Analysis and Design Methodologies for Switched-Capacitor Filter Circuits in Advanced CMOS Technologies

Analog filters are an extremely important block in several electronic systems, such as RF transceivers, data acquisition channels, or sigma-delta modulators. They allow the suppression of unwanted frequencies bands in a signal, improving the system’s performance. These blocks are typically implemented using active RC filters, gm-C filters, or switched-capacitor (SC) filters. In modern deep-submicron CMOS technologies, the transistors intrinsic gain is small and has a large variability, making the design of moderate and high-gain amplifiers, used in the implementation of filter blocks, extremely difficult. To avoid this difficulty, in the case of SC filters, the opamp can be replaced with a voltage buffer or a low-gain amplifier (< 2), simplifying the amplifier’s design and making it easier to achieve higher bandwidths, for the same power. However, due to the loss of the virtual ground node, the circuit becomes sensitive to the effects of parasitic capacitances, which effect needs to be compensated during the design process. This thesis addresses the task of optimizing SC filters (mainly focused on implementations using low-gain amplifiers), helping designers with the complex task of designing high performance SC filters in advanced CMOS technologies. An efficient optimization methodology is introduced, based on hybrid cost functions (equation-based/simulation-based) and using genetic algorithms. The optimization software starts by using equations in the cost function to estimate the filter’s frequency response reducing computation time, when compared with the electrical simulation of the circuit’s impulse response. Using equations, the frequency response can be quickly computed (< 1 s), allowing the use of larger populations in the genetic algorithm (GA) to cover the entire design space. Once the specifications are met, the population size is reduced and the equation-based design is fine-tuned using the more computationally intensive, but more accurate, simulation-based cost function, allowing to accurately compensate the parasitic capacitances, which are harder to estimate using equations. With this hybrid approach, it is possible to obtain the final optimized design within a reasonable amount of computation time. Two methods are described for the estimation of the filter’s frequency response. The first method is hierarchical in nature where, in the first step, the frequency response is optimized using the circuit’s ideal transfer function. The following steps are used to optimize circuits, at transistor level, to replace the ideal blocks (amplifier and switches) used in the first step, while compensating the effects of the circuit’s parasitic capacitances in the ideal design. The second method uses a novel efficient numerical methodology to obtain the frequency response of SC filters, based on the circuit’s first-order differential equations. The methodology uses a non-hierarchical approach, where the non-ideal effects of the transistors (in the amplifier and in the switches) are taken into consideration, allowing the accurate computation of the frequency response, even in the case of incomplete settling in the SC branches. Several design and optimization examples are given to demonstrate the performance of the proposed methods. The prototypes of a second order programmable bandpass SC filter and a 50 Hz notch SC filter have been designed in UMC 130 nm CMOS technology and optimized using the proposed optimization software with a supply voltage of 0.9 V. The bandpass SC filter has a total power consumption of 249 uW. The filter’s central frequency can be tuned between 3.9 kHz and 7.1 kHz, the gain between -6.4 dB and 12.6 dB, and the quality factor between 0.9 and 6.9. Depending on the bit configuration, the circuit’s THD is between -54.7 dB and -61.7 dB. The 50 Hz notch SC filter has a total power consumption of 273 uW. The transient simulation of the circuit’s extracted view (C+CC) shows an attenuation of 52.3 dB in the 50 Hz interference and that the desired 5 kHz signal has a THD of -92.3 dB

Design of switched-capacitor filters using low gain amplifiers

Dissertação para obtenção do Grau de Mestre em Engenharia Electrotécnica e de ComputadoresAnalog filters are extremely important blocks in several electronic systems such as RF transceivers or sigma delta modulators. They allow selecting between signals with different frequency and eliminating unwanted signals. In modern deep-submicron CMOS technologies the intrinsic gain of the transistors is low and has a large variability, making the design of moderate and high gain amplifiers extremely difficult. The objective of this thesis is to study switched-capacitor (SC) circuits based on the low-pass and band-pass Sallen-Key topologies, since they do not require high gain amplifiers. The strategy used to achieve this objective is to replace the operational amplifier (opamp) with a voltage buffer. Doing this simplifies the design of the amplifier although it also eliminates the virtual ground node from the circuit. Without this node parasitic insensitive SC networks cannot be used. Due to modern parasitic extraction software that can reliably predict the values of parasitic capacitances, the historical disadvantage of parasitic sensitive SC networks (parallel SC) is no longer critical, allowing its influence to be compensated during the design process. Different types of switches were simulated to determine the one with the least nonlinear effects. Two techniques (common mode voltage adjustment and source degeneration) were used to reduce the distortion introduced by the buffers. Low-pass (second and sixth order) and band-pass (second and fourth order) SC filters were simulated in differential configuration in standard 130 nm CMOS technology, having obtained for the low-pass filter a distortion of -62 dB for the biquad section and -54 dB for the sixth-order filter, for a cutoff frequency of 1MHz and when operating at 100 MHz of clock frequency. The total power consumption was 986 W and 5.838 mW, respectively

