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Book
, Focus on Swarm Intelligence Research and Applications, : Nova Science Publishers, 2017. AbstractWebsite

Swarm intelligence techniques are among the most talented and successful approaches that gained a lot of popularity over the past two decades. They are inspired by animal behavior (such as ants, termites and bees) and insect conduct (by swarm, herd, flock and shoal phenomena) in order to develop these techniques in terms of mimicking their problem/solution abilities. These techniques provide good approximate solutions in a reasonable time for solving hard and complex problems in many engineering fields. This book is intended for researchers, engineers and graduate students with interests in swarm intelligence algorithms and their applications. It discusses and describes the various swarm intelligence techniques as useful tools for solving practical problems, such as urban traffic optimization, electrical engineering problems and the design of integrated analog circuits.

Book Chapter
Pereira, P., H. Fino, M. Fakhfakh, F. Coito, and M. Ventim-Neves, "LC-VCO Design Challenges in the Nano-Era", Analog/RF and Mixed-Signal Circuit Systematic Design, vol. 233: Springer Berlin Heidelberg, pp. 363-379, 2013. Abstract

The progressive scaling of CMOS technology towards nanometre sizes has made the implementation of highly integrated systems for the wireless communication systems possible. Additionally, higher speed, lower power consumption and area reduction has been reached. Due to the high-density integration needs, as well as to low cost fabrication, RF applications, such as the LC-voltage controlled oscillator (LC-VCO), are usually implemented in CMOS technology. The complexity of designing LC-VCOs has lead to the development of several design methodologies. This chapter introduces an optimization based methodology for the design of LC-VCOs, where its efficiency is granted by the use of analytical models to characterize the active and passive elements’ behaviour.

Pereira, P., F. Passos, and H. M. Fino, "Optimization-Based Design of RF-VCOs with Tapered Inductors", Performance Optimization Techniques in Analog, Mixed-Signal, and Radio-Frequency Circuit Design, Hershey, PA, USA, IGI Global, pp. 134 - 157, 2015. Abstract

Voltage-Controlled Oscillators (VCOs) are widely used in wireless transceivers. Due to the stringent specifications regarding phase-noise, LC-VCOs are usually adopted. The need for maximizing phase-noise as well as minimizing the power consumption makes imperious the adoption of optimization-based design methodologies. For the optimization of the LC-VCO characteristics, special attention must be paid to the integrated inductor design, since its quality factor may have a strong influence in the LC-VCO phase-noise. Furthermore, designers must ensure that the higher limit of VCO operating frequency is sufficiently below the inductor resonant frequency. In this chapter, a study on the influence of the quality factor of the inductors on the LC-VCO overall behavior is presented. Then, optimization of integrated inductors by exploring the inductor geometric layout is presented. Finally, results obtained for the design of an LC-VCO in 130nm Technology using a previously optimized inductor are presented.

Sallem, A., and P. Pereira, "Sensitivity Analysis in the Optimization of Analog Active Filters by Applying the Richardson Extrapolation", Focus on Swarm Intelligence Research and Applications: Nova Science Publishers, pp. 247-275, 2017. Abstract

The key step of the analog active filter design is the optimal selection of component values due to manufactured series (E12, E24, E48, E96 and E192). In this paper, four simulation-based metaheuristics are applied to optimize four active filters using commercials available ICs as building blocks. The emphasis of this work is applying Richardson extrapolation-based sensitivity analysis in the optimization process of analog active filters. Indeed, Richardson extrapolation technique facilitates the calculation of the partial derivatives for the sensitivity using the simulation-based evaluation, without an explicit mathematical expression. Viability and benefits of the sensitivity analysis are highlighted. Monte Carlo analysis is performed in order to investigate robustness of the proposed sensitivity analysis of the active filters in case of component value variations due to specified tolerances of manufactured series.

