental results carried out on a 7-level inverter are included to validate the proposed approach.

  • A study on multi-level PWM and asynchronous Sigma Delta modulations for enhanced bandlimited signal tracking in switching power amplifiers

     Garcia Tormo, Albert; Poveda Lopez, Alberto; Alarcon Gallo, Eduardo; Guinjoan Gispert, Francisco
    IEEE transactions on circuits and systems I: regular papers
    Date of publication: 2013-06
    Journal article

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    This work deals with multi-level switching amplifiers, in the context of high-efficiency power amplification for signal tracking applications. In particular, this paper evaluates the reduction in the error signal's power due to multi-level power amplification (compared to conventional two-level amplifiers) and compares the performance of two multi-level pulse modulations: PWM and Asynchronous Modulation. First the intrinsic bandwidth limits of multi-level switching amplifiers are inferred, to clearly state the advantages and limitations of multi-level power amplification. From the existing analyses of Pulse Width Modulation already reported in the literature, PWM is herein extended to multiple levels based on an equivalent representation, which allows to derive a closed expression for the power spectrum of multi-level PWM in bandlimited signal tracking. The Asynchronous Modulation is extended to multiple levels and the resulting multi-level encoding algorithm is analyzed in both time and frequency domains. The performance of both modulations is characterized and compared at different operating frequencies and using different number of levels. The main outcomes of this in-depth characterization show that, if the switching frequency is high enough, the tracking error is independent of the modulation and the switching frequency, i.e., it only depends upon the number of levels, which points out the suitability of asynchronous modulations for relatively low switching frequencies (compared to the number of levels).

    This work deals with multi-level switching amplifiers, in the context of high-efficiency power amplification for signal tracking applications. In particular, this paper evaluates the reduction in the error signal's power due to multi-level power amplification (compared to conventional two-level amplifiers) and compares the performance of two multi-level pulse modulations: PWM and Asynchronous ${{Sigma}} {{Delta}}$ Modulation. First the intrinsic bandwidth limits of multi-level switching amplifiers are inferred, to clearly state the advantages and limitations of multi-level power amplification. From the existing analyses of Pulse Width Modulation already reported in the literature, PWM is herein extended to multiple levels based on an equivalent representation, which allows to derive a closed expression for the power spectrum of multi-level PWM in bandlimited signal tracking. The Asynchronous ${{Sigma}} {{Delta}}$ Modulation is extended to multiple levels and the resulting multi-level encoding algorithm is analyzed in both time and frequency domains. The performance of both modulations is characterized and compared at different operating frequencies and using different number of levels. The main outcomes of this in-depth characterization show that, if the switching frequency is high enough, the tracking error is independent of the modulation and the switching frequency, i.e., it only depends upon the number of levels, which points out the suitability of asynchronous modulations for relatively low switching frequencies (compared to the number of levels).

  • La sostenibilidad en los proyectos de ingeniería

     Garcia Almiñana, Jordi; García Gómez, Helena; Lopez Alvarez, David; Sanchez Carracedo, Fermin; Vidal Lopez, Eva Maria; Alier Forment, Marc; Cabre Garcia, Jose Maria
    ReVisión
    Date of publication: 2013-09
    Journal article

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    El Trabajo de Fin de Grado representa la última prueba para que el estudiante de grado demuestre que está preparado para ejercer como ingeniero, elaborando y defendiendo un proyecto de envergadura. El proyecto debe cumplir todos los requisitos que se exigen a un proyecto de ingeniería, desde el análisis del problema hasta la presentación de una solución. Los autores del presente trabajo pensamos que todo proyecto de ingeniería debe incorporar un informe de sostenibilidad que demuestre que el proyecto es sostenible en los ámbitos social, ambiental y económico. Existe poca experiencia en este tema, tanto en la empresa como en la universidad, ya que las empresas (algunas) hace pocos años que han incorporado la sostenibilidad como uno de los criterios de realización de sus proyectos y las universidades apenas han comenzado a trabajar en esa dirección. En este trabajo se presentan algunas reflexiones sobre cómo debería ser tratada la sostenibilidad en un proyecto de ingeniería, y en particular cómo se pueden aplicar estas ideas al Trabajo de Fin de Grado.

  • Technologies for electric current sensors

     Velasco Quesada, Guillermo; Conesa Roca, Alfons; Roman Lumbreras, Manuel
    Date of publication: 2013-05-22
    Book chapter

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  • Technologies for electric current sensors

     Velasco Quesada, Guillermo; Conesa Roca, Alfons; Roman Lumbreras, Manuel
    Date of publication: 2013-08-01
    Book chapter

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    Within the field of study of classical physics, we can find the branch concerned with electromagnetic phenomena: electromagnetism. Electromagnetism describes the interaction between electric charges through the concepts of electric and magnetic fields. The formulation of the electromagnetic theory principles has enabled the engineering sciences, such as electricity and electronics, to develop applications related to the treatment of energy and information using electric charges as physical support. Most operations performed on the processing of energy or information supported by electric charges involve the movement of these charges, and there are two basic electric magnitudes to represent this movement: electric voltage (also called potential difference or voltage) and electric current. Regardless the scope of the developed application, many electric or electronic systems need to measure the value of either of these two magnitudes. This chapter is devoted to reviewing the various techniques currently available to measure or sensing the electric current intensity.

  • Area and laser power scalability analysis in photonic networks-on-chip

     Abadal Cavalle, Sergi; Cabellos Aparicio, Alberto; Lazaro Villa, Jose Antonio; Nemirovsky, Mario; Alarcon Cot, Eduardo Jose; Sole Pareta, Josep
    International Conference on Optical Network Design and Modeling
    Presentation's date: 2013-04-18
    Presentation of work at congresses

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    In the last decade, the field of microprocessor architecture has seen the rise of multicore processors, which consist of the interconnection of a set of independent processing units or cores in the same chip. As the number of cores per multiprocessor increases, the bandwidth and energy requirements for their interconnection networks grow exponentially and it is expected that conventional on-chip wires will not be able to meet such demands. Alternatively, nanophotonics has been regarded as a strong candidate for chip communication since it could provide high bandwidth with low area and energy footprints. However, issues such as the unavailability of efficient on-chip light sources or the difficulty of implementing all-optical buffering or header processing hinder the development of scalable photonic on-chip networks. In this paper, the area and laser power of several photonic on-chip network proposals is analytically modeled and its scalability is evaluated. Also, a graphene-based hybrid approach is presented

