Analysis and Design of a Transmitter for Wireless Communications in CMOS Technology

The number of wireless devices has grown tremendously over the last decade. Great technology improvements and novel transceiver architectures and circuits have enabled an astonishingly expanding set of radio-frequency applications. CMOS technology played a key role in enabling a large-scale diffusion of wireless devices due to its unique advantages in cost and integration. Novel digital-intensive transceivers have taken full advantage of CMOS technology scaling predicted by Moore's law. Die-shrinking has enabled ubiquitous diffusion of low-cost, small form factor and low power wireless devices. However, Radio Frequency (RF) Power Amplifiers (PA) transceiver functionality is historically implemented in a module which is separated from the CMOS core of the transceiver. The PA is traditionally dictating power and battery life of the transceiver, thus justifying its implementation in a tailored technology. By contrast, a fully integrated CMOS transceiver with no external PA would hugely benefit in terms of reduced area and system complexity. In this work, a fully integrated prototype of a Switched-Capacitor Power Amplifier (SCPA) has been implemented in a 28nm CMOS technology. The SCPA provides the functionalities of a PA and of a Radio-Frequency Digital-to-Analog Converter (RF-DAC) in a monolithic CMOS device. The switching output stage of the SCPA enables this circuital topology to reach high efficiencies and offers excellent power handling capabilities. In this work, the properties of the SCPA are analyzed in an extensive and detailed dissertation. Nowadays Wireless Communications operate in a very crowded spectrum, with strict coexistence requirements, thus demanding a strong linearity to the RF-DAC section of the SCPA. A great part of the work of designing a good SCPA is in fact designing a good RF-DAC. To enhance RF-DAC linearity, a precision of the timing of the elements up to the ps range is required. The use of a single core-supply voltage in the whole circuit including the CMOS inverter of the switching output stage enables the use of minimum size devices, improving accuracy and speed in the timing of the elements. The whole circuit operates therefore on low core-supply voltage. Throughout this work, a detailed analysis carefully describes the electromagnetic structures which maximize power and efficiency of low-voltage SCPAs. Due to layout issues subsequent to limited available voltages, however, there is a practical limitation in the maximum achievable power of low-voltage SCPAs. In this work, a Multi-Port Monolithic Power Combiner (PC) is introduced to overcome this limitation and further enhance total achieved system power. The PC sums the power of a collection of SCPAs to a single output, allowing higher output powers at a high efficiency. Benefits, drawbacks and design of SCPA PCs are discussed in this work. The implemented circuit features the combination of four differential SCPAs through a four-way monolithic PC and is simulated to obtain a maximum drain efficiency of 44% at a peak output power of 29dBm on 1.1V supply voltage. Extensive spectrum analysis offers full evaluation of system performances. After exploring state-of-the-art possibilities offered by an advanced 28nm CMOS technology, this work predicts through rigorous theoretical analysis the expected evolution of SCPA performances with the scaling of CMOS Technologies. The encouraging forecast further emphasizes the importance of SCPA circuits for the future of high-performance Wireless Communications

BOOK-TAX DIFFERENCES E SUA RELEVÂNCIA INFORMACIONAL NO MERCADO DE CAPITAIS NO BRASIL

Este artigo tem como objetivo avaliar se existe relação entre BTD (Book-Tax Differences) e resultados futuros das empresas. Foi proposto um modelo adaptado à realidade brasileira para testar se BTD contribui para previsibilidade dos resultados (lucros líquidos futuros) e retorno (ganho de capital com ações). Nesse sentido, com uma amostra de 130 empresas num período entre 2004 e 2009, verificou-se pelo modelo proposto, significância estatística da influência de BTD na estimativa dos lucros e no retorno com ações das companhias abertas brasileiras. Além disso, o modelo indicou a existência de relação linear entre a variável dependente e as variáveis independentes, indicativo que os parâmetros das variáveis podem ser considerados diferentes de zero e dentro do intervalo de confiança, ausência de autocorrelação e de multicolinearidade. Dessa forma, conclui-se sobre a existência de relevância informacional de Book-Tax Differences num contexto de parâmetro para estimativa de resultados e retorno com ações das companhias abertas brasileiras. Acrescente-se que, ao evidenciar a percepção do mercado diante das diferenças entre o lucro contábil e o lucro tributável, esta pesquisa oferta evidências relevantes para identificação da qualidade e persistência nos lucros, assim como parâmetros para avaliação de empresas, retorno futuro de ações, impactos na classificação de crédito e interpretação do lucro tributável como medida de desempenho das companhias.