Pereira, P., A. Sallem, M. Fakhfakh, M. H. Fino, and F. Coito, "A Technology-Aware Optimization of RF Integrated Inductors", Analog Circuits: Applications, Design and Performance: Nova Science Publishers, Inc., pp. 213-234, February, 2012. Abstract

This Chapter presents the optimal design of radio-frequency integrated spiral inductors. The basic idea is to generate an analytical model to characterize integrated inductors based on the double {\ensuremathπ}-model, and offer to the designer an approach to determine the inductor layout parameters. Particle Swarm Optimization technique is used to generate optimal values of parameters of the developed models. Viability of the proposed models is highlighted via comparison with ASITIC simulation results.

Coito, F., H. Fino, and P. Pereira, "Variability-Aware Optimization of RF Integrated Inductors in Nanometer-Scale Technologies", Integrated Circuits for Analog Signal Processing, New York, Springer-Verlag, pp. 271-287, 2013. Abstract

Progressive scaling of CMOS technology towards nanoscale regime enables the design of highly integrated systems for the wireless communications market. As technology continues to scale, the variability in process parameters may cause significant deviations in device behaviour. The complexity of designing spiral inductors has lead to the development of multi-objective optimization based design methodologies yielding the generation of Pareto-optimal surfaces. However, the variability of the process parameters is usually ignored, yielding the selection of ideally optimal solutions in detriment of quasi-optimal solutions that may prove to be better, should the robustness against process parameter variation be accounted for. We propose the generation of an extended Pareto front containing both optima and quasi-optima solutions. Finally information on the robustness to process parameter variations, is used for electing the best design solutions.The evaluation of the extended set of sub-optima solutions requires methods capable to find the set of local optima, since solutions that are close to each other in the performance index space may be very distant in the design parameter space.

Conference Paper
Pereira, P., H. Fino, F. Coito, and M. Ventim-Neves, "ADISI- An efficient tool for the automatic design of integrated spiral inductors", Proc. 16th IEEE Int. Conf. Electronics, Circuits, and Systems ICECS 2009, pp. 799–802, 2009. Abstract

This paper introduces a tool for the optimization of CMOS integrated spiral inductors. Its aim is to offer designers a first approach on designing inductors without the need for fabrication. The core of the tool is an optimization procedure where technology constraints on the inductor layout parameters are considered by applying user-defined discretization on the design variables. User-defined constraints between layout parameters may also be accounted for, as a way of taking into account design heuristics. For those cases where the device area is a major concern area minimization may be considered. On the other hand, if a major design goal is the inductor quality factor the tool may yield the layout parameters which maximize the quality factor. The trade-off between quality factor and device area is evaluated through the generation of a graphical representation of quality factor versus output diameter for a given inductance. For the sake of simplicity the pi-model has been used for characterising the inductor. The application was developed in Matlab and the optimization toolbox is used. The validity of the design results obtained is checked against circuit simulation with ASITIC.

Cardoso, T., P. Pereira, V. Fernaao Pires, and J. F. Martins, "Android-based m-learning remote system for mobile power quality assessment in large buildings with renewable energies", Power Engineering, Energy and Electrical Drives (POWERENG), 2015 IEEE 5th International Conference on, Riga, Latvia, pp. 431-434, May, 2015. Abstract

Power Quality is a generic term focusing on several issues, going from reliability to the quality of service provided by the energy supplier. It addresses limiting aspects such as harmonic distortion, flicker, sags, swells and transients... It is important for the students to understand the differences between the large amounts of events that fit into poor power quality category. Moreover it is important for them to analyze real time non-laboratory events. To provide this experience to the students this paper presents a remote m-learning experimental system where several types of poor power quality events can be tested. The developed system is based on a power quality analysis distributed network and can be remotely accessed from a remote computer or smart phones.