    In the last decade, the field of microprocessor architecture has seen the rise of multicore processors, which consist of the interconnection of a set of independent processing units or cores in the same chip. As the number of cores per multiprocessor increases, the bandwidth and energy requirements for their interconnection networks grow exponentially and it is expected that conventional on-chip wires will not be able to meet such demands. Alternatively, nanophotonics has been regarded as a strong candidate for chip communication since it could provide high bandwidth with low area and energy footprints. However, issues such as the unavailability of efficient on-chip light sources or the difficulty of implementing all-optical buffering or header processing hinder the development of scalable photonic on-chip networks. In this paper, the area and laser power of several photonic on-chip network proposals is analytically modeled and its scalability is evaluated. Also, a graphene-based hybrid wireless/optical-wired approach is presented, aiming at enabling end-to-end photonic on-chip networks to scale beyond thousands of cores

  • La gestión de la calidad: algunas reflexiones sobre los procesos de calidad que se implantan en los centros docentes universitarios

     Perez Gracia, Maria de La Vega; Lopez Lopez, Jose; Buenestado Caballero, Pablo; Garcia-Alzórriz Pardo, Juan Antonio; Torres Camara, Ricardo; Martinez Sanchez, Joan; Velasco Quesada, Guillermo
    Congreso Universitario de Innovación Educativa en las Enseñanzas Técnicas (CUIEET)
    Presentation's date: 2013-07-12
    Presentation of work at congresses

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    Resumen. Tras diseñar un sistema interno de garantía de calidad se inició el proceso de implantación. Sin embargo, este proceso se ha dilatado en el tiempo y no se ha podido finalizar todavía. Es posible que muchos de los problemas con los que nos hemos encontrado sean fallos del sistema diseñado, que no fueron previstos por el centro ni detectados por los revisores externos. La discusión sobre nuestra experiencia, contrastándola con la de otros centros puede ser una herramienta valiosa para mejorar un sistema complejo. Abstract. After the quality system design, implementation was the second step. However, several difficulties caused the delay in the implementation process and the system is not yet finalized. It is possible that some of the problems in the process were due to a non appropriate design or evaluation of the quality system. In our opinion, the discussion about the experience, contrasted to the other centres¿ experiences could help in the improvement of the system.

  • Supply modulator for linear wideband RF power amplifiers

     Turkson, Richard; Silva-Martínez, José; Martínez García, Herminio
    Seminario Anual de Automática, Electrónica Industrial e Instrumentación
    Presentation's date: 2013-07-11
    Presentation of work at congresses

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    This paper deals with the design techniques of power efficient switching regulators intended for linear power amplifiers employing envelope tracking techniques in wideband wireless standards. The bottlenecks involve a tradeoff between ripple voltage, slew rate and bandwidth. The slew rate limitation is identified as the main challenge, then a `bang-bang¿ slew-enhancement technique is proposed. This approach enables the use of efficient supply modulators in wideband power amplifiers. The proposed scheme does not significantly degrade PA efficiency and preserves the stability of the switching regulator. The prototype has been implemented using the TSMC 0.18 µm technology; schematic simulation results in Cadence ® are presented to prove the concept.

  • Envelope tracking technique with bang-bang slew-rate enhancer for linear wideband RF PAs

     Turkson, Richard; Prakash, Suraj; Silva-Martínez, José; Martínez García, Herminio
    IEEE International Midwest Symposium on Circuits and Systems
    Presentation's date: 2013-08-06
    Presentation of work at congresses

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    Output-capacitorless CMOS LDO regulator based on high slew-rate current-mode transconductance amplifier  Open access

     Saberkari, Alireza; Fathipour, Rasoul; Martínez García, Herminio; Poveda Lopez, Alberto; Alarcon Cot, Eduardo Jose
    IEEE International Symposium on Circuits and Systems
    Presentation's date: 2013-05-21
    Presentation of work at congresses

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    A low quiescent current output-capacitorless CMOS LDO regulator based on a high slew-rate current-mode transconductance amplifier (CTA) as an error amplifier is presented. Load transient characteristic of the proposed LDO is improved even at low quiescent currents, by using a local common-mode feedback (LCMFB) in the proposed CTA. This provides an increase in the order of transfer characteristic of the circuit, thereby enhancing the slew-rate at the gate of pass transistor. The proposed CTA-based LDO topology has been designed and post-layout simulated in HSPICE, in a 0.18 µm CMOS process to supply a load current between 0-100 mA. Postlayout simulation results reveal that the proposed LDO is stable without any internal compensation strategy and with on-chip output capacitor or lumped parasitic capacitances at the output node between 10-100 pF.

    A low quiescent current output-capacitorless CMOS LDO regulator based on a high slew-rate current-mode transconductance amplifier (CTA) as an error amplifier is presented. Load transient characteristic of the proposed LDO is improved even at low quiescent currents, by using a local common-mode feedback (LCMFB) in the proposed CTA. This provides an increase in the order of transfer characteristic of the circuit, thereby enhancing the slew-rate at the gate of pass transistor. The proposed CTA-based LDO topology has been designed and post-layout simulated in HSPICE, in a 0.18 μm CMOS process to supply a load current between 0-100 mA. Postlayout simulation results reveal that the proposed LDO is stable without any internal compensation strategy and with on-chip output capacitor or lumped parasitic capacitances at the output node between 10-100 pF.

  • Maximizing efficiency through impedance matching from a circuit-centric model of non-radiative resonant wireless power transfer

     Bou Balust, Elisenda; Sedwick, Raymond; Alarcon Cot, Eduardo Jose
    IEEE International Symposium on Circuits and Systems
    Presentation's date: 2013-05-21
    Presentation of work at congresses

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    Recent research in wireless power transfer (WPT) using resonant inductive coupling has demonstrated very high efficiencies (above 40%) at large distances compared to the transmitting element dimensions, thereby exponentially increasing the number of potential applications of WPT. Since resonant inductive coupling is a very multidisciplinary field, different approaches have been proposed to predict the behaviour of these systems from the physical theory of resonators (coupled-mode theory), reflected load theory and circuit theory. Also, there is in this field a heterogeneous definition of metrics without a clear optimization process. In this article we unify the different metrics and demonstrate how to maximize the power transfer efficiency in a non-radiative resonant wireless power transfer link from a circuit-centric point of view providing design guidelines in terms of optimal load impedance, optimal source impedance and optimal distance between coils.

