Eduard Alarcon

Polytechnic University of Catalonia, Barcino, Catalonia, Spain

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Publications (213)124.93 Total impact

  • No preview · Conference Paper · May 2016
  • [Show abstract] [Hide abstract] ABSTRACT: New exact critical conditions for predicting subharmonic instability in switching regulators are approximated by simple design-oriented expressions valid under practical conditions. These simplified expressions contain the ripple and slope information of the feedback control signal. Depending on the converter topology, the controller used and values of parasitic parameters, either the slope or the ripple can be dominant in predicting instability. A discussion on the validity of this interpretation is illustrated through six different examples of switching regulators using the concept of the spectral radius and the relative degree of the system loop. Using this approach, the boundary between the desired stable region and the subharmonic instability can be easily obtained. The theoretical results are validated by means of numerical simulations.
    No preview · Article · Apr 2016 · International Journal of Electronics
  • [Show abstract] [Hide abstract] ABSTRACT: The scalability of Network-on-Chip (NoC) designs has become a rising concern as we enter the manycore era. Multicast support represents a particular yet relevant case within this context, mainly due to the poor performance of NoCs in the presence of this type of traffic. Multicast techniques are typically evaluated using synthetic traffic or within a full system, which is either simplistic or costly, given the lack of realistic traffic models that distinguish between unicast and multicast flows. To bridge this gap, this paper presents a trace-based multicast traffic characterization, which explores the scaling trends of aspects such as the multicast intensity or the spatiotemporal injection distribution for different coherence schemes. This analysis is the basis upon which the concept of multicast source prediction is proposed, and upon which a multicast traffic model is built. Both aspects pave the way for the development and accurate evaluation of advanced NoCs in the context of manycore computing.
    No preview · Article · Jan 2016 · Computers & Electrical Engineering
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    Full-text · Article · Jan 2016 · IEEE Transactions on Parallel and Distributed Systems
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    [Show abstract] [Hide abstract] ABSTRACT: Wireless RF power transmission promises battery-less, resilient, and perpetual wireless sensor networks. Through the action of controllable Energy Transmitters (ETs) that operate at-a-distance, the sensors can be re-charged by harvesting the radiated RF energy. However, both the charging rate and effective charging range of the ETs are limited, and thus multiple ETs are required to cover large areas. While this action increases the amount of wireless energy injected into the network, there are certain areas where the RF energy combines destructively. To address this problem, we propose a duty-cycled random-phase multiple access (DRAMA). Non-intuitively, our approach relies on deliberately generating random interferences, both destructive and constructive, at the destination nodes. We demonstrate that DRAMA optimizes the power conversion efficiency, and the total amount of energy harvested. Through real-testbed experiments, we prove that our proposed scheme provides significant advantages over the current state of the art in our considered scenario, as it requires up to 70\% less input RF power to recharge the energy buffer of the sensor in the same time.
    Full-text · Article · Dec 2015
  • [Show abstract] [Hide abstract] ABSTRACT: This paper presents a design procedure of high-frequency loosely inductive coupled wireless power transfer (LIC-WPT) system based on class-E2 DC-DC converter, taking into account the power loss reduction of inverter, coupling part, and rectifier simultaneously. Analytical expressions including the dc-to-dc efficiency of the WPT system are derived and the efficiency deterioration mechanism is explained by the circuit model. Through the analytical expressions, the design procedure for satisfying both the class-E switching conditions and power loss reductions at the coupling part is proposed from the circuit-theory viewpoint. The class-E2 WPT system designed by the proposed design procedure achieves high dc-to-dc efficiency at low coupling coefficient, in particular, compared with those designed by the previous design strategies. The validity and effectiveness of the proposed design procedure were confirmed by PSpice simulations and circuit experiments.
    No preview · Article · Nov 2015 · Circuits and Systems I: Regular Papers, IEEE Transactions on
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    [Show abstract] [Hide abstract] ABSTRACT: An optimization of the current-to-voltage transfer characteristic of a graphene FET (GFET) compact model, based on drift-diffusion carrier transport, is presented. The improved accuracy at Dirac point extends the model usability for GFETs when scaling parameters, such as voltage supply, gate length, oxide thickness, and mobility, for circuit design exploration. The model's accuracy is demonstrated through fitting to GFETs processed in-house. The model has been written in a standard behavioral language, and extensively run in an analog circuit simulator for designing basic circuits, such as inverters and cascode cells, demonstrating its robustness.
