Papers by Luiz Carlos Kretly
Anais do XXI Simpósio Brasileiro de Telecomunicações
The PIFA, Planar Inverted-F Antenna, is a type of antenna which has been used in many communicati... more The PIFA, Planar Inverted-F Antenna, is a type of antenna which has been used in many communication applications. It is a medium bandwidth radiator with reduced dimensions. A PIFA antenna on an EBG, Electromagnetic Band-Gap, structure is designed and measured, and is compared to a classical PIFA antenna. EBG structures have special electromagnetic properties that are very useful for wireless applications. The EBG structure presented in this paper is the AMC, Artificial Magnetic Conductor, also called mushroom-like electromagnetic band-gap structure. It is a metal-dielectric structure which presents high surface impedance and suppression of propagating surface currents within a frequency band. The AMC is used as the PIFA antenna ground plane to observe the improvement on characteristics such as bandwidth, gain and directivity. A PIFA antenna array is also presented on an AMC structure. The wide bandwidth achieved by the antenna array on AMC is shown. It is also shown that array radiation pattern is steerable in the azimuth plane. Besides, using the AMC, the overall antenna characteristics are improved.
2022 9th International Conference on Electrical and Electronics Engineering (ICEEE)
2021 IEEE International Conference on Microwaves, Antennas, Communications and Electronic Systems (COMCAS), 2021
This work presents a derivation of the Newton-Raphson method, treated here as the Quasi-Newtonian... more This work presents a derivation of the Newton-Raphson method, treated here as the Quasi-Newtonian (QN) algorithm. The QN has the same proprieties as the traditional Newton-Raphson method for extreme seeking, but due to a different manipulation of the Taylor series expansion, the method becomes a second-order method instead of a first-order method. Hence acquiring a fast convergence. That characteristic is explored in the performance of the Perturb and Observe algorithm for maximum power point tracking of photovoltaic systems. At this work, the QN is used not only to analyze the slope of the PxV curve of the photovoltaic system in order to choose the perturbation direction inserted by the Perturb and Observe algorithm (P&O) but to calculate the value of the perturbation as well. The simulation results have shown a fast-tracking of the maximum power point (MPP) and a small steady-state error when compared to the classical P&O algorithm.
2018 IEEE-APS Topical Conference on Antennas and Propagation in Wireless Communications (APWC), 2018
The aim of this work is to identify through time domain reflectometry –TDR, the electronics signa... more The aim of this work is to identify through time domain reflectometry –TDR, the electronics signature of Ribbon busbar connections versus the Wire busbar connections in polycrystalline solar cells. Nowadays it is common in the PV market the use of ribbon busbar in lamination process instead the use wire busbar in lamination process, the wire busbar idea is to decrease effective shading compared to the rectangular shape of the ribbon busbar. Besides that, the wire techonology could employs different materials such as cooper. The TDR simulations here presented, could be a very powerful tool to identify the signature of the overall grid connections in different solar cells technologies, bulk materials for R & D and manufacturing purposes.
2014 IEEE Brasil RFID, 2014
In this work, a metamaterial-based antenna is designed to operate at 2.5 GHz for RFID application... more In this work, a metamaterial-based antenna is designed to operate at 2.5 GHz for RFID applications. The proposed device is composed by a circular antenna surrounded by fractal metamaterial structures placed at strategic positions, improving bandwidth and enhancing the antenna attunement at a desired frequency. The obtained results show that the use of the proposed antenna in RFID systems is very promising.
Anais do 2002 International Telecommunications Symposium
With the exponential development of wireless communication and miniaturization of RF transceivers... more With the exponential development of wireless communication and miniaturization of RF transceivers, the need for small and low profile antennas has been growing. Besides that, the Third Generation wireless communication system, 3G, will be more focused and driven largely by advances in the antennas array performance. The PIFA, Planar inverted-F antenna, has been recognized as a most promising candidate to satisfy these new requirements. This work describes a triangle PIFA antenna array, that was designed and optimized at 1.9GHz, by the simulation software ZELAND IE3D. Its radiation pattern is steerable, then it can be adapted and updated in accordance with the environment.