  • Magnetic characterization of interfering objects in resonant inductive coupling wireless power transfer

     Bou Balust, Elisenda; Vidal, D.; Sedwick, Raymond; Alarcon Cot, Eduardo Jose
    Progress in Electromagnetics Research Symposium
    Presentation's date: 2013-08-16
    Presentation of work at congresses

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    Resonant Inductive Coupling (RIC) Wireless Power Transfer is a key technology to provide an efficient and harmless wireless energy channel to consumer electronics, biomedical implants and wireless sensor networks. However, there are two factors that are limiting the applicability of this technology: the effects of distance variation between transmitter and receiver and the effects of interfering objects. While distance variation in WPT has been thoroughly studied, the effects of conductive interfering objects in resonant inductive coupling links are still unclear. When a conductive element is in the vicinity of a RIC link, both the transmitter and the receiver can experiment a change on their resonant frequencies as well as their impedances. This can greatly affect the effciency of such WPT link causing it to a) make the transmitter and/or receiver act as a pass-band filter and b) loose part of the transmitter magnetic field through coupling to the interfering object. Depending on the natural resonant frequency of the object and the distances between this object and the transmitter and receiver antennas, this can affect significantly the RIC wireless power transfer link. In this article, we characterize the Magnetic behavior of a resonant inductive coupled link in the presence of a conductive interfering object using a Finite Element Field Solver (FEKO). Several distances between interference and transmitter/receiver are analyzed providing a design space exploration and applicability study of this link.

  • Chaotic behaviour in on-chip automatic tuning loops for continuous-time filters

     Martínez García, Herminio; El Aroudi, Abdelali; Alarcon Cot, Eduardo Jose; Poveda Lopez, Alberto
    Seminario Anual de Automática, Electrónica Industrial e Instrumentación
    Presentation's date: 2013-07-11
    Presentation of work at congresses

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    Continuous-time filters (CTF) with automatic tuning loops are nonlinear feedback systems with potential instability. While an appropriate small signal linear dynamic modeling of the tunable filter should be obtained for design purpose, its ability to predict the real nonlinear dynamic behavior of the system is limited. In order to overcome this problem, a general and systematic procedure is used to obtain a large signal nonlinear model. The obtained model can accurately predict nonlinear phenomena such as bifurcations and chaotic behavior. From this model, some numerical simulations results are presented in this paper. As far as the authors know, the observation of these phenomena in CTF with tuning loops has not been previously presented. Thus, the results obtained in this work can provide some help to obtain improved controllers (with higher bandwidth and better performance) for the two involved control loops.

  • La sostenibilidad en los proyectos de ingeniería

     Cabre Garcia, Jose Maria; Garcia Almiñana, Jordi; García Gómez, Helena; Lopez Alvarez, David; Sanchez Carracedo, Fermin; Vidal Lopez, Eva Maria; Alier Forment, Marc
    Jornadas de Enseñanza Universitaria de la Informática
    Presentation's date: 2013-07-12
    Presentation of work at congresses

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    El Trabajo de Fin de Grado representa la última prueba para que el estudiante de grado demuestre que está preparado para ejercer como ingeniero, elaborando y defendiendo un proyecto de envergadura. El proyecto debe cumplir todos los requisitos que se exigen a un proyecto de ingeniería, desde el análisis del problema hasta la presentación de una solución. Los autores del presente trabajo pensamos que todo proyecto de ingeniería debe incorporar un informe de sostenibilidad que demuestre que el proyecto es sostenible en los ámbitos social, ambiental y económico. Existe poca experiencia en este tema, tanto en la empresa como en la universidad, ya que las empresas (algunas) hace pocos años que han incorporado la sostenibilidad como uno de los criterios de realización de sus proyectos y las universidades apenas han comenzado a trabajar en esa dirección. En este trabajo se presentan algunas reflexiones sobre cómo debería ser tratada la sostenibilidad en un proyecto de ingeniería, y en particular cómo se pueden aplicar estas ideas al Trabajo de Fin de Grado.

  • Interference analysis on resonant inductive coupled wireless power transfer

     Bou Balust, Elisenda; Alarcon Cot, Eduardo Jose; Sedwick, Raymond; Fisher, Peter
    IEEE International Symposium on Circuits and Systems
    Presentation's date: 2013-05-22
    Presentation of work at congresses

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    Resonant Inductive Coupling Wireless Power Transfer is a key technology to provide an efficient and harmless wireless energy channel to consumer electronics, biomedical implants and wireless sensor networks. However, there are two factors that are limiting the applicability of this technology: the effects of distance variation between transmitter and receiver and the effects of interfering objects. While distance variation in WPT has been thoroughly studied, the effects of interfering objects in resonant inductive coupling links are still unclear. In this article we propose a new circuit-based analytical model that predicts the behavior of a resonant inductive coupled link in the presence of interfering objects and verify the obtained results with a Finite Element Field Solver.

    Resonant Inductive Coupling Wireless Power Transfer is a key technology to provide an efficient and harmless wireless energy channel to consumer electronics, biomedical implants and wireless sensor networks. However, there are two factors that are limiting the applicability of this technology: the effects of distance variation between transmitter and receiver and the effects of interfering objects. While distance variation in WPT has been thoroughly studied, the effects of interfering objects in resonant inductive coupling links are still unclear. In this article we propose a new circuit-based analytical model that predicts the behavior of a resonant inductive coupled link in the presence of interfering objects and verify the obtained results with a Finite Element Field Solver.

  • Access to the full text
    Designing CDIO capstone projects: a systems thinking approach  Open access

     Alarcon Cot, Eduardo Jose; Bou Balust, Elisenda; Camps Carmona, Adriano Jose; Bragos Bardia, Ramon; Oliveras Verges, Albert; Pegueroles Valles, Josep Rafel; Sayrol Clols, Elisa; Marques Acosta, Fernando
    International CDIO Conference
    Presentation's date: 2013-06-10
    Presentation of work at congresses

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    Given the all-pervasiveness of Systems thinking -which consists of thinking about things as systems- as a way of reasoning, in this work we will describe its application to make an interpretation of how to conceive and design a final year CDIO capstone course. Both the student teamwork structure as well as the complex engineering system itself addressed in the project are described in terms of entities, links, form and function, thereby pointing out their formal and functional interaction. The ultimate goal of the Systems thinking perspective is, given the necessary ingredients, to try maximizing the chances of the emergence of a fruitful capstone course, namely a culminating project that yields a set of students qualified to CDIO complex engineering systems.

    Given the all-pervasiveness of Systems thinking -which consists of thinking about things as systemsas a way of reasoning, in this work we will describe its application to make an interpretation of how to conceive and design a final year CDIO capstone course. Both the student teamwork structure as well as the complex engineering system itself addressed in the project are described in terms of entities, links, form and function, thereby pointing out their formal and functional interaction. The ultimate goal of the Systems thinking perspective is, given the necessary ingredients, to try maximizing the chances of the emergence of a fruitful capstone course, namely a culminating project that yields a set of students qualified to CDIO complex engineering systems.