Cannabis use and the development of psychosis or schizophrenia, analysis of current legislation and regional mapping: A systematic review

Introducción: la relación entre el consumo de cannabis y la aparición de síntomas psicóticos está suficientemente fundamentada. La legalización y/o despenalización del cannabis podría aumentar la frecuencia y la cantidad de su consumo entre sus usuarios. Objetivo: esta revisión sistemática pretende resumir los hallazgos de los estudios que investigaron el riesgo, la precocidad y la intensidad de la psicosis en los consumidores de cannabis, teniendo en cuenta el estado de legalización y/o despenalización del consumo de cannabis en diferentes países. Metodología: fueron incluidos artículos publicados hasta mayo de 2018, en lengua inglesa, portuguesa y española, todos extraídos de las bases de datos PubMed y SciELO, respetando los criterios de inclusión y exclusión. Resultados: se incluyeron 19 estudios de 18 países. La relación entre el consumo de cannabis y el inicio de síntomas psicóticos estuvo suficientemente fundamentada. Sin embargo, no hubo datos que respaldaran un aumento en el riesgo, la precocidad o la intensidad de la psicosis en los consumidores de cannabis de países con niveles más altos de legalización/despenalización del uso de cannabis hasta la fecha del presente estudio. Conclusión: el consumo de cannabis está asociado con el desarrollo de psicosis. Hasta el momento, no hay datos que indiquen un aumento en la precocidad, el riesgo o la intensidad de la psicosis en usuarios de cannabis, debido a la legalización o despenalización del uso de cannabis. Sin embargo, la ausencia de datos hasta la fecha no excluye estas posibilidades, ya que ninguno de los estudios analizados en esta revisión evaluó específicamente los efectos de las políticas de legalización/despenalización en esos resultados. Por ello, los estudios prospectivos centrados en los efectos de las políticas de legalización o despenalización deben llevarse a cabo en países como Canadá, España, los Estados Unidos de América (algunos estados), los Países Bajos y Uruguay.Introduction: The relationship between cannabis use and the onset of psychotic symptoms is sufficiently substantiated. The legalization and/or decriminalization of cannabis could increase the frequency and quantity of cannabis use among its users. Objective: This systematic review aims to summarize the findings of studies that investigated the risk, precocity and intensity of psychosis in cannabis users, taking into account the status of legalization and/or decriminalization of cannabis use in different countries. Methodology: Articles published up to May 2018 were included, in English, Portuguese and Spanish, all extracted from the PubMed and SciELO databases, respecting the inclusion and exclusion criteria. Results: 19 studies from 18 countries were included. The relationship of cannabis use and the onset of psychotic symptoms was sufficiently substantiated. However, there was no data that supported an increase in the risk, precocity or intensity of psychosis in cannabis users from countries with higher levels of legalization/decriminalization of cannabis use to the date of the present study. Conclusion: The use of cannabis is associated with the development of psychosis. So far, there is no data pointing to an increase in the precocity, risk or intensity of psychosis in cannabis users, due to the legalization or decriminalization of the use of cannabis. However, the absence of data to date does not exclude these possibilities, since none of the studies analyzed in this review specifically assessed the effects of legalization/decriminalization policies on those outcomes. Therefore, prospective studies focused on the effects of legalization or decriminalization policies should be conducted in countries such as Canada, Spain, the United States of America (some states), the Netherlands, and Uruguay

ATLANTIC-PRIMATES: a dataset of communities and occurrences of primates in the Atlantic Forests of South America