Procedural Generation of 2D Games

Tese de mestrado, Engenharia Informática (Interação e Conhecimento) Universidade de Lisboa, Faculdade de Ciências, 2020The main objective of this project is to develop a procedural generator of levels for 2D games, with the capacity of adapting the difficulty of the levels to a player’s skill in a specific game. Thus, in order to implement a procedural generator with the previously mentioned features, we intend to combine two techniques: procedural content generation and dynamic difficulty adjustment. Procedural content generation is a technique which has the purpose of creating content for a game. The game content generated can be anything related to the video-game in question (e.g. characters, items, terrain, levels). Dynamic difficulty adjustment is the name of the technique used to make adjustments to the game’s difficulty, depending on the overall progress of a player in a particular level. The procedural content generator developed uses the idea of rhythms of a level as its basis (Smith et al., 2009). This approach consists on describing a level as a sequence of actions that must be done to successfully conclude it. Our methodology differs from the classical rhythm-based approach, because instead of a sequence of single actions we rep resent a level as a sequence of classes of actions. A class of actions is a group of actions that have the same assumed difficulty, which is defined by a mechanic description (what keys to press to perform an action). For the generation of these sequences of classes of actions, it is used a genetic algorithm whose fitness function is able to evaluate the difficulty of a sequence, which allows it to generate rhythms for diverse levels with different difficulties. After the rhythm generation process, the resulting sequences of classes of actions are going to be passed as a parameters to a geometry generator, that is going to associate each of the class of actions to a level chunk, having, in the end, a new playable level (a group of level chunks). This approach was then tested with different games to demonstrate the generator’s capacity to generalize and, to prove our definitions of difficulty, we made some tests using search algorithms and human players to make this evaluation

Semilinear fractional differential equations: global solutions, critical nonlinearities and comparison results

In this work we study several questions concerning to abstract fractional Cauchy problems of order α ∈ (0, 1). Concretely, we analyze the existence of local mild solutions for the problem, and its possible continuation to a maximal interval of existence. The case of critical nonlinearities and corresponding regular mild solutions is also studied. Finally, by establishing some general comparison results, we apply them to conclude the global well-posedness of a fractional partial differential equation coming from heat conduction theory.Conselho Nacional de Desenvolvimento Científico e TecnológicoCoordenação de aperfeiçoamento de pessoal de nivel superiorFundação de Amparo à Pesquisa do Estado de São PauloMinisterio de EducaciónMinisterio de Ciencia e InnovaciónJunta de Andalucí

Energy planning for Bahia in 2050: scenarios and discussion related to renewable energy for eletricity generation