  • Power gyrator structures and their use as cells for energy processing in photovoltaic solar facilities

     Martínez García, Herminio; Grau Saldes, Antoni; Bolea Monte, Yolanda; Gamiz Caro, Juan
    Spanish-Portuguese Conference on Electrical Engineering
    Presentation's date: 2013-07-04
    Presentation of work at congresses

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    This paper provides a classification of high efficiency switching power-gyrator structures and their use as cells for energy processing in photovoltaic solar facilities. Having into account the properties of these topologies presented in the article, their inclusion in solar facilities allows increasing the performance of the whole installation. Thus, the design, simulation and implementation of a G-type power gyrator are carried out throughout the text. In addition, in order to obtain the maximum power from the photovoltaic solar panel, a maximum power point tracking (MPPT) is mandatory in the energy processing path. Therefore, the practical implementation carried out includes a control loop of the power gyrator in order to track the aforementioned maximum power point of the photovoltaic solar panel.

  • Observation of chaotic behavior in automatic tuning loops for continuous¿time filters

     Martínez García, Herminio; Cosp Vilella, Jordi; Manzanares Brotons, Manuel
    IEEE International Midwest Symposium on Circuits and Systems
    Presentation's date: 2013-08-06
    Presentation of work at congresses

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    The appropriate linear dynamic modeling of continuous¿time filters (CTFs) with automatic tuning loops should be obtained to assure stability in case an improved design of the loop controllers is to be carried out. With this aim, starting from a general and systematic analysis in order to obtain an equivalent small¿signal linearized incremental model, from which transfer functions between output variables and control voltages are derived, the subsequent design of compensated loops with enhanced stability and dynamic performance is required. This systematic procedure allows obtaining improved controllers for the two involved control loops. However, CTFs with automatic tuning loops are nonlinear feedback systems with potential instability. What is more, nonlinear phenomena, which cannot be predicted by a design-oriented small signal modeling approach, are observed in this kind of tuning systems. The purpose of this work is to highlight that when control parameters are varied, the system could present different kinds of dynamical nonlinear phenomena such as bifurcations and chaotic behavior, which cannot be predicted by the small signal design-oriented model.

  • The use of power gyrator structures for energy processing in photovoltaic solar facilities

     Martínez García, Herminio; Grau Saldes, Antoni; Bolea Monte, Yolanda
    IEEE International Conference on Industrial Informatics
    Presentation's date: 2013-07-30
    Presentation of work at congresses

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    This paper provides a classification of high efficiency switching power-gyrator structures and their use as cells for energy processing in photovoltaic solar facilities. Having into account the properties of these topologies presented in the article, their inclusion in solar facilities allows increasing the performance of the whole installation. Thus, the design, simulation and implementation of a G-type power gyrator are carried out throughout the text. In addition, in order to obtain the maximum power from the photovoltaic solar panel, a maximum power point tracking (MPPT) is mandatory in the energy processing path. Therefore, the practical implementation carried out includes a control loop of the power gyrator in order to track the aforementioned maximum power point of the photovoltaic solar panel.

  • Design of an on-chip linear-assisted DC-DC voltage regulator

     Cosp Vilella, Jordi; Martínez García, Herminio
    IEEE International Conference on Electronics, Circuits and Systems
    Presentation's date: 2013-12-10
    Presentation of work at congresses

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    This article shows the design of an on-chip CMOS linear-assisted DC-DC regulator. It results a good alternative topology to classic switching DC-DC power converters. In the presented technique, an auxiliary linear regulator is used to cancel the output voltage ripple and provides fast responses for load and line variations. On the other hand, a switching converter, connected in parallel, allows supplying almost the whole output current demanded by the load. The objective of this linear-assisted regulator or hybrid topology is to achieve a high efficiency of switching converters, with suitable load and line regulation features, typical of linear regulators. In this kind of on-chip applications, CMOS is the current prevailing technology. Thus, in order to implement on-chip power supply systems and on-chip power management systems with low-to-medium current consumption, this structure has good features.

  • Inductively coupled wireless power transfer with Class-E2 DC-DC converter

     Nagashima, Tomoharu; Inoue, Kazuhide; Wei, Xiuqin; Bou, Elisenda; Alarcon Cot, Eduardo Jose; Sekiya, Hiroo
    European Conference on Circuit Theory and Design
    Presentation's date: 2013-09-08
    Presentation of work at congresses

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    This paper proposes an inductive coupled wireless power transfer (WPT) system with class-E2 dc-dc converter along with its design procedure. The proposed WPT system can achieve high power-conversion efficiency at high frequencies because it satisfies the class-E zero-voltage switching and zero-derivative-voltage switching conditions on both the inverter and the rectifier. By using the class-E inverter as a transmitter and the class-E rectifier as a receiver, high power-delivery efficiency can be achieved in the designed WPT system. By using a numerical design procedure proposed in the previous work, it is possible to design the WPT system without considering the impedance matching for satisfying the class-E ZVS/ZDS conditions. The experimental results of the design example showed the overall efficiency of 85:1%at 100Woutput power and 200 kHz operating frequency.

  • Design of a 4.5-V, 450-mA low-dropout voltage linear regulator based on a cascoded OTA

     Martínez García, Herminio; Grau Saldes, Antoni; Bolea Monte, Yolanda
    Annual Conference of the IEEE Industrial Electronics Society
    Presentation's date: 2013-11-13
    Presentation of work at congresses

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    This article aims to present the design of a 4.5-V 450-mA low drop-out (LDO) voltage linear regulator based on a two-stage cascoded operational transconductance amplifier (OTA) as error amplifier. The aforementioned two-stage OTA is designed with cascoded current mirroring technique to boost up the output impedance. The proposed OTA has a DC gain of 101 dB under no load condition. The designed reference voltage included in the LDO regulator is provided by a band gap reference with the temperature coefficient (T¿) of 0.025 mV/ºC. The proposed LDO regulator has a maximum drop-out voltage of 0.5 V @ 450 mA of load current, and has the worst case power supply rejection ratio (PSRR) of [54.5 dB, 34.3 dB] @ [100 Hz, 10 kHz] in full load condition. All the proposed circuits are designed using a 0.35 µm CMOS technology. The design is checked in order to corroborate its performance for wide range of input voltage, founding that the circuit design works fine meeting all the initial specification requirements.

