E. Alarcon

Polytechnic University of Catalonia, Barcino, Catalonia, Spain

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Publications (174)84.67 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: It is a pleasure and a privilege to present to the readers of the Springer Journal on Analog Integrated Circuits and Signal Processing (ALOG) a selection of the papers from the 4th edition of the Latin America Symposium on Circuits and Systems—LASCAS 2013, held in February 2013 in the historical Peruvian city of Cuzco.The LASCAS Symposium is the premier event in circuits and systems in that region of the Americas. The papers selected by the Guest Editors fall in the focus of this Journal, and are among the 10 % top quality of the 155 papers submitted to LASCAS 2013, and were selected by rigorous reviewing. While LASCAS contemplates applications and digital systems, most of the papers in this Special Issue address analog circuits and systems, the themes of interest to ALOG Journal readers.From the 119 papers which were accepted and published in the IEEE LASCAS Proceedings, a total of 27 works were nominated and invited to submit a substantially improved manuscript on the same subject to ...
    Analog Integrated Circuits and Signal Processing 12/2014; · 0.40 Impact Factor
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    ABSTRACT: Energy-harvesting-enabled wireless sensor networks (EHE-WSN), despite their disruptive potential impact, still present several challenges precluding practical deployability. In particular, the low power density and random character of the ambient energy sources produce slow deep fadings in the energy that nodes harvest. Unfortunately, the capacity of the energy buffers is very limited, causing that, at some times, the node might interrupt its operation due to lack of stored energy. In this context, a general purpose framework for dimensioning the energy buffer is provided in this work. To achieve this, a dynamics-decoupled, multi-source capable energy model is presented, which can handle fast random patterns of the communications and the energy harvesting, while it can capture slow variations of the ambient energy in both time and space. By merging both dynamics, the model can more accurately evaluate the performance of the sensor node in terms of the energy storage capacity and to estimate the expected energy of the neighboring nodes. In order to evaluate the performance of the sensor node, a statistical unit for energy harvesting resources, referred as the Energy-Erlang (E2), has been defined. This unit provides a link between the energy model, the environmental harvested power and the energy buffer. The results motivate the study of the specific properties of the ambient energy sources before the design and deployment. By combining them in this general-purpose framework, electronics and network designers will have a powerful tool for optimizing resources in EHE-WSNs.
    Emerging and Selected Topics in Circuits and Systems, IEEE Journal on. 09/2014; 4(3):301-312.
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    ABSTRACT: 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.
    Electronics Letters 06/2014; 50(13):925-927. · 1.07 Impact Factor
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    ABSTRACT: Recent research in wireless power transfer (WPT) using resonant inductive coupling has demonstrated very high efficiencies at large distances compared to the transmitting element dimensions, thereby increasing the number of potential applications of WPT. Since resonant inductive coupling is a very multidisciplinary field of research, different approaches have been proposed to predict the behaviour of these systems from the physical theory of resonators (coupled-mode theory) and circuit theory. Although the equivalence of these models for a point-to-point link has already been studied together with the performance metrics Power Transferred to the Load (PTL) and Power Transfer Efficiency (PTE), the new challenges and applications of this technology emphasize the necessity of analytical models to predict and assess the behavior of Multiple Input - Multiple Output (MIMO) links. In this article we revisit the current analytical models from the MIMO perspective, derive the analytical equations for the equivalent performance metrics PTE and PTL and demonstrate how to maximize them in a non-radiative resonant wireless power transfer link from a circuit-centric point of view, providing design guidelines in terms of optimal source and load impedances. This work concludes with a prospective discussion on open challenges of WPT.
    2014 IEEE International Symposium on Circuits and Systems (ISCAS); 06/2014
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    ABSTRACT: Multi-source energy harvesters are gaining interest as a robust alternative to power wireless sensors, since the sensor node can maintain its operation regardless of the fact that one of its energy sources might be temporarily unavailable. Interestingly, and less explored, when the energy availability of the energy sources present large temporal variations, combining multiple energy sources reduce the overall sparsity. As a result, the performance of a multiple energy harvester powered sensor node is significantly better compared to a single energy source which harvests the same amount of energy. In this context, a circuit area optimization framework for multiple source energy harvesting powered systems is proposed. This framework takes advantage of this improvement in performance to provide the optimal amount of energy harvesters, the requirements of each energy harvester and the required energy buffer capacity, such that the overall area or volume is minimized. As the results show, by conducting a joint design of the energy harvesters and the energy buffer, the overall area or volume of a sensor node can be significantly reduced.
    2014 IEEE International Symposium on Circuits and Systems (ISCAS); 06/2014
