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  • On the Scalability Limits of Communication Networks to the Nanoscale  Open access

     Llatser Marti, Ignacio
    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.

    Nanosystems, integrated systems with a total size of a few micrometers, are capable of interacting at the nanoscale, but their short operating range limits their usefulness in practical macro-scale scenarios. Nanonetworks, the interconnection of nanosystems, will extend their range of operation by allowing communication among nanosystems, thereby greatly enhancing their potential applications. In order to integrate communication capabilities into nanosystems, their communication subsystem needs to shrink to a size of a few micrometers. There are doubts about the feasibility of scaling down current metallic antennas to such a small size, mainly because their resonant frequency would be extremely high (in the optical domain) leading to a large free-space attenuation of the radiated EM waves. In consequence, as an alternative to implement wireless communications among nanosystems, two novel paradigms have emerged: molecular communication and graphene-enabled wireless communications. On the one hand, molecular communication is based on the exchange of molecules among nanosystems, inspired by communication among living cells. In Diffusion-based Molecular Communication (DMC), the emitted molecules propagate throughout the environment following a diffusion process until they reach the receiver. On the other hand, graphene, a one-atom-thick sheet of carbon atoms, has been proposed to implement graphene plasmonic RF antennas, or graphennas. Graphennas with a size in the order of a few micrometers show plasmonic effects which allow them to radiate EM waves in the terahertz band. Graphennas are the enabling technology of Graphene-enabled Wireless Communications (GWC). In order to answer the question of how communication networks will scale when their size shrinks, this thesis presents a scalability analysis of the performance metrics of communication networks to the nanoscale, following a general model with as few assumptions as possible. In the case of DMC, two detection schemes are proposed: amplitude detection and energy detection. Key performance metrics are identified and their scalability with respect to the transmission distance is found to differ significantly from the case of traditional wireless communications. These unique scaling trends present novel challenges which require the design of novel networking protocols specially adapted to DMC networks. The analysis of the propagation of plasmonic waves in graphennas allows determining their radiation performance. In particular, the resonant frequency of graphennas is not only lower than in metallic antennas, but it also increases more slowly as their length is reduced to the nanoscale. Moreover, the study of parameters such as the graphenna dimensions, the relaxation time of graphene and the applied chemical potential shows the tunability of graphennas in a wide frequency range. Furthermore, an experimental setup to measure graphennas based on feeding them by means of a photoconductive source is described. The effects of molecular absorption in the short-range terahertz channel, which corresponds to the expected operating scenario of graphennas, are analyzed. Molecular absorption is a process in which molecules present in the atmosphere absorb part of the energy of the terahertz EM waves radiated by graphennas, causing impairments in the performance of GWC. The study of molecular absorption allows quantifying this loss by deriving relevant performance metrics in this scenario, which show novel scalability trends as a function of the transmission distance with respect to the case of free-space propagation. Finally, the channel capacity of GWC is found to scale better as the antenna size is reduced than in traditional wireless communications. In consequence, GWC will require lower transmission power to achieve a given performance target. These results establish a general framework which may serve designers as a guide to implement wireless communication networks among nanosystems.

  • Transferencia de energía inalámbrica: acoplamiento inductivo resonante

     Poveda López, Alberto; Vidal Lopez, Eva Maria; Martínez García, Herminio; Alarcon Cot, Eduardo Jose
    Competitive project

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  • Temperature gradient sensor from pulsed power supply duty cycle in ultra-low-power energy harvesting system

     Jove Casulleras, Roger; Ramos Castro, Juan Jose; Corimanya, H; Camps Carmona, Adriano Jose; Alarcon Cot, Eduardo Jose; Amezaga Sarries, Adria; Bou Balust, Elisenda
    Electronics Letters
    Vol. 50, num. 11, p. 826-828
    DOI: 10.1049/el.2014.0399
    Date of publication: 2014-05-22
    Journal article

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    Directly interfacing sensors that link sensors to micro-controllers without a signal conditioning circuit or an analogue-to-digital converter on the one side and energy harvesting systems on the other side are two key enabling technologies to create self-powered autonomous low-cost and low-maintenance sensor networks. In this reported work, both technologies are concurrently combined in such a way that the duty cycle of the pulsed power supply provided by the harvesting system itself yields in turn a temperature gradient sensor functionality. Originally conceived to power a low-power satellite beacon in a CubeSat project, it has found application, among other applications, in automatic air conditioning and heating systems aiming smart buildings.