  • UPCSAT-1, demostrador CubeSat para observación terrestre

     Jove Casulleras, Roger; Camps Carmona, Adriano Jose; Vall-llossera Ferran, Mercedes Magdalena; Bou Balust, Elisenda; Ramos Castro, Juan Jose; Alarcon Cot, Eduardo Jose; Alonso Arroyo, Alberto
    Congreso de la Asociación Española de Teledetección
    Presentation's date: 2013-10
    Presentation of work at congresses

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    UPCSat-1, es el primer proyecto de la Universitat Politécnica de Catalunya para construir y lanzar un pico- satélite. El objetivo principal de este proyecto es construir, ensamblar, testear y poner en órbita baja terrestre (LEO) un sensor óptico y un sensor de oxígeno monoatómico entre otros demostradores tecnológicos. Empezado en 2007 y actualmente en fase de integración, el satélite UPCSat-1 pretende demostrar la validez de la plataforma y las tecnologías que incorpora. Su objetivo es adquirir el know-how para la fabricación de CubeSats para preparar misiones más complejas en un futuro cercano. Por otro lado el proyecto tiene un fuerte componente educacional puesto que algunos de los subsistemas han sido desarrollados por nuestros estudiantes a través de sus proyectos finales de carrera. Se espera el lanzamiento para antes de 2015.

  • SiC Power JFET Electrothermal Macromodel

     Massana, Francisco; Chavarria Roe, Javier; Biel Sole, Domingo; Poveda Lopez, Alberto; Guinjoan Gispert, Francisco
    International Conference Mixed Design of Integrated Circuits and Systems
    Presentation's date: 2013-06-21
    Presentation of work at congresses

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  • The Machreck Energy Development - Solar project MED-Solar

     Velasco Quesada, Guillermo; Guinjoan Gispert, Francisco; Pique Lopez, Robert; Roman Lumbreras, Manuel; Vallvé, Xavier; Tarragó, J.; Bugatti, N.
    International Multi-Conference on Systems, Signals and Devices
    Presentation's date: 2013-03-19
    Presentation of work at congresses

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    The aim of this communication is to introduce the project MED-Solar, acronym of Machrek Energy Development. This project is part of the new European Neighborhood Policy (ENP), policy that seeks to reinforce relations with neighboring countries to the east and south in order to promote prosperity, stability and security at its borders. The main objective of this project is the promotion and implementation of innovative technologies and know-how transfer in the field of solar energy, including that stemming from private sector, and that may be implemented in particular or public facilities through public procurement processes.

  • On chaotic behavior in automatic tuning loops for continuous-time filters

     Cosp Vilella, Jordi; Martínez García, Herminio
    European Conference on Circuit Theory and Design
    Presentation's date: 2013-09-10
    Presentation of work at congresses

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    Continuous-time filters (CTFs) with automatic tuning loops are nonlinear feedback systems with potential instability. Thus, their appropriate linear dynamic modeling should be obtained to assure stability in case of an improved design of the loop controllers is to be carried out. A systematic approach using a small signal model would allow obtaining these controllers. However, bifurcations and nonlinear phenomena may appear which cannot be predicted by this analysis. This leads to potential instability, semiperiodic or chaotic behavior and, thus, circuit malfunction. The aim of this paper is to show by means of simulations and experimental results that nonlinear phenomena, which cannot be predicted by the common small signal analysis, may appear in this kind of circuits when circuit parameters are varied.

  • Introduction to the special section on smart devices for renewable energy systems

     Cecati, Carlo; Guinjoan Gispert, Francisco; Siano, Pierluig; Spagnuolo, Giovanni
    IEEE transactions on industrial electronics
    Date of publication: 2013-03
    Journal article

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    The papers in this special section focus on the topics of smart devices and applications for renewable energy systems.

    The papers in this special section focus on the topics of smart devices and applications for renewable energy systems.

  • Power adaptor device for domestic DC microgrids based on commercial MPPT inverters

     Valderrama Blavi, H.; Bosque, J.M.; Guinjoan Gispert, Francisco; Marroyo, L.; Martínez Salamero, Luis
    IEEE transactions on industrial electronics
    Date of publication: 2013
    Journal article

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    This paper presents a power adaptor device, referred to as smart panel device, allowing the connection of additional energy sources and storage elements to a domestic photovoltaic (PV) grid-connected system. The adaptor output port is designed to behave as a power source/sink, thus enabling its hot-swap parallel connection to renewable power sources without modifying their maximum power point (MPP). Moreover, the adaptor device features a power characteristic with a single controllable MPP and allows the control of the injected power within the operating range of the dc¿ac grid-connected inverter. The work presents the design principles of such device by describing the operation of a sliding- mode controlled quadratic-boost converter. The proper operation of the device is experimentally verified for several scenarios in a small PV-based microgrid system including a fuel-cell stack, a 1-kW three-phase wind turbine, a battery charger¿discharger, and commercial grid-connected PV inverters

    This paper presents a power adaptor device, referred to as smart panel device, allowing the connection of additional energy sources and storage elements to a domestic photovoltaic (PV) grid-connected system. The adaptor output port is designed to behave as a power source/sink, thus enabling its hot-swap parallel connection to renewable power sources without modifying their maximum power point (MPP). Moreover, the adaptor device features a power characteristic with a single controllable MPP and allows the control of the injected power within the operating range of the dc–ac grid-connected inverter. The work presents the design principles of such device by describing the operation of a sliding- mode controlled quadratic-boost converter. The proper operation of the device is experimentally verified for several scenarios in a small PV-based microgrid system including a fuel-cell stack, a 1-kW three-phase wind turbine, a battery charger–discharger, and commercial grid-connected PV inverters

  • An asynchronous finite-state-machine-based buck-boost converter for on-chip adaptive power supply

     Fernández, Daniel; Madrenas Boadas, Jordi; Alarcon Cot, Eduardo Jose
    Analog integrated circuits and signal processing
    Date of publication: 2013-01
    Journal article

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    In this paper we present an asynchronous finite-state machine digital controller co-integrated with an on-chip non-inverting buck-boost power converter with dynamic signal-tracking capabilities. The mostly-digital controller functionally implements a non-PWM zone-wise control law through asynchronous circuitry, thus exhibiting self-timed minimum latency and ultra low power operation due to gate switching activity. Experimental results on a 0.35 µm CMOS technology demonstrate an efficiency up to 80 % with a switching frequency of 2.86 MHz.