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    ABSTRACT: In this work, a proof of concept prototype for a photovoltaic array emulator based on a DC-DC Boost converter is presented. This design arises from the need to study in the laboratory new PV inverters based on Silicon Carbide (SiC) devices in order to evaluate their performances. The lack of space for installation of real photovoltaic panels and the high costs of the commercial emulators lead to alternative systems which allow the reproduction of the characteristic curves of the panel arrays as well as their dependence on changing environmental conditions. The control algorithm designed for the emulator prototype is implemented by means of a field programmable gate array (FPGA). Experimental results confirm the proper operation of the PV emulator which is applied to a full-bridge single phase grid-connected inverter.
    2014 IEEE 23rd International Symposium on Industrial Electronics (ISIE); 06/2014
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    ABSTRACT: Coupled magnetic resonance is considered to be a key enabling technology for mid-range wireless power transfer. Models and systems have hitherto considered linear resonators as underlying dynamics, thereby limiting practical deployability due to the extreme sensitivity in front of parameter mismatch and resonance detuning. In this work, structural nonlinear modeling of constituent elements of the resonant link-resonant coils- is considered to unveil the existence of nonlinear dynamic regimes. The methodology considered to explore the nonlinear behavior is based on a behavioral model consisting of state equations, Floquet theory and Filippov method to study the stability of the periodic regime through the associated monodromy matrix. The ultimate aim of the investigation is a design-oriented parameter space exploration which characterizes the border of occurrence of the different dynamic modes in wireless power transfer links.
    2014 IEEE International Symposium on Circuits and Systems (ISCAS); 06/2014
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    ABSTRACT: 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.
    Electronics Letters 05/2014; 50(11):826-828. · 1.07 Impact Factor
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    ABSTRACT: In the upcoming many-core era, chip multiprocessor architectures will be composed of hundreds or even thousands of processor cores, which interact among them through an on-chip communication platform for synchronization and data coherency/consistency purposes. As the traffic generated within the chip becomes more multicast-intensive, it is necessary to conceive novel communication platforms that go beyond conventional schemes and guarantee multicast support with high throughput, low latency, and low power. Nanotechnology provides an opportunity within this context by virtue of terahertz graphene antennas, which could allow the integration of one antenna per core in a Graphene-enabled Wireless Network-on-Chip (GWNoC). However, it is essential to design an appropriate MAC protocol in order to fully benefit from this novel approach. To provide a first contribution in this direction, in this paper we design two baseline MAC protocols based on the well-known ALOHA and carrier sensing techniques. Their functionalities have been properly conceived by taking into account characteristics and requirements of future chip multiprocessors systems. Moreover, their performances have been evaluated by means of computer simulations under different chip configurations. Obtained results demonstrate the pros and cons of these simple contention-based MAC protocols and pave the way for the future exploration of the MAC design space.
    05/2014;
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    ABSTRACT: The internal nodes of switched capacitor converters can be used to provide multiple pulsed width modulated voltages that, in combination with filter inductors, can extend the available dc outputs. Such converter architecture requires models that accurately predict the behaviour of switched capacitor converters operated in current output mode. Based on the well-known output impedance model, a new circuit representation is proposed for converters with multiple current-loaded outputs. A characterization methodology is developed to determine the parameters of said model. Predictions of the new model compare favorably to circuit simulations and experimental measurements.
    2014 IEEE Applied Power Electronics Conference and Exposition - APEC 2014; 03/2014
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    ABSTRACT: This paper presents a low cost photovoltaic array emulator design based on a DC-DC Boost converter. This design arises from the need to study in the laboratory new PV inverters based on SiC devices in order to improve their performances. The lack of space for installation of real photovoltaic panels and the high costs of the commercial emulators require of alternative systems which allow the reproduction of the characteristic curves of the panels as well as their dependence on changing environmental conditions. The emulator design is applied to a full-bridge single phase grid-connected inverter. Simulation results are provided to confirm the proper operation of the PV emulator.
    2014 11th International Multi-Conference on Systems, Signals & Devices (SSD); 02/2014
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    ABSTRACT: 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. 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 11th International Multi-Conference on Systems, Signals & Devices (SSD); 02/2014
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    ABSTRACT: Typical radar transmitter signals are frequency-modulated with pulsed constant-amplitude envelopes in order to optimize radio-frequency power amplifier (RFPA) efficiency, which results in spectral broadening and power radiated outside of the radar frequency band. This problem can be alleviated by using an appropriately shaped pulse envelope, provided that high-efficiency operation of the radar transmitter is maintained. This paper introduces a pulse-shaping power supply for RFPAs in radar transmitters which enables high efficiency while reducing the spectral emissions. The pulse-shaping power supply is a simple switched resonant circuit capable of approximating a Gaussian pulse envelope waveform. Operating principles are presented and a state-plane-based design approach is described for the resonant pulse-shaping power supply, which enables improved waveform quality and efficiency. An experimental prototype with efficiency greater than 90% is used to supply a 2.14-GHz GaN RFPA. The RFPA efficiency of up to 76%, overall transmitter efficiency of up to 67%, and output signal having high spectral purity demonstrate feasibility of a high-efficiency, high-performance radar system.