  • Cooperative signal amplification for molecular communication in nanonetworks

     Abadal Cavalle, Sergi; Llatser Marti, Ignacio; Alarcon Cot, Eduardo Jose; Cabellos Aparicio, Alberto
    Wireless networks
    Vol. 20, num. 6, p. 1611-1626
    DOI: 10.1007/s11276-014-0696-z
    Date of publication: 2014-08-01
    Journal article

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    Nanotechnology is enabling the development of devices in a scale ranging from a few to hundreds of nanometers. Communication between these devices greatly expands the possible applications, increasing the complexity and range of operation of the system. In particular, the resulting nanocommunication networks (or nanonetworks) show great potential for applications in the biomedical field, in which diffusion-based molecular communication is regarded as a promising alternative to EM-based solutions due to the bio-stability and energy-related requirements of this scenario. However, molecular signals suffer a significant amount of attenuation as they propagate through the medium, thus limiting the transmission range. In this paper, a signal amplification scheme for molecular communication nanonetworks is presented wherein a group of emitters jointly transmits a given signal after achieving synchronization. This is achieved by means of quorum sensing (QS), a method used by bacteria to both sense their population and coordinate their actions. By using the proposed methodology, the transmission range is extended proportionally to the number of synchronized emitters. An analytical model of QS is provided and validated through simulation. This model is the main contribution of this work and accounts for the activation threshold (which will eventually determine the resulting amplification level) and the delay of the synchronization process.

  • Design and comparison of flipped active inductors with high quality factors

     Saberkari, Alireza; Ziabakhsh, Soheil; Martínez García, Herminio; Alarcon Cot, Eduardo Jose
    Electronics Letters
    Vol. 50, num. 13, p. 925-927
    DOI: 10.1049/el.2014.0488
    Date of publication: 2014-05-19
    Journal article

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    A new design based on the flipped-structure for RF active inductors is presented. The conventional flipped-active inductor (FAI) composed of only two transistors is considered as a starting structure. However, it suffers from low-voltage swing, which increases the nonlinearity. Additionally, it requires high power consumption to achieve adequate inductance and quality factor values. A circuit topology named cascoded FAI (CASFAI) based on the basic FAI is proposed. A common-gate transistor added in the feedback path of the proposed CASFAI results in an increase of the voltage swing and linearity as well as the feedback gain. The performance metrics of such active inductors are benchmarked by analytical models and validated in the ADS using a 0.18 µm CMOS process. The results indicate that the CASFAI can achieve a notably higher quality factor and higher inductance values while consuming less power in comparison to the basic FAI.

  • N3Sim: Simulation framework for diffusion-based molecular communication nanonetworks

     Llatser Marti, Ignacio; Demiray, D.; Cabellos Aparicio, Alberto; Altilar, D. Turgay; Alarcon Cot, Eduardo Jose
    Simulation modelling practice and theory
    Vol. 42, p. 210-222
    DOI: 10.1016/j.simpat.2013.11.004
    Date of publication: 2014-03-01
    Journal article

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    Diffusion-based molecular communication is a promising bio-inspired paradigm to implement nanonetworks, i.e., the interconnection of nanomachines. The peculiarities of the physical channel in diffusion-based molecular communication require the development of novel models, architectures and protocols for this new scenario, which need to be validated by simulation. N3Sim is a simulation framework for nanonetworks with transmitter, receiver, and harvester nodes using Diffusion-based Molecular Communication (DMC). In DMC, transmitters encode the information by releasing molecules into the medium, thus varying their local concentration. N3Sim models the movement of these molecules according to Brownian dynamics, and it also takes into account their inertia and the interactions among them. Harvesters collect molecules from the environment to reuse them for later transmissions. Receivers decode the information by sensing the particle concentration in their neighborhood. The benefits of N3Sim are multiple: the validation of channel models for DMC and the evaluation of novel modulation schemes are just a few examples. (C) 2013 Elsevier B.V. All rights reserved.