    Full-text · Article · Nov 2015 · IEEE Transactions on Electron Devices
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    E. Rodriguez · E. Alarcón · H. H. C. Iu · A. El Aroudi
    [Show abstract] [Hide abstract] ABSTRACT: This paper deals with controllers of fast-scale instabilities in DC-DC switching power converters from a frequency domain standpoint with the aim of understanding their working principle and hence simplifying their design. Some approaches for controlling fast-scale instabilities and their limitations are revisited. Considering the frequency domain transfer function of already existing controllers, a simple and extended notch filter centered at half of the switching frequency is proposed to avoid these instabilities. However, a switching converter under this controller may still exhibit the undesired slow-scale instability. Accordingly, the paper explores an alternative approach based on amplifying the harmonic at the switching frequency. Numerical simulations show that the new proposed controller can concurrently improve both fast-scale and slow-scale stability margins. The results from the different controllers are contrasted in terms of stability boundaries, indicating that the last one presents a wider stability range.
    Full-text · Article · Oct 2015 · International Journal of Bifurcation and Chaos
  • Elisenda Bou-Balust · Aiguo Patrick Hu · Eduard Alarcon
    [Show abstract] [Hide abstract] ABSTRACT: Resonant inductive coupling wireless power transfer (RIC-WPT) is a leading field of research due to the growing number of applications that can benefit from this technology: from biomedical implants to consumer electronics, fractionated spacecraft, and electric vehicles, amongst others. However, applications are currently limited to point-to-point-links and do not target single input-multiple output (SIMO) scenarios. New challenges and applications of resonant non-radiative wireless power transfer emphasize the necessity to explore, predict, and assess the behavior of RIC-WPT in SIMO links. Moreover, new system-level metrics have to be derived to study the scalability of multi-point wireless power transfer applications and to provide design guidelines for these systems. In this article a single input-multiple output RIC-WPT system is modeled analytically from a circuit-centric point of view and validated using a finite element field solver. The analytical model and associated closed formulation is finally used to derive system-level metrics to predict the behavior and scalability of RIC SIMO systems, showcasing the results for an asymmetric SIMO scenario.
    No preview · Article · Oct 2015 · Circuits and Systems I: Regular Papers, IEEE Transactions on
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    [Show abstract] [Hide abstract] ABSTRACT: Broadcast traditionally has been regarded as a prohibitive communication transaction in multiprocessor environments. Nowadays, such a constraint largely drives the design of architectures and algorithms all-pervasive in diverse computing domains, directly and indirectly leading to diminishing performance returns as the many-core era is approaching. Novel interconnect technologies could help revert this trend by offering, among others, improved broadcast support, even in large-scale chip multiprocessors. This article outlines the prospects of wireless on-chip communication technologies pointing toward low-latency (a few cycles) and energy-efficient broadcast (a few picojoules per bit). It also discusses the challenges and potential impact of adopting these technologies as key enablers of unconventional hardware architectures and algorithmic approaches, in the pathway of significantly improving the performance, energy efficiency, scalability, and programmability of many-core chips.
    Full-text · Article · Sep 2015 · IEEE Micro
  • [Show abstract] [Hide abstract] ABSTRACT: This paper proposes the use of double-frequency (DF) buck converter architecture consisting of a merged structure of high and low frequency buck cells as a candidate topology for envelope elimination and restoration (EER) applications and integrated power supply of RF power amplifiers (RFPA) to obtain favorable tradeoffs in terms of efficiency, switching ripple, bandwidth, and tracking capability. It is shown that having two degrees of freedom in designing the DF buck helps to achieve high efficiency, low output ripples, and tracking capability with low ripples, simultaneously. A comparison analysis is done with regards to the mentioned performance indexes with the standard and three-level buck converters; in addition, the results are validated in HSPICE in BSIM3V3 0.35-µm CMOS process. Copyright © 2015 John Wiley & Sons, Ltd.
    No preview · Article · Aug 2015 · International Journal of Circuit Theory and Applications
  • [Show abstract] [Hide abstract] ABSTRACT: This paper presents the use of a new structure of active inductor named cascoded flipped-active inductor (CASFAI) in a T-type high-pass tunable output matching network of a class-E RF power amplifier (RFPA) to control the output power and enhance the efficiency. The designed CASFAI behaves as an inductor in the frequency range of 0–6.9 GHz, and has reached to a maximum quality factor of 4406, inductance value of 7.56 nH, 3rd order harmonic distortion better than −30 dB for 0 dBm input power, while consumes only 2 mW power. In order to consider the performance of the proposed active inductor-based tunable output matching network on the output power level and power added efficiency (PAE) of RFPA, the CASFAI is applied as a variable inductor to the output matching network of RFPA. The overall circuit is designed and validated in ADS in a 0.18 µm CMOS process and 1.5 V supply voltage. The results indicate that by increasing the inductance value of the matching network in constant operating frequency, the PAE peak moves from high power to low power levels without any degradation. Therefore, it is possible to maintain the power efficiency at the same maximum level for lower input drive levels.