Mar, A., F. Monteiro, P. Pereira, and J. Martins, "An Application to Improve Smart Heritage City Experience", Advances in Digital Cultural Heritage, Cham, Springer International Publishing, pp. 89–103, 2018. Abstract

Nowadays technologies relate to so many aspects in our daily life that makes society eager for more and more ways of using it. To keep up with this new technological world, all economic sectors, from industry to services, are trying to adapt their products into this new reality. Presently, cultural heritage is already a field where the application of technology allows a static site to be converted into an intelligent environment, with detailed information about a specific monument or historical place, becoming more interesting, not only for local habitants, but also for tourists. This paper describes an application that allows tourists, managers and historical sites' habitants to experience a completely new way of discovering those places, offering a visit with detailed real-time information taking into account their personal interests. Tourists will have at their disposal a full set of optimized routes, combining their interests with their visiting time.

Pereira, P., M. H. Fino, and M. Ventim-Neves, "Automatic generation of RF integrated inductors analytical characterization", Symbolic and Numerical Methods, Modeling and Applications to Circuit Design (SM2ACD), 2010 XIth International Workshop on, pp. 1-4, oct., 2010. Abstract

This paper addresses the automatic generation of RF integrated inductors model. In this work the double p-model is used as a way of characterizing the inductor behaviour over a frequency range beyond the self-resonant value. For the evaluation of the model element values analytical expressions based on technology parameters as well as on the device geometric characteristics are used. The use of a technology-based methodology for the evaluation of the model parameters grants the adaptability of the models generated to any technology. The inductor analytical characterization is integrated into an optimization-based tool for the automatic design of RF integrated inductors. This tool uses a Genetic Algorithm (GA) optimization procedure, where user defined constraints on the design parameters are taken into account. Due to the design constraints nature and topology constraints, discrete variables optimization techniques are used.

Sallem, A., P. Pereira, and M. Fakhfakh, "Automatic sensitivity analysis tool for analog active filter", 2017 24th IEEE International Conference on Electronics, Circuits and Systems (ICECS), pp. 124-127, Dec, 2017. Abstract

In this paper we deal with analog active filter design using discrete components taking into consideration tolerance effects. Sensitivity analysis is performed to determine the most influential components in the considered circuit, thus relative higher precision is offered to those parameters. Further, an in-loop optimization technique is considered, thus actual IC models are handled. An application example is presented. HSpice simulation results, supported by Monte Carlo analysis, are given to highlight efficiency of the proposed selection technique.

Pereira, P., and M. H. Fino, "CMOS Delay and Power Estimation for Deep Submicrometer Technologies Using EKV Model", 10th International Workshop on Symbolic and Numerical Methods, Modeling and Applications to Circuit Design (SM2ACD 2008), pp. 253–257, 2008. Abstract

This paper presents an analytical model for CMOS delay and power estimation in deep sub micrometer technologies. In this paper the EKV transistor model is considered as a way of granting the accuracy of results in the characterization of deep submicron CMOS circuits. The analytical model proposed is valid for a ramp input signal, and takes into account all the operation regions of the transistor as well the influence of the gate-to-drain capacitance. For estimating the power consumption, a simple numerical integration process is applied to the current wave. An application example considering the use of the model for the evaluation of the delay and power consumption associated to a CMOS inverter is considered. The validity of the results obtained with the proposed model for a 1.2V TSMCN65 CMOS inverter is checked against those obtained through Hspice simulation.

Pereira, P., and M. H. Fino, "Delay Propagation of a CMOS Inverter Using the Nexp Transistor Model", XXII Conference on Design of Circuits and Integrated Systems, pp. 12–16, November, 2007. Abstract

This paper presents an analytical model for the delay propagation of a CMOS Invert circuit. In this paper the Nexp transistor model is considered as a way of granting the accuracy of results in the characterization of submicron CMOS circuits. The analytical model proposed is valid for a ramp input, and takes into account all the operation regions of the transistor and take into account the influence of the gate-to-drain capacitance. An application example considering the use of the model for the evaluation of the delay associated to the CMOS inverter is considered. The validity of the results obtained with analytical model of a 1.8V SMIC018 CMOS inverter is checked against Hspice simulation of the circuit.