2008 7th International Caribbean Conference on Devices, Circuits and Systems, 2008
This work describes the design and modeling of RF and ground pads as a GSG structure for on-wafer... more This work describes the design and modeling of RF and ground pads as a GSG structure for on-wafer measurements. An equivalent circuit is proposed take into account ESD protection and the parasitic elements of the structure. The problem of the impedance contact between the microprobe and the GSG structure is also reported, as well as, results of an application using
Este trabalho tem como escopo o projeto e implementacao de indutores ativos em tecnologia CMOS pa... more Este trabalho tem como escopo o projeto e implementacao de indutores ativos em tecnologia CMOS para operacao em sistemas de radio frequencia. A grande area demandada por indutores passivos integrados, bem como a sua baixa indutância e baixo fator de qualidade associados, apresentam-se como um dos maiores limitantes no projeto de circuitos integrados aplicados as comunicacoes. Como alternativa, indutores ativos integrados tem sido propostos. O uso de topologias de circuitos que emulam o efeito do indutor passivo convencional torna-se atraente ao passo que o grau de compactacao e seletividade podem ser obtidos. Quatro topologias distintas de indutores ativos integrados sao abordadas, bem como uma aplicacao pratica. Resultados de simulacao e de experimentos sao apresentados Abstract
Agenda da sustentabilidade no Brasil: Conhecimentos teóricos, metodológicos e empíricos, 2021
Esta pesquisa tem por objetivo a concepcao de novas topologias de circuitos integrados e suas car... more Esta pesquisa tem por objetivo a concepcao de novas topologias de circuitos integrados e suas caracterizacoes para operacao em sistemas de radio-recepcao. O projeto e a fabricacao de chaves de RF, LNAs, mixer e VCOs sao apresentados. A tecnica SMILE (Spatial MultIplexing ofLocal Elements) foi adotada devido as suas vantagens e funcionalidade para a otimizacao fisica de antenas inteligentes. Essa tecnica requer um chaveamento sequencial das antenas do arranjo e para tal foi desenvolvido um controle de chaveamento acionado por um VCO digital. A demultiplexacao analogica do sinal e implementada atraves de um OTA e chaves analogicas diferenciais. Assim, alem da introducao de novas topologias de circuitos integrados, este trabalho estabelece procedimentos de projeto e simulacao associados a validacao dos dispositivos fabricados. Palavras-chave: circuitos integrados, radio-recepcao, antenas inteligentes, SMILE Abstract
2018 IEEE 19th Latin-American Test Symposium (LATS), 2018
This work presents a novel method to test and verify the impact and failure mechanisms of the RF ... more This work presents a novel method to test and verify the impact and failure mechanisms of the RF interference injection on smart power integrated circuits, over of control loop circuits, checking the stability, gain and phase margin changes. The design and test algorithm is developed, as well as is proposed a robust design guide line. Theoretical analysis, simulation and test results from a silicon vehicle blocks implemented in 0.35um and 0.6um CMOS technology are presented and discussed.
The authors present a new approach using genetic algorithms, neural networks and nanorobotics con... more The authors present a new approach using genetic algorithms, neural networks and nanorobotics concepts applied to the problem of control design for nanoassembly automation and its application in medicine. As a practical approach to validate the proposed design, we have elaborated and simulated a virtual environment focused on control automation for nanorobotics teams that exhibit collective behavior. This collective behavior is a suitable way to perform a large range of tasks and positional assembly manipulation in a complex 3D workspace. We emphasize the application of such techniques as a feasible approach for the investigation of nanorobotics system design in nanomedicine. Theoretical and practical analyses of control modelling is one important aspect that will enable rapid development in the emerging field of nanotechnology.
Este trabalho apresenta dois topicos de pesquisa, o primeiro e referente ao projeto e desenvolvim... more Este trabalho apresenta dois topicos de pesquisa, o primeiro e referente ao projeto e desenvolvimento da tecnologia de fabricacao de Chaves MEMS (Micro Electro Mechanical System) de RF e o segundo e o projeto de circuitos integrados. No que se refere a chaves MEMS, descreve-se o processo e a metodologia para projeto de Chaves MEMS paralela sobre linha de transmissao coplanar (CPW). A estrutura e composta de uma ponte metalica suspensa em ambos os lados por dois postes metalicos conectados ao plano de terra. As chaves sao projetadas para uma baixa tensao de ativacao (16 V) e com larga banda de operacao em frequencia (400 MHz ? 4GHz) possibilitando seu uso na maioria dos padroes de sistemas de comunicacao. Tambem e descrita a metodologia do projeto auxiliado por simulacoes eletromecânicas e eletromagneticas e finalmente e apresentada a caracterizacao de 4 chaves construidas. Apos extensa pesquisa na literatura tecnico-cientifica, foi identificado que este e o primeiro trabalho no Bras...
Este trabalho apresenta a analise detalhada, simulacoes numericas completas e os procedimentos pa... more Este trabalho apresenta a analise detalhada, simulacoes numericas completas e os procedimentos para o projeto e a implementacao de uma câmara GTEM -GigaHertz Transverse Electromagnetic- para analise de pre-conformidade em circuitos e sistemas eletronicos. O sistema construido e capaz de realizar testes de EMC - Electromagnetic Compatibility, tanto de interferencia - EMI quanto de susceptibilidade - EMS, na faixa de frequencia de 500 MHz - 18 GHz. O projeto apresenta uma inovacao ao introduzir estruturas metamateriais na câmara tornando-a mais flexivel na determinacao da frequencia e niveis de RF e Microondas de teste. Os detalhes do projeto, simulacoes, a tecnologia de fabricacao e medidas de validacao da GTEM sao descritos neste trabalho Abstract
This work describes the full-custom design procedures for a decade-counter IC in GaAs DCFL (Direc... more This work describes the full-custom design procedures for a decade-counter IC in GaAs DCFL (DirectCoupled FET Logic) logic family, starting from proof of concept until final layout completion, including the gates sizing stage and the choice of a layout strategy. This DCFL counter circuit topology is entirely based upon the classical TTL 7490 structure, which was chosen because of its versatility, and all its functionality is retained: this IC operates either as a ripple, divide-by-N (N in the 2 to 10 range), or as a symmetric divide-by-10, counter. The most important trade-offs are weighted against each other. All the circuit configurations were simulated in the HSpice software, and results show excellent counter operation with clock rates up to 1 GHz. This project was envisaged mainly for educational purposes. The designed IC will be implemented in the HGaAs-III MESFET technology by Vitesse Semiconductor (USA), a GaAs ASIC foundry, via Brazilian multi-project-circuits (PMU/FAPESP) ...
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Papers by Luiz Carlos Kretly