  • Design-oriented analysis of quantization-induced limit cycles in a multiple-sampled digitally controlled buck converter

     Bradley, Mark; Alarcon Cot, Eduardo Jose; Feely, Orla
    IEEE transactions on circuits and systems I: regular papers
    Vol. 61, num. 4, p. 1192-1205
    DOI: 10.1109/TCSI.2013.2283671
    Date of publication: 2014-04-01
    Journal article

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    Digital control of switching power converters is an area which has seen increased attention in recent years. However, quantization in the feedback loop from the analog-to-digital (A/D) converter and the digital pulse width modulator (DPWM) may cause limit cycle oscillations to manifest, which are generally seen as being undesirable. This paper presents an analysis of the limit cycle behavior found in a multiple-sampled digitally controlled buck converter. The limit cycles which may arise in the system are characterized and conditions to prevent these oscillations from occurring are presented. © 2004-2012 IEEE.

  • Performance analysis of dual-frequency buck converter for integrated power management

     Shirmohammadli, V.; Saberkari, Alireza; Alarcon Cot, Eduardo Jose
    Power Electronics, Drive Systems and Technologies Conference
    p. 402-407
    DOI: 10.1109/PEDSTC.2014.6799409
    Presentation's date: 2014-02
    Presentation of work at congresses

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    The use of dual-frequency (DF) buck converter architecture consisting of a merged structure of high and low frequency buck cells is presented as a candidate topology for integrated power management to obtain favorable tradeoffs in terms of efficiency, switching ripple, and bandwidth. It is shown that having two degrees of freedom in designing the DF buck helps to achieve high efficiency and low output ripples, simultaneously. A comparison analysis is done with regards to the aforementioned performance indexes with the standard and three-level buck converters and the results are validated in HSPICE in a 0.35 µm CMOS process.

  • Class E2 resonant non-radiative wireless power transfer link: a design-oriented joint circuit-system co-characterization approach

     Bou Balust, Elisenda; Nagashima, Tomoharu; Sekiya, Hiroo; Alarcon Cot, Eduardo Jose
    International Multi-Conference on Systems, Signals and Devices
    p. 1-4
    DOI: 10.1109/SSD.2014.6808902
    Presentation's date: 2014-02-11
    Presentation of work at congresses

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    Resonant Inductive CouplingWireless Power Transfer is a key technology to provide an efficient and harmless wireless energy channel to consumer electronics, biomedical implants and wireless sensor networks. Many applications have been proposed for this technology, but the interplay between the Resonant Inductive Coupling magnetic link and the power electronics front-end is still unclear. In this paper, we propose a design-oriented joint circuit-system approach to design a high-efficiency resonant inductive coupling wireless power transfer link embedded in a class E2 DC-DC converter. © 2014 IEEE.

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

     Rodriguez Vilamitjana, Enric; El Aroudi, Abdelali; Alarcon Cot, Eduardo Jose
    DOI: 10.1007/978-1-4614-2128-3
    Date of publication: 2013-01-15
    Book

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  • 8th Google Faculty Reserach Award

     Alarcon Cot, Eduardo Jose; Camps Carmona, Adriano Jose; Ramos Castro, Juan Jose
    Award or recognition

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  • High slew rate current mode transconductance error amplifier for low quiescent current output-capacitorless CMOS LDO regulator

     Fathipour, Rasoul; Saberkari, Alireza; Martínez García, Herminio; Alarcon Cot, Eduardo Jose
    Integration. The VLSI journal
    Vol. 47, num. 2, p. 204-210
    DOI: 10.1016/j.vlsi.2013.10.005
    Date of publication: 2013-11-08
    Journal article