Energy planning is strategic and fundamental for any country or region that aims to ensure development and prosperity for its people. The Brazilian Electric Matrix needs to expand and diversify to ensure national energy security and simultaneously maintain its predominance in renewable sources. This is possible only through a coherent energy planning and appropriate public policies. This work is an exploratory research about the electricity sector in the State of Bahia and in the rest of Brazil. It aims to assess electricity supply/demand scenarios for 2050, focusing on the potential growth of concentrated generation based on wind, solar photovoltaic and biomass renewable sources in Bahia while considering sustainability issues. This study was based on the National Plans (PNEs), prepared by the Empresa de Pesquisa Energética – EPE (Energy Research Company), as well as on other technical documents that guide the Brazilian energy planning. Three national demand scenarios were proposed, being two among them based in pre-existing PNEs scenarios while the last one is a projection of the original scenario. Three supply scenarios were also designed for Bahia, based on the potential growth of the new renewable sources mentioned above. Finally, there was a data crossing between national demand scenarios and supply scenarios for Bahia, producing nine possible general scenarios. As results, eight general scenarios point to Bahia as a future net exporter of renewable energy against one single scenario pointing Bahia as a future net importer of electricity. Bahia can have socioeconomic gains with investments, the creation/maintenance of jobs, environmental benefits with reduction of GHG emissions; besides water savings liters for CHESF´s hydroelectric reservoirs.O planejamento energético é estratégico e fundamental para qualquer país ou região que visa garantir o desenvolvimento e a prosperidade de seu povo. A Matriz Elétrica Brasileira precisa se expandir e diversificar para garantir a segurança energética nacional e simultaneamente manter sua predominância em fontes renováveis. Isso só é possível por meio de um planejamento energético coerente e de políticas públicas adequadas. Este trabalho é uma pesquisa exploratória sobre o setor elétrico no Estado da Bahia e no restante do Brasil. O objetivo é avaliar os cenários de oferta/demanda de energia elétrica para 2050, com foco no potencial de crescimento da geração concentrada baseada em fontes eólica, solar fotovoltaica e biomassa renovável na Bahia, considerando questões de sustentabilidade. Este estudo foi baseado nos Planos Nacionais de Energia (PNEs), elaborados pela Empresa de Pesquisa Energética – EPE, bem como em outros documentos técnicos que orientam o planejamento energético brasileiro. Foram propostos três cenários de demanda nacional, sendo dois deles baseados em cenários dos PNEs pré-existentes e o último é uma projeção do cenário original. Também foram projetados três cenários de abastecimento para a Bahia, com base no potencial de crescimento das novas fontes renováveis citadas acima. Por fim, realizou-se um cruzamento de dados entre cenários de demanda nacional e cenários de oferta para a Bahia, produzindo nove cenários gerais possíveis. Como resultados, oito cenários gerais apontam a Bahia como futuro exportador líquido de energia renovável contra um único cenário que aponta a Bahia como futuro importador líquido de energia elétrica. A Bahia pode ter ganhos socioeconômicos com investimentos, geração/manutenção de empregos, benefícios ambientais com redução de emissões de GEE; além da economia de litros de água para os reservatórios das usinas hidrelétricas da CHESF

Escala de Capital Cultural: Evidências de validade baseadas na estrutura interna

This study aims to validate the Cultural Capital in Family Interactions Scale through validity evidence, focusing on the internal structure of the instrument. As outlined by the Bourdiesian theory, cultural capital is considered a set of cultural and social assets acquired in the domestic environment, and its direct relationship with students' academic performance is highlighted. In this analysis, we used a sample of 11,795 5th-grade students who answered a questionnaire. Data collection was done electronically. The Parallel Analysis indicated two factors: Static Cultural Capital and Relational Cultural Capital, with Guttman's lambda 2 assuming values of 0.702 and 0.845, respectively. We calculated UniCO = 0.787, ECV = 0.669 and MIREAL = 0.318 indices. We used Exploratory Factor Analysis and Partial Confirmatory Factor Analysis. The adjustment indices CFI = 0.946 and TLI = 0.935, and the residue index RMSEA = 0.053, the analysis of internal consistency, determinants, and replicability of the factorial scores gave us evidence of validity for the use of the Cultural Capital Scale in Family Interactions.Este estudio tiene como objetivo validar la Escala de Capital Cultural en Interacciones Familiares a través de evidencia de validez, centrándose en la estructura interna del instrumento. El capital cultural, tal como lo plantea la teoría bourdiesiana, es considerado un conjunto de bienes culturales y sociales adquiridos en el entorno doméstico, y se destaca su relación directa con el rendimiento académico de los estudiantes. En este análisis, utilizamos una muestra de 11.795 estudiantes de 5º grado que respondieron un cuestionario. La recolección de datos se realizó electrónicamente. El Análisis Paralelo indicó dos factores: Capital Cultural Estático y Capital Cultural Relacional, con la lambda 2 de Guttman asumiendo valores de 0,702 y 0,845, respectivamente. Calculamos los índices UniCO = 0,787, ECV = 0,669 y MIREAL = 0,318. Utilizamos Análisis Factorial Exploratorio y Análisis Factorial Confirmatorio Parcial. Los índices de ajuste CFI = 0,946 y TLI = 0,935, y el índice de residuos RMSEA = 0,053, los análisis de consistencia interna, determinación y replicabilidad de las puntuaciones factoriales nos dieron evidencia de validez para el uso de la Escala de Capital Cultural en las Interacciones Familiares.Este estudo visa validar a Escala de Capital Cultural nas Interações Familiares por meio de evidências de validade, centrando-se na estrutura interna do instrumento desenvolvido pelos autores. O capital cultural, conforme delineado pela teoria bourdiesiana, é considerado um conjunto de ativos culturais e sociais adquiridos no ambiente doméstico, e sua relação direta com o desempenho escolar dos alunos é destacada. Nessa análise, foi utilizado uma amostra de 11.795 alunos do 5° ano que responderam a um questionário. A coleta dos dados foi feita de forma eletrônica. A Análise Paralela indicou dois fatores: Capital Cultural Estático e Capital Cultural Relacional, com lambda 2 de Guttmam assumindo os valores de 0,702 e 0,845, respectivamente. Calcularam-se os índices UniCO = 0,787, ECV = 0,669 e MIREAL = 0,318. Foi realizado uma Análise Fatorial Exploratória e Análise Fatorial Confirmatória Parcial. Os índices de ajustes CFI = 0,946 e TLI = 0,935, e o índice de resíduo RMSEA = 0,053, as análises de consistência interna, de determinância e replicabilidade dos escores fatoriais nos indicaram evidências de validade para a utilização da Escala de Capital Cultural nas Interações Familiares