Jorge, A., J. Guerreiro, P. Pereira, J. Martins, and L. Gomes, "Energy Consumption Monitoring System for Large Complexes", Doctoral Conference on Computing, Electrical and Industrial Systems, DoCEIS 2010, vol. 314, Costa de Caparica - Portugal, Springer Boston, pp. 419-426, 2010. Abstract

This paper describes the development of an open source system for monitoring and data acquisition of several energy analyzers. The developed system is based on a computer with Internet/Intranet connection by means of RS485 using Modbus RTU as communication protocol. The monitoring/metering system was developed for large building complexes and was validated in the Faculdade de Ciências e Tecnologia University campus. The system considers two distinct applications. The first one allows the user to verify, in real time, the energy consumption of any department in the complex, produce load diagrams, tables and print, email or save all available data. The second application keeps records of active/reactive energy consumption in order to verify the existence of some anomalous situation, and also monthly charge energy consumption to each corresponding department.

Pereira, P., M. Fino, F. Coito, and M. Ventim-Neves, "GADISI – Genetic Algorithms Applied to the Automatic Design of Integrated Spiral Inductors", Doctoral Conference on Computing, Electrical and Industrial Systems, DoCEIS 2010, vol. 314, Costa de Caparica - Portugal, Springer Boston, pp. 515-522, 2010. Abstract

This work introduces a tool for the optimization of CMOS integrated spiral inductors. The main objective of this tool is to offer designers a first approach for the determination of the inductor layout parameters. The core of the tool is a Genetic Algorithm (GA) optimization procedure where technology constraints on the inductor layout parameters are considered. Further constraints regarding inductor design heuristics are also accounted for. Since the layout parameters are inherently discrete due to technology and topology constraints, discrete variable optimization techniques are used. The Matlab GA toolbox is used and the modifications on the GA functions, yielding technology feasible solutions is presented. For the sake of efficiency and simplicity the pi-model is used for characterizing the inductor. The validity of the design results obtained with the tool, is checked against circuit simulation with ASITIC.

Pereira, P., H. Fino, and M. Ventim-Neves, "LC-VCO design methodology based on evolutionary algorithms", Synthesis, Modeling, Analysis and Simulation Methods and Applications to Circuit Design (SMACD), 2012 International Conference on, Seville - Spain, pp. 189 - 192, 2012/sept.. Abstract

In his paper the design of LC-VCOs is addressed. Due to the high-density integration needs as well as to low cost fabrication, RF applications are usually implemented in CMOS technology. However, this technology development brought up several issues such as the degradation of on-chip LC tank quality factor, yielding VCO's phase noise limitation. To overcome phase-noise limitations, optimization design methodologies are usually used. Since electromagnetic simulations are timely expensive, model based approaches are needed. In this work the characterization of the oscillator behaviour is guaranteed by a set of analytical models describing each circuit element performance. A set of working examples for UMC130 technology, aiming the VCO phase noise and power consumption optimization, is addressed. The results presented, spotlight the potential of the proposed design methodology, combined with a GA optimization procedure, for an accurate and timely efficient oscillator design. The accuracy of the results is checked against HSPICE/RF simulator.

Pereira, P., M. Kotti, H. Fino, and M. Fakhfakh, "Metaheuristic algorithms comparison for the LC - Voltage controlled oscillators optimal design", 5th International Conference on Modeling, Simulation and Applied Optimization (ICMSAO), Hammamet, Tunisia, pp. 1 - 6, 28-30 April 2013. Abstract

The goal of this paper is to present a comparison among three known metaheuristics: Genetic Algorithm (GA), Particle Swarm Optimization (PSO) and Simulated Annealing (SA). For the comparison, the design of an LC - Voltage Controlled Oscillator (LC-VCO) is considered, where the minimization of both VCO phase noise and power consumption is envisaged. The objective of this comparison is to find the algorithm yielding the best solution. The validity of the solution obtained with each metaheuristic algorithm is checked against HSPICE/RF simulation results. Robustness checks for each algorithm are presented at the end of this paper.