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    This paper presents a CMOS low quiescent current output-capacitorless low-dropout regulator (LDO) based on a high slew rate current mode transconductance amplifier (CTA) as error amplifier. Using local common-mode feedback (LCMFB) in the proposed CTA, the order of transfer characteristic of the circuit is increased. Therefore, the slew rate at the gate of pass transistor is enhanced. This improves the LDO load transient characteristic even at low quiescent current. The proposed LDO topology has been designed and post simulated in HSPICE in a 0.18 µm CMOS process to supply the load current between 0-100 mA. The dropout voltage of the LDO is set to 200 mV for 1.2-2 V input voltage. Post-layout 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. The total quiescent current of the LDO including the current consumed by the reference buffer circuit is only 3.7 µA. A final benchmark comparison considering all relevant performance metrics is presented.

  • 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
    Vol. 74, num. 1, p. 227-238
    DOI: 10.1007/s10470-012-9975-8
    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
    Vol. 46, num. 2, p. 165-171
    DOI: 10.1016/j.vlsi.2012.02.001
    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.

  • 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
    Vol. 31, num. 12, p. 726-734
    DOI: 10.1109/JSAC.2013.SUP2.1213005
    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.

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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
    p. 1484-1487
    DOI: 10.1109/ISCAS.2013.6572138
    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.

  • Estudio y simulación de MOSFETs de carburo de silicio (SiC) mediante PSIM para un inversor fotovoltaico en puente completo conectado a red

     Chavarria Roe, Javier; Biel Sole, Domingo; Guinjoan Gispert, Francisco; Poveda Lopez, Alberto; Alarcon Cot, Eduardo Jose; Massana, Francisco
    Seminario Anual de Automática, Electrónica Industrial e Instrumentación
    p. 50
    Presentation's date: 2013-07-11
    Presentation of work at congresses

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    El presente artículo muestra, mediante simulación PSIM, el impacto de la utilización de MOSFETs de Carburo de Silicio (SiC) en la eficiencia de inversores fotovoltaicos en puente completo conectados a red. Las simulaciones presentadas utilizan la facilidad ¿Device Database Editor¿ para construir modelos de MOSFET tanto de Si como de SiC y comparan diversos parámetros como la eficiencia o el rizado de la corriente de salida. Estas simulaciones también permiten establecer un método de diseño de la frecuencia de conmutación y del inductor de salida del inversor.

  • 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
    p. 49-52
    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.

  • 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
    p. 1554-1559
    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.

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

     Martínez García, Herminio; El Aroudi, Abdelali; Alarcon Cot, Eduardo Jose; Poveda Lopez, Alberto
    Seminario Anual de Automática, Electrónica Industrial e Instrumentación
    p. 1-4
    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.

  • 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
    p. 2783-2786
    DOI: 10.1109/ISCAS.2013.6572456
    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.

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    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
    p. 1-9
    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.

  • 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
    p. 29-32
    DOI: 10.1109/ISCAS.2013.6571774
    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.

  • 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
    p. 1-4
    DOI: 10.1109/ECCTD.2013.6662278
    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.

  • 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
    p. 131-136
    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

  • Distincio Jaume Vicenç Vives

     Bragos Bardia, Ramon; Alarcon Cot, Eduardo Jose; Camps Carmona, Adriano Jose; Consolacion Segura, Carolina Maria; Oliveras Verges, Albert; Pegueroles Valles, Josep Rafel; Sayrol Clols, Elisa
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  • 15è. Premi UPC a la Qualitat en la Docència Universitària

     Bragos Bardia, Ramon; Sayrol Clols, Elisa; Alarcon Cot, Eduardo Jose; Camps Carmona, Adriano Jose; Pegueroles Valles, Josep Rafel; Oliveras Verges, Albert; Consolacion Segura, Carolina Maria
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  • 2012 SAMSUNG Global Research Outreach GIFT

     Alarcon Cot, Eduardo Jose; Cabellos Aparicio, Alberto
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  • Graphene-enabled hybrid architectures for multiprocessors: bridging nanophotonics and nanoscale wireless communication