Factor graphs and iterative decoding : new developments

Orientador: Jaime PortugheisTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de ComputaçãoResumo: Esta tese aborda métodos de estimação probabilística em sistemas de comunicações usando a teoria de grafos-fatores e seu algoritmo genérico soma-produto. Estas ferramentas são atualmente reconhecidas como um ambiente ideal para derivar vários esquemas de decodificação/ estimação, e também integrar modelos de componentes típicos num sistema de comunicação para melhor desempenho do processo de recepção. Mais genericamente, são adequadas para projetos de receptores unificados. Além disso, vários esquemas de decodificação conjunta fonte/canal podem ser contextualizados neste ambiente. Partimos de uma revisão geral da teoria grafos-fatores e do algoritmo soma-produto de forma abrangente e inserindo os fundamentos matemáticos relacionados. Na sequência aplicamos estes conceitos a sistemas de comunicações. Focamos em sistemas de grafos com ciclos, que são de grande interesse e que resultam na versão iterativa do algoritmo somaproduto, onde cronogramas de execução devem ser arbitrados eficientemente. Descrevemos a decodificação turbo seguindo esquemas de grafos-fatores normais e causais, a forma mais apropriada para a descrição e análise de cronogramas. A partir desta formulação, estudamos o caso da decodificação turbo na sua variante não-bloco, com entrelaçadores periódicos e decodificação contínua/causal. Apresentamos um cronograma completo do algoritmo soma-produto para este caso, mostrando vantagens práticas em relação ao proposto na literatura, sobretudo em relação a sua implementação. Na última parte da tese, apresentamos um estudo da aplicação de grafos-fatores no problema de decodificação iterativa conjunta fonte/canal. Partimos de um modelo genérico de fonte com memória, discreta no tempo e contínua em amplitude, consideramos quantização vetorial e tratamos o problema da decodificação iterativa conjunta integrando modelos destes componentes com o resto do sistema. Alguns resultados de simulações computacionais para os esquemas propostos são apresentadosAbstract: The present thesis deals with probabilistic inference methods for communication systems described by the unifying framework of factor graphs and the general elimination algorithm, the so called sum-product algorithm. These exceedingly general tools are understood as a state of the art environment to build many decoding schemes, and to model typical components for a joint efficient inference at reception. More generally, is a suitable framework to unified receiver designs. Additionally, some joint source channel decoding schemes can also be proper modeled under this context. We start with a review of this framework and related mathematical topics. Thereafter, we particularize to cases of interest, like typical communication systems. This framework gives powerful insights into the structures of multivariate constrained systems and shows how distributed probabilistic inferences can be performed, as shown for typical communication systems with a standard channel encoder. Systems represented by fator graphs with cycles are the most relevant. For the iterative version of the sum-product algorithm, a calculation schedule has to be efficiently chosen. We review the turbo decoding scheme for the classical turbo code using a normal and causal factor graph realization, providing an environment for scheduling descriptions. Then, we approach the non-block turbo decoding version (stream-oriented turbo codes), where general periodic and causal interleavers can be used and continuous decoding schemes are required. We present a full decoding sum-product schedule for this case, with pratical improvements over the usual non-graphical decoding scheme. In the last part of this thesis, we address the joint source channel decoding problem using the factor-graph framework. Starting from a general source model, linear discrete time series, we consider straight vectorial quantization. Instead of trying to remove redundancy, we go in the direction of building decoding schemes that explore this redundancy from source model and quantizer map.We analyse cases when iterative decoding can be performed taking these elements into account in a proper way. Some simulation on the proposed schemes are presentedDoutoradoTelecomunicações e TelemáticaDoutor em Engenharia Elétric