Primates play an important role in ecosystem functioning and offer critical insights into human evolution, biology, behavior, and emerging infectious diseases. There are 26 primate species in the Atlantic Forests of South America, 19 of them endemic. We compiled a dataset of 5,472 georeferenced locations of 26 native and 1 introduced primate species, as hybrids in the genera Callithrix and Alouatta. The dataset includes 700 primate communities, 8,121 single species occurrences and 714 estimates of primate population sizes, covering most natural forest types of the tropical and subtropical Atlantic Forest of Brazil, Paraguay and Argentina and some other biomes. On average, primate communities of the Atlantic Forest harbor 2 ± 1 species (range = 1–6). However, about 40% of primate communities contain only one species. Alouatta guariba (N = 2,188 records) and Sapajus nigritus (N = 1,127) were the species with the most records. Callicebus barbarabrownae (N = 35), Leontopithecus caissara (N = 38), and Sapajus libidinosus (N = 41) were the species with the least records. Recorded primate densities varied from 0.004 individuals/km 2 (Alouatta guariba at Fragmento do Bugre, Paraná, Brazil) to 400 individuals/km 2 (Alouatta caraya in Santiago, Rio Grande do Sul, Brazil). Our dataset reflects disparity between the numerous primate census conducted in the Atlantic Forest, in contrast to the scarcity of estimates of population sizes and densities. With these data, researchers can develop different macroecological and regional level studies, focusing on communities, populations, species co-occurrence and distribution patterns. Moreover, the data can also be used to assess the consequences of fragmentation, defaunation, and disease outbreaks on different ecological processes, such as trophic cascades, species invasion or extinction, and community dynamics. There are no copyright restrictions. Please cite this Data Paper when the data are used in publications. We also request that researchers and teachers inform us of how they are using the data. © 2018 by the The Authors. Ecology © 2018 The Ecological Society of Americ

Analysis and Design of a Transmitter for Wireless Communications in CMOS Technology