     Abadal Cavalle, Sergi; Cabellos Aparicio, Alberto; Lazaro Villa, Jose Antonio; Alarcon Cot, Eduardo Jose; Sole Pareta, Josep
    International Conference on Transparent Optical Networks
    p. 1-4
    Presentation's date: 2012-07-04
    Presentation of work at congresses

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  • Networking challenges and principles in diffusion-based molecular communication

     Llatser Marti, Ignacio; Cabellos Aparicio, Alberto; Alarcon Cot, Eduardo Jose
    IEEE Wireless communications
    Vol. 19, num. 5, p. 36-41
    Date of publication: 2012-10
    Journal article

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    Nanotechnology has allowed building nanomachines capable of performing simple tasks, such as sensing, data storage, and actuation. Nanonetworks, networks of nanomachines, will allow cooperation and information sharing among them, thereby greatly expanding the applications of nanotechnology in the biomedical, environmental,and industrial fields. One of the most promising paradigms to implement nanonetworks is diffusion-based molecular communication (DMC). In DMC, nanomachines transmit information by the emission of molecules that diffuse throughout the medium until they reach their destination. Most of the existing literature in DMC has focused on the analysis of its physical channel. In this work, the key differences of the physical channel of DMC with respect to the wireless electromagnetic channel are reviewed with the purpose of learning how they impact the design of networks using DMC. In particular, we find that the uniqueness of the physical channel of DMC will require revisiting most of the protocols and techniques developed for traditional wireless networks in order to adapt them to DMC networks. Furthermore, guidelines for the design of a novel network architecture for DMC networks, including fundamental aspects such as coding, medium access control, addressing, routing and synchronization, are provided.

  • Instabilities in digitally controlled voltage-mode synchronous buck converter

     Dongsheng, Yu; Herbert, H. C. Iu; Hao, Chen; Rodriguez, E; Alarcon Cot, Eduardo Jose; El Aroudi, Abdelali
    International journal of bifurcation and chaos
    Vol. 22, num. 1, p. 1-12
    DOI: 10.1142/S0218127412500125
    Date of publication: 2012
    Journal article

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    In this paper, instabilities and bifurcation behavior in a DC–DC digitally controlled voltagemode synchronous buck converter (SBC) are studied. The bifurcation diagram of the system under a proportional-integral (PI) compensation is presented. Following the system mathematical description in the continuous time domain, the z-domain pulse transfer function is derived in terms of system parameters. The stability range of the design parameter is obtained in closed form by using the Jury test combined with the describing function (DF) method. Experimental measurements from a laboratory prototype are used to validate the theoretical predictions and the numerical simulations.

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    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
    Vol. 1, num. 5, p. 39-41
    DOI: 10.1149/2.001205ssl
    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 and evaluation of using a tuning inductance on the performance of gilbert cell-based CMOS sub-harmonic mixer

     Saberkari, Alireza; Shokouhi, Shahriar B.; Alarcon Cot, Eduardo Jose; Baghersalimi, Gholamreza
    Research Journal of Applied Sciences, Engineering and Technology
    Vol. 4, num. 5, p. 486-490
    Date of publication: 2012
    Journal article

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  • An ultralow-power mixed-signal back end for passive sensor UHF RFID transponders

     Rodríguez Rodríguez, J.A.; Delgado Restituto, M.; Masuch, J.; Rodriguez Perez, Alberto; Alarcon Cot, Eduardo Jose; Rodríguez Vázquez, Ángel
    IEEE transactions on industrial electronics
    Vol. 59, num. 2, p. 1310-1322
    DOI: 10.1109/TIE.2011.2159695
    Date of publication: 2012-02
    Journal article