    In this paper we present an asynchronous finite-state machine digital controller co-integrated with an on-chip non-inverting buck-boost power converter with dynamic signal-tracking capabilities. The mostly-digital controller functionally implements a non-PWM zone-wise control law through asynchronous circuitry, thus exhibiting self-timed minimum latency and ultra low power operation due to gate switching activity. Experimental results on a 0.35 lm CMOS technology demonstrate an efficiency up to 80 % with a switching frequency of 2.86 MHz

  • Fast transient current-steering CMOS LDO regulator based on current feedback amplifier

     Saberkari, Alireza; Alarcon Cot, Eduardo Jose; Shokouhi, Shahriar B.
    Integration. The VLSI journal
    Date of publication: 2013-03
    Journal article

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    This paper presents a current-steering approach to implement a fast transient response low-dropout regulator (LDO) based on a current feedback amplifier (CFA) topology. The circuit does not require any internal compensation capacitor, being stable for a wide range of output load currents [0¿100 mA] and a 1 µF output capacitor. The CFA consists of an open-loop voltage follower with output local current¿current feedback based on a level-shifted flipped voltage follower (LSFVF) which is instrumental to achieve high regulation and fast transient response. The inverting output buffer stage of the CFA together with current-mirror-based driving of the power pass transistor results in high PSRR. Post-layout simulation results for a 0.35 µm CMOS process design reveal that the proposed LDO requires 59 µA quiescent current at no-load condition and at full-load condition has a current efficiency of 99.8%. For a 1 µF output capacitor, the maximum output voltage variation to a 0¿100 mA load transient with rise and fall times of 10 and 100 ns is only 3 mV, and the PSRR is smaller than -56 dB over the entire load current range.

    This paper presents a current-steering approach to implement a fast transient response low-dropout regulator (LDO) based on a current feedback amplifier (CFA) topology. The circuit does not require any internal compensation capacitor, being stable for a wide range of output load currents [0–100 mA] and a 1 μF output capacitor. The CFA consists of an open-loop voltage follower with output local current–current feedback based on a level-shifted flipped voltage follower (LSFVF) which is instrumental to achieve high regulation and fast transient response. The inverting output buffer stage of the CFA together with current-mirror-based driving of the power pass transistor results in high PSRR. Post-layout simulation results for a 0.35 μm CMOS process design reveal that the proposed LDO requires 59 μA quiescent current at no-load condition and at full-load condition has a current efficiency of 99.8%. For a 1 μF output capacitor, the maximum output voltage variation to a 0–100 mA load transient with rise and fall times of 10 and 100 ns is only 3 mV, and the PSRR is smaller than −56 dB over the entire load current range.

  • On modified Wien-bridge oscillator and astable oscillator

     Martínez García, Herminio
    Analog integrated circuits and signal processing
    Date of publication: 2013-04
    Journal article

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  • Detection techniques for diffusion-based molecular communication

     Llatser Marti, Ignacio; Cabellos Aparicio, Alberto; Pierobon, Massimiliano; Alarcon Cot, Eduardo Jose
    IEEE journal on selected areas in communications
    Date of publication: 2013-12-01
    Journal article

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    Nanonetworks, the interconnection of nanosystems, are envisaged to greatly expand the applications of nanotechnology in the biomedical, environmental and industrial fields. However, it is still not clear how these nanosystems will communicate among them. This work considers a scenario of Diffusion-based Molecular Communication (DMC), a promising paradigm that has been recently proposed to implement nanonetworks. In a DMC network, transmitters encode information by the emission of molecules which diffuse throughout the medium, eventually reaching the receiver locations. In this scenario, a pulse-based modulation scheme is proposed and two techniques for the detection of the molecular pulses, namely, amplitude detection and energy detection, are compared. In order to evaluate the performance of DMC using both detection schemes, the most important communication metrics in each case are identified. Their analytical expressions are obtained and validated by simulation. Finally, the scalability of the obtained performance evaluation metrics in both detection techniques is compared in order to determine their suitability to particular DMC scenarios. Energy detection is found to be more suitable when the transmission distance constitutes a bottleneck in the performance of the network, whereas amplitude detection will allow achieving a higher transmission rate in the cases where the transmission distance is not a limitation. These results provide interesting insights which may serve designers as a guide to implement future DMC networks. © 1983-2012 IEEE.

  • El concepto de Smart Metering en el nuevo escenario de distribución eléctrica

     Casellas Beneyto, Francisco; Pique Lopez, Robert; Velasco Quesada, Guillermo; Guinjoan Gispert, Francisco
    Electro noticias
    Date of publication: 2013-11
    Journal article

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  • 4H-SiC Integrated Circuits for High Temperature and Harsh Environment Applications  Open access

     Alexandru, Mihaela
    Defense's date: 2013-09-10
    Department of Electronic Engineering, Universitat Politècnica de Catalunya
    Theses

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    Silicon Carbide (SiC) has received a special attention in the last decades thanks to its superior electrical, mechanical and chemical proprieties. SiC is mostly used for applications where Silicon is limited, becoming a proper material for both unipolar and bipolar power device able to work under high power, high frequency and high temperature conditions. Aside from the outstanding theoretical and practical advantages still to be proved in SiC devices, the need for more accurate models for the design and optimization of these devices, along with the development of integrated circuits (ICs) on SiC is indispensable for the further success of modern power electronics. The design and development of SiC ICs has become a necessity since the high temperature operation of ICs is expected to enable important improvements in aerospace, automotive, energy production and other industrial systems. Due to the last impressive progresses in the manufacturing of high quality SiC substrates, the possibility of developing ICs applications is now feasible. SiC unipolar transistors, such as JFETs and MESFETs show a promising potential for digital ICs operating at high temperature and in harsh environments. The reported ICs on SiC have been realized so far with either a small number of elements, or with a low integration density. Therefore, this work demonstrates that by means of our SiC MESFET technology, multi-stage digital ICs fabrication containing a large number of 4H-SiC devices is feasible, accomplishing some of the most important ICs requirements. The ultimate objective is the development of SiC digital building blocks by transferring the Si CMOS topologies, hence demonstrating that the ICs SiC technology can be an important competitor of the Si ICs technology especially in application fields in which high temperature, high switching speed and harsh environment operations are required. The study starts with the current normally-on SiC MESFET CNM complete analysis of an already fabricated MESFET. It continues with the modeling and fabrication of a new planar-MESFET structure together with new epitaxial resistors specially suited for high temperature and high integration density. A novel device isolation technique never used on SiC before is approached. A fabrication process flow with three metal levels fully compatible with the CMOS technology is defined. An exhaustive experimental characterization at room and high temperature (300ºC) and Spice parameter extractions for both structures are performed. In order to design digital ICs on SiC with the previously developed devices, the current available topologies for normally-on transistors are discussed. The circuits design using Spice modeling, the process technology, the fabrication and the testing of the 4H-SiC MESFET elementary logic gates library at high temperature and high frequencies are performed. The MESFET logic gates behavior up to 300ºC is analyzed. Finally, this library has allowed us implementing complex multi-stage logic circuits with three metal levels and a process flow fully compatible with a CMOS technology. This study demonstrates that the development of important SiC digital blocks by transferring CMOS topologies (such as Master Slave Data Flip-Flop and Data-Reset Flip-Flop) is successfully achieved. Hence, demonstrating that our 4H-SiC MESFET technology enables the fabrication of mixed signal ICs capable to operate at high temperature (300ºC) and high frequencies (300kHz). We consider this study an important step ahead regarding the future ICs developments on SiC. Finally, experimental irradiations were performed on W-Schotthy diodes and mesa-MESFET devices (with the same Schottky gate than the planar SiC MESFET) in order to study their radiation hardness stability. The good radiation endurance of SiC Schottky-gate devices is proven. It is expected that the new developed devices with the same W-Schottky gate, to have a similar behavior in radiation rich environments.