The number of wireless devices has grown tremendously over the last decade. Great technology improvements and novel transceiver architectures and circuits have enabled an astonishingly expanding set of radio-frequency applications. CMOS technology played a key role in enabling a large-scale diffusion of wireless devices due to its unique advantages in cost and integration. Novel digital-intensive transceivers have taken full advantage of CMOS technology scaling predicted by Moore's law. Die-shrinking has enabled ubiquitous diffusion of low-cost, small form factor and low power wireless devices. However, Radio Frequency (RF) Power Amplifiers (PA) transceiver functionality is historically implemented in a module which is separated from the CMOS core of the transceiver. The PA is traditionally dictating power and battery life of the transceiver, thus justifying its implementation in a tailored technology. By contrast, a fully integrated CMOS transceiver with no external PA would hugely benefit in terms of reduced area and system complexity. In this work, a fully integrated prototype of a Switched-Capacitor Power Amplifier (SCPA) has been implemented in a 28nm CMOS technology. The SCPA provides the functionalities of a PA and of a Radio-Frequency Digital-to-Analog Converter (RF-DAC) in a monolithic CMOS device. The switching output stage of the SCPA enables this circuital topology to reach high efficiencies and offers excellent power handling capabilities. In this work, the properties of the SCPA are analyzed in an extensive and detailed dissertation. Nowadays Wireless Communications operate in a very crowded spectrum, with strict coexistence requirements, thus demanding a strong linearity to the RF-DAC section of the SCPA. A great part of the work of designing a good SCPA is in fact designing a good RF-DAC. To enhance RF-DAC linearity, a precision of the timing of the elements up to the ps range is required. The use of a single core-supply voltage in the whole circuit including the CMOS inverter of the switching output stage enables the use of minimum size devices, improving accuracy and speed in the timing of the elements. The whole circuit operates therefore on low core-supply voltage. Throughout this work, a detailed analysis carefully describes the electromagnetic structures which maximize power and efficiency of low-voltage SCPAs. Due to layout issues subsequent to limited available voltages, however, there is a practical limitation in the maximum achievable power of low-voltage SCPAs. In this work, a Multi-Port Monolithic Power Combiner (PC) is introduced to overcome this limitation and further enhance total achieved system power. The PC sums the power of a collection of SCPAs to a single output, allowing higher output powers at a high efficiency. Benefits, drawbacks and design of SCPA PCs are discussed in this work. The implemented circuit features the combination of four differential SCPAs through a four-way monolithic PC and is simulated to obtain a maximum drain efficiency of 44% at a peak output power of 29dBm on 1.1V supply voltage. Extensive spectrum analysis offers full evaluation of system performances. After exploring state-of-the-art possibilities offered by an advanced 28nm CMOS technology, this work predicts through rigorous theoretical analysis the expected evolution of SCPA performances with the scaling of CMOS Technologies. The encouraging forecast further emphasizes the importance of SCPA circuits for the future of high-performance Wireless Communications.Il numero dei dispositivi senza fili è cresciuto esponenzialmente negli ultimi dieci anni. Grandi progressi tecnologici e nuove architetture di ricetrasmettitori hanno reso possibile un'impressionante insieme di applicazioni a radio-frequenza. La tecnologia CMOS ha giocato un ruolo centrale nel rendere possibile una diffusione in larga scala di dispositivi senza fili grazie ai suoi esclusivi vantaggi in termini di costo e integrazione. Nuovi ricetrasmettitori marcatamente digitali hanno preso pieno vantaggio dell'evoluzione tecnologica prevista dalla legge di Moore. La riduzione della dimensione degli integrati microelettronici ha permesso una diffusione capillare di dispositivi senza fili a basso costo, di ridotte dimensioni e dal basso consumo. D'altra parte, la funzionalità degli amplificatori di potenza (PA) per radio frequenza (RF) è storicamente implementata in un modulo che è separato dal nucleo CMOS del ricetrasmettitore. Il PA determina tradizionalmente la potenza e la durata della batteria del ricetrasmettitore, e per ciò è giustificata la sua implementazione in una tecnologia dedicata. All'opposto, un ricetrasmettitore CMOS pienamente integrato senza PA esterno beneficerebbe largamente in termini di riduzione di area e di complessità di sistema. In questo lavoro, un prototipo completamente integrato di Amplificatore di Potenza a Capacità Commutate (SCPA) è stato implementato in una tecnologia CMOS a 28nm. L'SCPA fornisce le funzionalità di un PA e di un Convertitore Digitale-Analogico in Radio Frequenza (RF-DAC) in un dispositivo CMOS monolitico. Lo stadio d'uscita commutato dell'SCPA rende questa topologia capace di raggiungere alte efficienze e offre un'eccellente capacità di generare potenza. In questo lavoro, le proprietà dell'SCPA sono analizzate in una discussione estensiva e dettagliata. Le comunicazioni senza fili di oggi operano in uno spettro molto affollato, con requisiti di coesistenza molto stretti, che quindi richiedono un'alta linearità alla sezione RF-DAC dell'SCPA. Una grande parte del lavoro di progetto di un SCPA è infatti progettare un buon RF-DAC. Per migliorare la linearità dell'RF-DAC, è richiesta una precisione della temporizzazione degli elementi fino all'ordine di grandezza dei ps. L'uso di una singola tensione di alimentazione, incluso l'invertitore CMOS dello stadio di uscita commutato, rende possibile l'uso di dispositivi di dimensione minima, migliorando l'accuratezza e la velocità della temporizzazione degli elementi. L'intero circuito opera quindi su una bassa tensione di alimentazione. Nel corso di questo lavoro, un'analisi dettagliata descrive con attenzione le strutture elettromagnetiche che massimizzano la potenza e l'efficienza degli SCPA a bassa tensione. A causa di problemi di maschere dovuti alle limitate tensioni disponibili, comunque, c'è una limitazione pratica nella massima potenza che un SCPA a bassa tensione può raggiungere. In questo lavoro, un Sommatore di Potenza Monolitico Multi-Porta (PC) è introdotto per superare questa limitazione e incrementare ulteriormente la potenza di sistema totale. Il PC somma la potenza di una collezione di SCPA in una singola uscita, rendendo possibili potenze più alte con un'alta efficienza. I benefici, i problemi e il progetto dei PC per SCPA sono discussi in questo lavoro. Il circuito progettato comprende la combinazione di quattro SCPA attraverso un Sommatore di Potenza (PC) monolitico ed è simulato ottenere un'efficienza massima di collettore del 44% con una potenza di picco di 29dBm da una tensione di alimentazione di 1.1V. Estensive analisi di spettro offrono una completa valutazione delle prestazioni di sistema. Dopo aver esplorato le prestazioni dello stato-dell'arte offerte da un'avanzata tecnologia CMOS a 28nm, questo lavoro predice attraverso un'analisi teorica rigorosa l'evoluzione attesa delle prestazioni dell'SCPA con l'evoluzione delle tecnologie CMOS. L'incoraggiante previsione enfatizza ulteriormente l'importanza dei circuiti SCPA per il futuro delle comunicazioni senza fili ad alte prestazioni