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    This paper describes the design of mixed-signal back end for an ultrahigh-frequency sensor-enabled radio-frequency identification transponder in full compliance with the Electronic Product Code Class-1 Generation-2 protocol, defined in the standard ISO 18000-6C. The chip, implemented in a low-cost 0.35- μm CMOS technology process, includes a baseband processor, an analog-to-digital converter (ADC) to digitize the signal acquired from the external sensor, and some auxiliary circuitry for voltage regulation and reference generation. The proposed solution uses two different supply voltages, one for the processor and the other for the mixed-signal circuitry, and defines a novel communication protocol between both blocks so that analog readouts are minimally affected by the digital activity of the tag. The whole system was first functionally validated by exhaustively testing with external dc power supplies ten prototype samples, and then, the two main blocks, processor, and ADC were individually tested to assess their performance limits. Regarding the baseband processor, experiments were performed toward the calculation of its packet error rate (PER) under two typical biasing configurations of passive tags, using either crude clamps or regulators. It was found that the regulated biasing outperforms the clamping solution and obtains a PER of 3 × 10-3 with a supply voltage of 0.75 V. The current consumption of the processor during the reception and response to a Read command at maximum backward rate is only 2.2 μA from a 0.9-V supply. Regarding the ADC, it is a 10-b successive approximation register converter which obtains 9.41 b of effective resolution at 2-kS/s sampling frequency with a power consumption of 250 nW, including the dissipation of a current generation cell and the clock generation circuitry, from 1-V supply.

  • Power MOSFET technology roadmap toward high power density voltage regulators for next-generation computer processors

     López, Toni; Alarcon Cot, Eduardo Jose
    IEEE transactions on power electronics
    Vol. 27, num. 4, p. 2193-2203
    DOI: 10.1109/TPEL.2011.2165343
    Date of publication: 2012-04
    Journal article

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  • Graphene-based nano-patch antenna for terahertz radiation

     Llatser Marti, Ignacio; Kremers, Christian; Cabellos Aparicio, Alberto; Jornet, Josep Miquel; Alarcon Cot, Eduardo Jose; Chigrin, Dmitry N.
    Photonics and nanostructures. Fundamentals and applications
    Vol. 10, num. 4, p. 353-358
    DOI: 10.1016/j.photonics.2012.05.011
    Date of publication: 2012-10
    Journal article

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  • Radiation characteristics of tunable graphennas in the terahertz band

     Llatser Marti, Ignacio; Kremers, Christian; Chigrin, Dmitry N.; Jornet, Josep Miquel; Lemme, Max C.; Cabellos Aparicio, Alberto; Alarcon Cot, Eduardo Jose
    Radioengineering
    Vol. 21, num. 4, p. 1-8
    Date of publication: 2012-12
    Journal article

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  • 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
    p. 684-687
    DOI: 10.1109/ISCAS.2012.6272125
    Presentation's date: 2012-05-22
    Presentation of work at congresses

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    Wireless Sensor Networks (WSN) present a pending challenge for a complete deployability due to energy requirements. The Self-Powered WSN approach aims to extend the sensor node life by means of Energy Harvesting. The harvested energy presents an erratic behavior in both time and frequency. In this paper, a new concept of switch-mode electronically tunable band-pass filters is presented to adaptively follow the power source variations and to maximize the power transfer. To implement these switch-mode filters, three alternatives are presented. These filter topologies are modeled and evaluated. Additionally, some design guidelines are provided. The results show how these high efficiency topologies present a band-pass behavior whose center frequency can be electronically tuned over one decade. The results target the integration of these highefficiency switch-mode band-pass filters into the future harvesting front-ends.

  • Characterization of graphene-based nano-antennas in the terahertz band

     Llatser Marti, Ignacio; Kremers, Christian; Chigrin, Dmitry N.; Jornet, Josep Miquel; Lemme, Max C.; Cabellos Aparicio, Alberto; Alarcon Cot, Eduardo Jose
    European Conference on Antennas and Propagation
    p. 194-198
    DOI: 10.1109/EuCAP.2012.6206598
    Presentation's date: 2012-03-26
    Presentation of work at congresses

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  • Prospects of graphene-enabled wireless communications

     Llatser Marti, Ignacio; Abadal Cavalle, Sergi; Gómez Cid-Fuentes, Raül; Jornet, Josep Miquel; Cabellos Aparicio, Alberto; Alarcon Cot, Eduardo Jose; Sole Pareta, Josep; Akyildiz, Ian F.
    International Conference on GRAPHENE
    Presentation's date: 2012-04-10
    Presentation of work at congresses