Kchaou, O. B., A. Sallem, P. Pereira, M. Fakhfakh, and M. H. Fino, "Multi-objective sensitivity-based optimization of analog circuits exploiting NSGA-II front ranking", Synthesis, Modeling, Analysis and Simulation Methods and Applications to Circuit Design (SMACD), 2015 International Conference on, Istanbul, Turkey, pp. 1-4, Sept, 2015. Abstract

This work deals with the multi-objective optimization of analog circuits by generating the Pareto front where elements are low sensitive to parameters' variations. NSGA-II is used for obtaining the non-dominated solutions. Richardson extrapolation technique is used for the in-loop optimization approach for computing partial derivatives and, thus, the solutions' sensitivity. NSGA-II Pareto fronts' intrinsic ranking is exploited for the generation of the new ‘low-sensitive’ Pareto front. The case of the optimal sizing of a CMOS voltage follower is considered to exemplify the proposed approach.

Sallem, A., P. Pereira, M. Fakhfakh, and H. Fino, "A Multi-objective Simulation Based Tool: Application to the Design of High Performance LC-VCOs", Technological Innovation for the Internet of Things, vol. 394, Portugal, Springer Berlin Heidelberg, pp. 459-468, 2013. Abstract

The continuing size reduction of electronic devices imposes design challenges to optimize the performances of modern electronic systems, such as: wireless services, telecom and mobile computing. Fortunately, those design challenges can be overcome thanks to the development of Electronic Design Automation (EDA) tools. In the analog, mixed signal and radio-frequency (AMS/RF) domains, circuit optimization tools have demonstrated their usefulness in addressing design problems taking into account downscaling technological aspects. Recent advances in EDA have shown that the simulation-based sizing technique is a very interesting solution to the ‘complex’ modelling task in the circuit design optimization problem. In this paper we propose a multi-objective simulation-based optimization tool. A CMOS LC-VCO circuit is presented to show the viability of this tool. The tool is used to generate the Pareto front linking two conflicting objectives, namely the VCO Phase Noise and Power Consumption. The accuracy of the results is checked against HSPICE/RF simulations.

Martins, J. F., P. Pereira, A. J. Pires, and V. F. Pires, "A new teaching tool to enhance power quality assessment", Industrial Electronics Society, IECON 2015 - 41st Annual Conference of the IEEE, Yokohama, Japan, IEEE-IES, pp. 004158-004162, 9-12 Nov., 2015. Abstract

The study and assessment of Power Quality issues is nowadays a very important subject, particularly regarding Cyber-physical and Industrial Agents based systems, which are extremely sensitive to Power Quality disturbances. Giving students or engineers practical experience in this field requires a large investment from teaching institutions. This paper presents a laboratory device that emulates Power Quality disturbances in order to provide the required experimental expertize in the subject. It addresses limiting aspects such as harmonic distortion, flicker, sags, swells and transients. The developed system presents a good opportunity for technicians, even without deep knowledge on the field of power quality, to learn basic principles and be able to identify Power Quality events. Since the system is based on real data, represents a valuable approach giving trainees practical knowledge on the field.

Pereira, P., H. Fino, F. Coito, and M. Ventim-Neves, "Optimization-Based Design of Nano-CMOS LC-VCOs", Doctoral Conference on Computing, Electrical and Industrial Systems, DoCEIS 2012, vol. 372, Costa de Caparica - Portugal, Springer Boston, pp. 453-464, 2012. Abstract

This paper introduces a variability-aware methodology for the design of LC-VCOs in Nano-CMOS technologies. The complexity of the design as well as the necessity for having an environment offering the possibility for exploring design trade-offs has led to the development of design methodologies based multi-objective optimization procedures yielding the generation of Pareto-optimal surfaces. The efficiency of the process is granted by using analytical models for both passive and active devices. Although physics-based analytical expressions have been proposed for the evaluation of the lumped elements, the variability of the process parameters is usually ignored due to the difficulty to formalize it into an optimization performance index. The usually adopted methodology of considering only optimum solutions for the Pareto surface, may lead to pruning quasi-optimal solutions that may prove to be better, should their sensitivity to process parameter variation be accounted for. In this work we propose starting by generating an extended Pareto surface where both optimum and quasi-optimum solutions are considered. Finally information on the sensitivity to process parameter variations, is used for electing the best design solution.