  • Advanced AlGaN/GaN HEMT technology, design, fabrication and characterization  Open access

     Fontserè Recuenco, Abel
    Defense's date: 2013-07-23
    Department of Electronic Engineering, Universitat Politècnica de Catalunya
    Theses

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    Nowadays, the microelectronics technology is based on the mature and very well established silicon (Si) technology. However, Si exhibits some important limitations regarding its voltage blocking capability, operation temperature and switching frequency. In this sense, Gallium Nitride (GaN)-based high electron mobility transistors (HEMTs) devices have the potential to make this change possible. The unique combination of the high-breakdown field, the high-channel electron mobility of the two dimensional electron gas (2DEG), and high-temperature of operation has attracted enormous interest from social, academia and industry and in this context this PhD dissertation has been made. This thesis has focused on improving the device performance through the advanced design, fabrication and characterization of AlGaN/GaN HEMTs, primarily grown on Si templates. The first milestone of this PhD dissertation has been the establishment of a know-how on GaN HEMT technology from several points of view: the device design, the device modeling, the process fabrication and the advanced characterization primarily using devices fabricated at Centre de Recherche sur l'Hétéro-Epitaxie (CRHEA-CNRS) (France) in the framework of a collaborative project. In this project, the main workhorse of this dissertation was the explorative analysis performed on the AlGaN/GaN HEMTs by innovative electrical and physical characterization methods. A relevant objective of this thesis was also to merge the nanotechnology approach with the conventional characterization techniques at the device scale to understand the device performance. A number of physical characterization techniques have been imaginatively used during this PhD determine the main physical parameters of our devices such as the morphology, the composition, the threading dislocations density, the nanoscale conductive pattern and others. The conductive atomic force microscopy (CAFM) tool have been widely described and used to understand the conduction mechanisms through the AlGaN/GaN Ohmic contact by performing simultaneously topography and electrical conductivity measurements. As it occurs with the most of the electronic switches, the gate stack is maybe the critical part of the device in terms of performance and longtime reliability. For this reason, how the AlGaN/GaN HEMT gate contact affects the overall HEMT behaviour by means of advanced characterization and modeling has been intensively investigated. It is worth mentioning that the high-temperature characterization is also a cornerstone of this PhD. It has been reported the elevated temperature impact on the forward and the reverse leakage currents for analogous Schottky gate HEMTs grown on different substrates: Si, sapphire and free-standing GaN (FS-GaN). The HEMT' forward-current temperature coefficients (T^a) as well as the thermal activation energies have been determined in the range of 25-300 ºC. Besides, the impact of the elevated temperature on the Ohmic and gate contacts has also been investigated. The main results of the gold-free AlGaN/GaN HEMTs high-voltage devices fabricated with a 4 inch Si CMOS compatible technology at the clean room of the CNM in the framework of the industrial contract with ON semiconductor were presented. We have shown that the fabricated devices are in the state-of-the-art (gold-free Ohmic and Schottky contacts) taking into account their power device figure-of-merit ((VB^2)/Ron) of 4.05×10^8 W/cm^2. Basically, two different families of AlGaN/GaN-on-Si MIS-HEMTs devices were fabricated on commercial 4 inch wafers: (i) using a thin ALD HfO2 (deposited on the CNM clean room) and (ii) thin in-situ grown Si3N4, as a gate insulator (grown by the vendor). The scientific impact of this PhD in terms of science indicators is of 17 journal papers (8 as first author) and 10 contributions at international conferences.

  • 1st European award for best practices for the integration of Sustainable Human Development (SHD) into technology/engineering education

     Alier Forment, Marc; Cabre Garcia, Jose Maria; Franquesa Griso, David; Garcia Almiñana, Jordi; García García, Helena; Lopez Alvarez, David; Sanchez Carracedo, Fermin; Vidal Lopez, Eva Maria
    Award or recognition

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  • MACHREK ENERGY DEVELOPMENT

     Martínez García, Herminio; Pique Lopez, Robert; Velasco Quesada, Guillermo; Guinjoan Gispert, Francisco
    Participation in a competitive project

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  • Chaos in switching converters for power management: designing for prediction and control

     Rodriguez Vilamitjana, Enric; El Aroudi, Abdelali; Alarcon Cot, Eduardo Jose
    Date of publication: 2013-01-15
    Book

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  • Diseño de una plataforma docente para el estudio de los sistemas de recolección de energía (energy harvesting) en los grados de ingeniería

     Martínez García, Herminio
    Spanish-Portuguese Conference on Electrical Engineering
    Presentation's date: 2013-07-04
    Presentation of work at congresses

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    El presente artículo presenta el diseño e implementación física de una plataforma docente recolectora y acondicionadora de energía práctica para aplicaciones de energy harvesting. Concretamente, muestra la realización de un sistema de acondicionamiento de energía solar fotovoltaica a partir de un modelo concreto de panel solar. Con el fin de conseguir una plataforma lo más eficiente posible, se ha implementado un sistema de seguimiento del punto de máxima potencia (MPPT) del panel fotovoltaico que optimiza el rendimiento del mismo, adentrando, a su vez, al estudiante de Ingeniería en este tipo de algoritmos. Además, la plataforma recolectora posee regulación de salida, ofreciendo así una tensión de salida constante, independientemente tanto de variaciones de carga como de la tensión de entrada.

  • Access to the full text
    RF performance projections of graphene FETs vs. silicon MOSFETs  Open access

     Rodriguez Duenas, Saul; Vaziri, Sam; Ostling, Mikael; Rusu, Ana; Alarcon Cot, Eduardo Jose; Lemme, Max
    ECS solid state letters
    Date of publication: 2012-08
    Journal article

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    A graphene field-effect-transistor (GFET) model calibrated with extracted device parameters and a commercial 65 nm silicon MOSFET model are compared with respect to their radio frequency behavior. GFETs slightly lag behind CMOS in terms of speed despite their higher mobility. This is counterintuitive, but can be explained by the effect of a strongly nonlinear voltage-dependent gate capacitance. GFETs achieve their maximum performance only for narrow ranges of V-DS and I-DS, which must be carefully considered for circuit design. For our parameter set, GFETs require at least mu = 3000 cm(2) V-1 s(-1) to achieve the same performance as 65 nm silicon MOSFETs.