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  • Ripple-based prediction of fast-scale instabilities in current mode controlled switching converters

     Rodríguez Rodríguez, Enric; Martínez García, Herminio; Guinjoan Gispert, Francisco; El Aroudi, Abdelali; Poveda Lopez, Alberto; Alarcon Cot, Eduardo Jose
    IEEE International Symposium on Circuits and Systems
    p. 688-691
    DOI: 10.1109/ISCAS.2012.6272126
    Presentation's date: 2012-05-22
    Presentation of work at congresses

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  • A design-oriented optimization framework for envelope trackers: Application to a sliding-mode control buck converter for EDGE

     Marco Platón, Lázaro; Poveda Lopez, Alberto; Guinjoan Gispert, Francisco; Maksimovic, Dragan; Alarcon Cot, Eduardo Jose
    International Power Electronics and Motion Control Conference
    p. 21-26
    Presentation's date: 2012-09
    Presentation of work at congresses

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  • Reactive power control for voltage support during type C voltage-sags

     Camacho Santiago, Antonio; Castilla Fernandez, Miguel; Miret Tomas, Jaume; Matas Alcala, Jose; Alarcon Cot, Eduardo Jose; Garcia de Vicuña Muñoz de la Nava, Jose Luis; Marti Colom, Pau
    Annual Conference of the IEEE Industrial Electronics Society
    p. 3462-3467
    DOI: 10.1109/IECON.2012.6389343
    Presentation's date: 2012-10-27
    Presentation of work at congresses

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  • Resonant pulse-shaping power supply for radar transmitters

     Bell Rodriguez, Miguel Victoria Ramo; Roberg, Michael; Pack, Riley; Garcia Fernandez, Pablo; Alarcon Cot, Eduardo Jose; Popoviç, Zoya; Maksimovic, Dragan
    International Power Electronics and Motion Control Conference
    p. LS5e.31-LS5e.37
    DOI: 10.1109/EPEPEMC.2012.6397484
    Presentation's date: 2012-09
    Presentation of work at congresses

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    The final radiofrequency power amplifier (PA) of a radar transmitter module is a large factor in system efficiency. Typical radar transmitter signals are frequency-modulated with constant-amplitude pulse envelopes in order to optimize efficiency, resulting in spectral broadening and power radiated outside of the radar frequency band. This paper demonstrates a PA with a dynamic power supply which enables high efficiency while reducing the spectral emissions. The resonant pulse-shaping power supply generates a raised-cosine pulse envelope waveform with efficiency greater than 90% and peak envelope power around 6 W. Measured results with a 2.14-GHz GaN power amplifier with an efficiency of 76% at peak power demonstrate over 67% transmitter efficiency.

  • Quorum sensing-enabled amplification for molecular nanonetworks

     Abadal Cavalle, Sergi; Llatser Marti, Ignacio; Alarcon Cot, Eduardo Jose; Cabellos Aparicio, Alberto
    IEEE International Workshop on Molecular and Nano Scale Communication
    p. 6162-6166
    DOI: 10.1109/ICC.2012.6364691
    Presentation's date: 2012-06
    Presentation of work at congresses

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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.

  • CMOS fast transient low-dropout regulator

     Saberkari, Alireza; Alarcon Cot, Eduardo Jose; Shokouhi, Shahriar B.
    Iranian Conference Electrical Engineering
    p. 105-108
    DOI: 10.1109/IranianCEE.2012.6292333
    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
    p. 684-687
    DOI: 10.1109/ISCAS.2012.6272125
    Presentation's date: 2012-05-21
    Presentation of work at congresses

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  • Fast transient response CFA-based LDO regulator

     Saberkari, Alireza; Martínez García, Herminio; Alarcon Cot, Eduardo Jose
    IEEE International Symposium on Circuits and Systems
    p. 3150-3153
    DOI: 10.1109/ISCAS.2012.6271990
    Presentation's date: 2012-05-22
    Presentation of work at congresses

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  • 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
    p. 628-631
    DOI: 10.1109/ISCAS.2012.6272110
    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.