    IEEE Transactions on Power Electronics 02/2014; 29(2):707-718. · 5.73 Impact Factor
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    ABSTRACT: 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.
    2014 5th Power Electronics, Drive Systems & Technologies Conference (PEDSTC); 02/2014
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    ABSTRACT: Graphene, owing to its ability to support plasmon polariton waves in the terahertz frequency range, enables the miniaturization of antennas to allow wireless communications among nanosystems. One of the main challenges in the demonstration of graphene antennas is finding suitable terahertz sources to feed the antenna. This paper estimates the performance of a graphene RF plasmonic micro-antenna fed with a photoconductive source. The terahertz source is modeled and, by means of a full-wave EM solver, the radiated power of the device is estimated with respect to material, laser illumination and antenna geometry parameters. The results show that the proposed device radiates terahertz pulses with an average power up to 1$\mu$W, proving the feasibility of feeding miniaturized graphene antennas with photoconductive materials.
    01/2014;
  • IEICE Proceeding Series. 01/2014; 1:622-627.
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    ABSTRACT: 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.
    IEEE Journal on Selected Areas in Communications 12/2013; 31(12):726-734. · 4.14 Impact Factor
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    ABSTRACT: A number of techniques have been recently proposed to implement molecular communication, a novel method which aims to implement communication networks at the nanoscale, known as nanonetworks. A common characteristic of these techniques is that their main resource consists of molecules, which are inherently discrete. This paper presents DIRECT, a novel networking model which differs from conventional models by the way of treating resources as discrete entities; therefore, it is particularly aimed to the analysis of molecular communication techniques. Resources can be involved in different tasks in a network, such as message encoding, they do not attenuate in physical terms and they are considered 100% reusable. The essential properties of DIRECT are explored and the key parameters are investigated throughout this paper.
    Nano Communication Networks 12/2013; 4(4):181–188.
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    ABSTRACT: Current trends in microprocessor architecture design are leading towards a dramatic increase of core-level parallelization, wherein a given number of independent processors or cores are interconnected. Since the main bottleneck is foreseen to migrate from computation to communication, efficient and scalable means of inter-core communication are crucial for guaranteeing steady performance improvements in many-core processors. As the number of cores grows, it remains unclear whether initial proposals, such as the Network-on-Chip (NoC) paradigm, will meet the stringent requirements of this scenario. This position paper presents a new research area where massive multicore architectures have wireless communication capabilities at the core level. This goal is feasible by using graphene-based planar antennas, which can radiate signals at the Terahertz band while utilizing lower chip area than its metallic counterparts. To the best of our knowledge, this is the first work that discusses the utilization of graphene-enabled wireless communication for massive multicore processors. Such wireless systems enable broadcasting, multicasting, all-to-all communication, as well as significantly reduce many of the issues present in massively multicore environments, such as data coherency, consistency, synchronization and communication problems. Several open research challenges are pointed out related to implementation, communications and multicore architectures, which pave the way for future research in this multidisciplinary area.
    IEEE Communications Magazine 11/2013; 51(11):137-143. · 4.46 Impact Factor
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    ABSTRACT: This paper surveys and discusses the state-of-the-art of integrated switched-capacitor and inductive power converters. After introducing applications that drive the need for integrated switching power converters, implementation issues to be addressed for integrated switched-capacitor and inductive converters are given, as well as design examples. At the end of this paper, a comprehensive set of integrated power converters are compared in terms of the main specifications and performance metrics, thereby allowing a categorization and providing application-oriented design guidelines.
    IEEE Transactions on Power Electronics 09/2013; 28(9):4156-4167. · 5.73 Impact Factor

Publication Stats

962 Citations
84.67 Total Impact Points

Institutions

  • 1996–2013
    • Polytechnic University of Catalonia
      • • Department of Electrical Engineering (DEE)
      • • Department of Electronic Engineering (EEL)
      Barcino, Catalonia, Spain
  • 2011
    • Escuela Universitaria de Ingeniería Técnica Industrial de Bilbao
      Bilbo, Basque Country, Spain
  • 2010
    • Georgia Institute of Technology
      • Broadband & Wireless Networking Laboratory
      Atlanta, Georgia, United States
  • 1998–2010
    • Universitat Rovira i Virgili
      • Department of Electronic, Electrical and Automatic Engineering (DEEEA)
      Tarragona, Catalonia, Spain
  • 2004–2008
    • University of Colorado at Boulder
      • Department of Electrical, Computer, and Energy Engineering (ECEE)
      Boulder, Colorado, United States
  • 2007
    • University of Texas at Dallas
      Richardson, Texas, United States