Cardoso, T., P. Pereira, V. Fernao Pires, and J. F. Martins, "Power quality and long life education", Industrial Electronics (ISIE), 2014 IEEE 23rd International Symposium on, Istanbul - Turkey, pp. 2224 - 2228, 2014/06. Abstract

This paper presents a remote laboratory linked with mobile devices for real data analysis on the field of power quality. A global system was developed from the power quality analyzer into the human machine interface devoted to the m-learning system. This m-learning system is intended to be used in a long life learning perspective. The developed remote laboratory is a good opportunity for people, even without deep knowledge on the field, to learn power quality principles in an applied way. Since the system is based on real data, is a good approach to give trainees practical knowledge on the field.

Pereira, P., F. Coito, and H. Fino, "PSO-Based Design of RF Integrated Inductor", Doctoral Conference on Computing, Electrical and Industrial Systems, DoCEIS 2012, vol. 372, Costa de Caparica - Portugal, Springer Boston, pp. 475-482, 2012. Abstract

This paper addresses an optimization-based approach for the design of RF integrated inductors. The methodology presented deals with the complexity of the design problem by formulating it as a multi-objective optimization. The multi-modal nature of the underlying functions combined with the need to be able to explore design trade-offs leads to the use of niching methods. This allows exploring not only the best trade-off solutions lying on the Pareto-optimum surface but also the quasi-optimum solutions that would be otherwise discarded. In this paper we take advantage of the niching properties of lbest PSO algorithm using ring topology to devise a simple optimizer able to find the local-optima. For the efficiency of the process analytical models are used for the passive/active devices. In spite the use of physics-based analytical expressions for the evaluation of the lumped elements, the variability of the process parameters is ignored in the optimization stage due to the significant computational burden it involves. Thus in the final stage both the Pareto-optimum solutions and the quasi-optimum solutions are evaluated with respect to the sensitivity to process parameter variations.

Pereira, P., H. Fino, and M. Ventim-Neves, "RF Varactor Design Based on Evolutionary Algorithms", Mixed Design of Integrated Circuits and Systems (MIXDES), 2012 Proceedings of the 19th International Conference, Warsaw, Poland, pp. 277 -282, may, 2012. Abstract

This paper introduces an optimization methodology for the design of RF varactors. The characterization of the varactor behaviour is supported by a set of equations based on technological parameters, granting the accuracy of the results, as well as the adaptability of the model to any technology. The varactor design is achieved through the implementation of a Genetic Algorithms (GA) optimization methodology, which is able to deal with continuous and/or discrete variables, making possible to suit both technological and layout constraints. A set of working examples for UMC130 technology are addressed. The results presented, spotlight the potential of varactor analytical model, combined with a GA optimization procedure, when integrated in optimization design tools. The accuracy of the results is checked against HSPICE simulator.

Marouani, H., A. Sallem, M. Chaoui, P. Pereira, and N. Masmoudi, "A Robustness Study of Metaheuristics to the Optimal Design of RF Integrated Inductors", 2018 15th International Multi-Conference on Systems, Signals Devices (SSD), pp. 1459-1464, March, 2018. Abstract

In this paper, three metaheuristics are investigated to optimize RF Integrated Inductors; namely Differential Evolution (DE) from the field of evolutionary computation, Gravitational Search Algorithm (GSA) based on the law of gravity and mass interactions and Particle Swarm Optimization (PSO) inspired by swarm behaviors in nature. A particular interest is given to the optimization of RF Integrated Inductors. Performances in terms of optimum quality and computing time of the metaheuristics are checked via three test functions and one application that consist of optimizing performances of characterize integrated inductors based on the double$π$-model.