    No preview · Article · Aug 2015 · Integration the VLSI Journal
  • [Show abstract] [Hide abstract] ABSTRACT: New trends such as satellite swarms or fractionated spacecraft have experienced a very significant growth in the last decade. Migration from monolithic satellite architectures to new mission architectures involving large constellations of collaborative spacecraft is enabled by several hardware technologies and the application of modularity-driven designs, and presents numerous benefits such as low development costs and times and high flexibility. This has forced the exploration of new techniques and designs which have been often tackled from the hardware perspective but scarcely approached from the software architecture standpoint. This paper presents an autonomous software architecture and a management policy targeted for the broad range of distributed architecture missions. The paper presents the Local-Global approach, an adaptive management policy based on the collaboration between two levels of control which is aimed at enabling distributed mission control in dynamic and changing environments with limited computational capabilities. The Local- Global policy establishes the behaviouralmodel of a systemcomposed of a master scheduler and an arbitrary number of local schedulers, and describes the parameters that can be adjusted to reduce the amount of information processed by the master node which makes it suitable for different distributed spacecraft architectures.
    No preview · Article · Jun 2015
  • [Show abstract] [Hide abstract] ABSTRACT: Fractionated Satellite Networks are a popular concept in space systems. On these networks, several satellites cooperate and collaborate by exchanging resources wirelessly in order to obtain an aggregated network capability higher than the sum of the individual capabilities of the different satellites that compose it. Fractionated Satellite Networks are a generalization of Fractionated Satellites. Scalability is defined as the ability of a system to maintain its performance and function, and retain all its desired properties when its scale is increased greatly without having a corresponding increase in the systems complexity. The whole concept of fractionation (both at spacecraft level and network level) is based on the use of multiple satellites that jointly perform a function that can be further expanded by adding new satellites to the system. Because of this expandable nature of Fractionated Satellite Networks, the concept of scalability is critical on these architectures, as systems that do not scale well present a very poor performance when adding new agents, increasing costs and harming quality of service and stakeholder satisfaction. This paper presents a model and a framework for analyzing scalability of fractionated networks. Our model includes descriptions of the system at the resource, satellite, network and mission level. Connections and resource transfer among nodes are modelled using graphs whereas the study is approached from a resource allocation problem perspective. Finally, the utility and applications of the developed methodology is demonstrated through the analysis of a case study of a potential fractionated network.
    No preview · Article · Jun 2015 · IEEE Aerospace Conference Proceedings
  • [Show abstract] [Hide abstract] ABSTRACT: Graphene is enabling a plethora of applications in a wide range of fields due to its unique electrical, mechanical, and optical properties. Among them, graphene-based plasmonic miniaturized antennas (or shortly named, graphennas) are garnering growing interest in the field of communications. In light of their reduced size, in the micrometric range, and an expected radiation frequency of a few terahertz, graphennas offer means for the implementation of ultra-short-range wireless communications. Motivated by their high radiation frequency and potentially wideband nature, this paper presents a methodology for the time-domain characterization and evaluation of graphennas. The proposed framework is highly vertical, as it aims to build a bridge between technological aspects, antenna design, and communications. Using this approach, qualitative and quantitative analyses of a particular case of graphenna are carried out as a function of two critical design parameters, namely, chemical potential and carrier mobility. The results are then compared to the performance of equivalent metallic antennas. Finally, the suitability of graphennas for ultra-short-range communications is briefly discussed.
    No preview · Article · Apr 2015 · IEEE Transactions on Communications