O papel das PCHS na economia catarinense

TCC (graduação) - Universidade Federal de Santa Catarina. Centro Sócio-Econômico. Economia.Em relação ás plantas industriais geradoras de energia elétrica, as PCHs são de significativa importância para o enriquecimento da matriz de energia elétrica do Brasil e também do estado de Santa Catarina. Pois são empreendimentos bem integrados ao desenvolvimento sustentável, causam poucos impactos negativos para o ambiente e também para a sociedade de um modo geral. Atualmente as PCHs são responsáveis por 2,9% da energia elétrica gerada no Brasil, no estado de Santa Catarina as PCHs representam 4,67% da capacidade. Esta parcela na geração de energia elétrica ira aumentar significativamente no futuro devido ao grande número de projetos em execução (construção e outorgados pela ANEEL). Atualmente as PCHs são empreendimentos muito procurados por investidores de todos os portes, e também são muito visados pelas empresas estatais que atuam na área de energia elétrica, pois as PCHs possuem um grande pacote de incentivos que as tornam um investimento muito lucrativo

Cálculo de Malliavin e análise no espaço de Wiener

Orientador: Paulo Regis Caron RuffinoDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Matematica, Estatistica e Computação CientificaResumo: A presente monografia contém um estudo de aspectos fundamentais da análise no espaço de Wiener. Os tópicos abordados são: a decomposição em Caos de Wiener, Integrais Múltiplas de Wiener, Derivada de Malliavin e Integral de Skorohod. Também são apresentadas as principais relações destes com a Integral de Itô e algumas aplicações ao cálculo antecipativo.Abstract: This monograph contains a study on the fundamentaIs aspects of analysis in the Wiener space. Subjects are: Wiener chaos decomposition, Multiple Wiener integraIs, Malliavin derivative and Skorohod integral. We also present the relations between this elements and Ito integral. Some aplications of this tools to antecipative stochastic calculus are showed.MestradoMestre em Matemátic

The effects of climate change on the distribution of South American antbirds (Thamnophilus punctatus complex) as affected by niche divergences and contact zone interactions between species

Several studies have shown that climatic change has been accelerating due to human activities, leading to dramatic effects on biodiversity. Modeling studies describe how species have reacted in the past to climatic change, and this information can help us to understand the degree of biotic susceptibility to current and future climatic change. This work aims to determine the effects of past, current and future climatic changes on the geographic distribution of the species complex Thamnophilus punctatus, a bird clade widely distributed across Neotropical dry forests. We also investigate if species that are phylogenetically similar have comparable climatic niches and, consequently, can be expected to respond similarly to climatic change. For this purpose, we calculated similarity, niche overlap, equivalence and genetic distance between all species, modeling their geographic distributions during the Last Glacial Maximum (LGM) as well as under current conditions and future (2050-2080) scenarios. Our results indicate that there are differences in responses to climatic changes from the LGM to the present among the five species of the T. punctatus complex and that the niches in the measured dimensions are not conserved among the studied species. We therefore suggest that the adequate environmental space of taxa of a widely distributed lineage can be shaped in distinct way, regardless of how closely related their species are or how much their niches overlap. Competitive exclusion in zones of contact is an important factor determining the geographical range of the species of the Thamnophilus punctatus complex, particularly for the very closely related species T. sticturus, T. pelzelni and T. ambiguus.Peer reviewe