    A graphene field-effect-transistor (GFET) model calibrated with extracted device parameters and a commercial 65 nm silicon MOSFET model are compared with respect to their radio frequency behavior. GFETs slightly lag behind CMOS in terms of speed despite their higher mobility. This is counterintuitive, but can be explained by the effect of a strongly nonlinear voltage-dependent gate capacitance. GFETs achieve their maximum performance only for narrow ranges of VDS and IDS, which must be carefully considered for circuit design. For our parameter set, GFETs require at least μ = 3000 cm2 V−1 s−1 to achieve the same performance as 65 nm silicon MOSFETs.

  • Analysis of limit cycles in a PI digitally controlled buck converter

     Bradley, D.; Alarcon Cot, Eduardo Jose; Feely, Orla
    IEEE International Symposium on Circuits and Systems
    Presentation's date: 2012-05-23
    Presentation of work at congresses

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    Digital control of power converters has been an area of considerable research interest in recent times. One of the problems which arises in these systems is that of the limit cycle oscillations that occur due to quantization in the feedback loop. This paper investigates the limit cycle oscillations that occur in the digitally controlled version of the buck converter with a proportional-integral controller. The amplitude and frequency of the oscillations that may occur on two duty cycle levels are investigated and related to the controller gain parameters. The analysis shows that it is not possible to guarantee that limit cycle oscillations on two levels will not occur simply by adjusting the gain parameters, and yields a condition which will prevent oscillations on two levels from occurring.

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    Estrategia de control para el equilibrado de corriente en transistores IGBT conectados en paralelo  Open access

     Perez Delgado, Raul; Roman Lumbreras, Manuel; Velasco Quesada, Guillermo
    Seminario Anual de Automática, Electrónica Industrial e Instrumentación
    Presentation's date: 2012-07-11
    Presentation of work at congresses

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    En este artículo se realiza un breve estudio sobre las características que influyen en el reparto de corriente entre semiconductores conectados en paralelo. El estudio se centra en el reparto de corriente en transistores IGBT conectados en paralelo y los mecanismos que permiten compensar dicho reparto. Para ello se proponen dos estrategias de control para el equilibrado de corriente que están basadas en un caso en el cálculo del valor medio de la corriente y en el otro, en la asociación de parejas de transistores. Finalmente se presentan resultados experimentales basados en las estrategias de control propuestas.

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    Chaos controller for switching regulators aiming enhanced design-space towards miniaturization  Open access

     Rodríguez Rodríguez, Enric; El Aroudi, Abdelali; Martínez García, Herminio; Poveda Lopez, Alberto; Iu, H.; Alarcon Cot, Eduardo Jose
    International Symposium on Nonlinear Theory and its Applications
    Presentation's date: 2012-10-25
    Presentation of work at congresses

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    This paper tackles the control of fast-scale instabilities in a buck switching power converter aiming to expand its design-space towards miniaturization. After briefly revisiting the working principle of existing chaos controllers, the paper explores an alternative approach based on amplifying the harmonic at the switching frequency. Numerical simulations show that the proposed controller can concurrently improve both fast-scale and slow-scale stability margins. Finally, the paper proposes a chaos controller combined with an output ripple reduction network and studies their interaction with the aim of achieving both low-ripple and improved stability.

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    Diseño e implementación de un amplificador híbrido lineal¿conmutado con amplio margen de salida  Open access

     Martínez García, Herminio
    Seminario Anual de Automática, Electrónica Industrial e Instrumentación
    Presentation's date: 2012-07-12
    Presentation of work at congresses

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    El presente trabajo presenta una técnica de diseño alternativa a los clásicos amplificadores de potencia en clase D. Como es sabido, éstos están basados en estructuras convertidoras continua–continua (DC/DC) con control PWM, en los que la señal de referencia que fija el ciclo de trabajo de los interruptores del amplificador es la propia señal de audio a amplificar. En la técnica mostrada, se hace uso de un amplificador en clase AB auxiliar, cuyo objetivo es obtener una señal de salida proporcional a la de entrada (señal a amplificar), libre de rizados espúreos y transitorios. Además, un convertidor conmutado, en paralelo con el amplificador en clase AB, permite proporcionar prácticamente la totalidad de la corriente demandada por la carga. La finalidad del conjunto es la de obtener altos rendimientos, propios de los amplificadores en clase D, pero aprovechando las excelentes características de inexistencia de rizados y elevada velocidad que poseen los amplificadores en clase AB.

  • Design of a 4.5-V, 450-mA low-dropout voltage linear regulator based on a cascoded OTA

     Martínez García, Herminio
    Seminario Anual de Automática, Electrónica Industrial e Instrumentación
    Presentation's date: 2012-07-12
    Presentation of work at congresses

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  • CMOS fast transient low-dropout regulator

     Saberkari, Alireza; Alarcon Cot, Eduardo Jose; Shokouhi, Shahriar B.
    Iranian Conference Electrical Engineering
    Presentation's date: 2012
    Presentation of work at congresses

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    In this paper a fast transient response CFA-based low-dropout regulator (LDO) is introduced. The circuit is stable for 0-100mA output load current and a 1μF output capacitor without any internal compensation. The CFA consists of a voltage follower with output local current-current feedback based on a level-shifted flipped voltage follower (LSFVF) which is instrumental to achieve high regulation and fast transient response. The inverting output buffer stage of the CFA together with current-mirror-based driving of the pass transistor results in high PSRR. Full transistor-level simulation results for an AMS 0.35μm CMOS process design reveal that the proposed LDO dissipates 58μA quiescent current at no-load condition and in worst case conditions has a current efficiency of 99.8%. For a 1μF output capacitor, the maximum output voltage variation to a 0-100mA load transient with rise and fall time of 10 and 100ns is only 2.5mV, and the PSRR is smaller than -58dB over the entire load current range.

  • Electronically tunable switch-mode high-efficiency adaptive band-pass filters for energy harvesting applications

     Gómez Cid-Fuentes, Raül; Martínez García, Herminio; Poveda Lopez, Alberto; Alarcon Cot, Eduardo Jose
    IEEE International Symposium on Circuits and Systems
    Presentation's date: 2012-05-21
    Presentation of work at congresses

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