  • [Show abstract] [Hide abstract] ABSTRACT: This article presents a low quiescent current output-capacitorless quasi-digital complementary metal-oxide-semiconductor (CMOS) low-dropout (LDO) voltage regulator with controlled pass transistors according to load demands. The pass transistor of the LDO is segmented into two smaller sizes based on a proposed segmentation criterion, which considers the maximum output voltage transient variations due to the load transient to different load current steps to find the suitable current boundary for segmentation. This criterion shows that low load conditions will cause more output variations and settling time if the pass transistor is used in its maximum size. Furthermore, this situation is the worst case for stability requirements of the LDO. Therefore, using one smaller transistor for low load currents and another one larger for higher currents, a proper trade-off between output variations, complexity, and power dissipation is achieved. The proposed LDO regulator has been designed and post-simulated in HSPICE in a 0.18 µm CMOS process to supply a stable load current between 0 and 100 mA with a 40 pF on-chip output capacitor, while consuming 4.8 μA quiescent current. The dropout voltage of the LDO is set to 200 mV for 1.8 V input voltage. The results reveal an improvement of approximately 53% and 25% on the output voltage variations and settling time, respectively. Copyright © 2015 John Wiley & Sons, Ltd.
    No preview · Article · Apr 2015 · International Journal of Circuit Theory and Applications
  • No preview · Conference Paper · Mar 2015
  • [Show abstract] [Hide abstract] ABSTRACT: Multicast on-chip communications are expected to become an important concern as the number of cores grows and we reach the manycore era. The increasing importance such traffic flows directly contrasts with the diminishing multicast performance of current Network-on-Chip (NoC) designs, and has lead to a surge of research works that seek to improve on-chip multicast support. Within this context, one-to-many traffic models may become useful for the early-stage design and evaluation of these proposals. However, existing models do not distinguish between unicast and multicast flows and often do not consider different multiprocessor sizes. To bridge this gap, a multicast scalability analysis is presented, aiming to provide tools for the modeling of multicast communications for NoC design and evaluation purposes.
    No preview · Article · Jan 2015
  • [Show abstract] [Hide abstract] ABSTRACT: Graphene is enabling a plethora of applications in a wide range of fields due to its unique electrical, mechanical, and optical properties. In this context, graphene antennas are envisioned to enable ultra-high-speed wireless communication in short transmission ranges, due to both their reduced size and their radiation frequency in the terahertz band. Despite its high potential bandwidth, the terahertz band presents several phenomena that may impair the communication and reduce the achievable data rate. In this letter, the phenomenon of molecular absorption is quantitatively analyzed, evaluating the scalability of both time- and frequency-domain performance metrics with the transmission distance. The results of this analysis show that molecular absorption creates a tradeoff between the achievable throughput and the maximum transmission distance at which short-range terahertz wireless communications can successfully take place.
    No preview · Article · Jan 2015 · IEEE Antennas and Wireless Propagation Letters
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    [Show abstract] [Hide abstract] ABSTRACT: Graphene is a promising material which has been proposed to build graphene plasmonic miniaturized antennas, or graphennas, which show excellent conditions for the propagation of Surface Plasmon Polariton (SPP) waves in the terahertz band. Due to their small size of just a few micrometers, graphennas allow the implementation of wireless communications among nanosystems, leading to a novel paradigm known as Graphene-enabled Wireless Communications (GWC). In this paper, an analytical framework is developed to evaluate how the channel capacity of a GWC system scales as its dimensions shrink. In particular, we study how the unique propagation of SPP waves in graphennas will impact the channel capacity. Next, we further compare these results with respect to the case when metallic antennas are used, in which these plasmonic effects do not appear. In addition, asymptotic expressions for the channel capacity are derived in the limit when the system dimensions tend to zero. In this scenario, necessary conditions to ensure the feasibility of GWC networks are found. Finally, using these conditions, new guidelines are derived to explore the scalability of various parameters, such as transmission range and transmitted power. These results may be helpful for designers of future GWC systems and networks.
    Full-text · Article · Jan 2015 · IEEE Transactions on Communications

Publication Stats

2k Citations
124.93 Total Impact Points

Institutions

  • 1996-2014
    • Polytechnic University of Catalonia
      • • Department of Electrical Engineering (DEE)
      • • Department of Electronic Engineering (EEL)
      Barcino, Catalonia, Spain
    • Universitat Oberta de Catalunya
      • Electronic Engineering Department
      Barcino, Catalonia, Spain
  • 2012
    • KTH Royal Institute of Technology
      • School of Information and Communication Technology (ICT)
      Tukholma, Stockholm, Sweden
    • Bergische Universität Wuppertal
      • Faculty of Electrical, Media and Information Engineering
      Wuppertal, North Rhine-Westphalia, Germany
  • 2005-2008
    • University of Colorado at Boulder
      • Department of Electrical, Computer, and Energy Engineering (ECEE)
      Boulder, Colorado, United States
  • 2006
    • Escuela Universitaria de Ingeniería Técnica Industrial de Bilbao
      Bilbo, Basque Country, Spain
  • 1998-2006
    • Universitat Rovira i Virgili
      • Department of Electronic, Electrical and Automatic Engineering (DEEEA)
      Tarraco, Catalonia, Spain