Ultra low-power SAR ADC for high resolution sensor applications, a responsive self-calibration system

embargoed_20320424Embargo per motivi di segretezza e di proprietà dei risultati e informazioni di enti esterni o aziende private che hanno partecipato alla realizzazione del lavoro di ricerca relativo alla tes

Disegno sempre anche quando penso. I luoghi e l’architettura attraverso visioni inedite di Cascarano/I Always draw even when I think. Places and architecture through unpublished Cascarano visions.

“Disegno sempre anche quando penso”. Il contributo tenta un difficile compito: presentare in uno spazio ridotto l’esperienza, l’attività creativa, poetica e tecnica di un architetto, per andare oltre la semplice catalogazione delle opere. Michele Cascarano vive disegnando e disegna vivendo luoghi, città e architetture, testimoniando un pensiero teorico. Indagare su questa figura silenziosa consente di aprire uno spaccato su alcuni aspetti della storia della professione di architetto nel secondo Nove- cento. Il contributo vuole evidenziare i caratteri e le questioni metodologiche dell’intreccio fittissimo tra fondamenti teorici e ricerca in architettura, attraverso la sua rappresentazione: disegni, acquerelli che fissano sulla carta città visitate e immaginate, tra memoria e oblio di opere senza tempo. Il lavoro di Cascarano mostra l’esistenza di una ricerca individuale intesa come opera collettiva dell’essere architetto, che ripone nell’arte del disegno un’originale esperienza della realtà e del mondo. Da que- sto fondamento egli trae l’energia e la forza rappresentativa per disegnare architetture tendenziose, collocate tra rilievo, memoria e progetto. Così l’atto del fabbricare è l’opera d’arte della creazione architettonica, e configura un mondo abitabile non soggetto alle rovine del tempo e all’incuria degli uomini. L’osservatore viene coinvolto nell’avventura vertiginosa di un pensiero: il disegno di mosaici di città è il nesso, il senso di esistenza. Pensare disegnando, per comprendere alcune realtà del mondo e renderle ideali.“I always draw even when I think”.The paper has a difficult task: to present, in a few pages, the experience, the creative, poetic and technical activity of an architect, bypassing the simple cataloging of his works. Michele Cascarano lives by drawing and, at the same time, draws by living places, cities and architectures, testifying a theoretical thought. Investigating this silent figure allows to open a cross-section on some aspects of the history of the profession of architect in the second half of the twentieth century.The paper highlights characters and methodological issues of the very close intertwining between theoretical foundations and research in architecture, through its representation: drawings, watercolors that fix on paper visited or imagined cities, between memory and oblivion of timeless works. Cascarano’s work shows the existence of an individual research intended as a collective work of being an architect, that uses the art of drawing as an original experience of the reality and of the world. From this reason, he leads to the energy and the representative strength to draw tendentious architectures, placed between survey, memory and design.Thus, the building activity is the art-work of architectural creation, and it amounts to a habitable world that is not influenced by ruins of time or negligence of men. The viewer is involved in the vertiginous adventure of a thought: the design of cities mosaics is the nexus, the sense of existence. To think by drawing, to understand some realities of the world and make them idea

Injection locked ring oscillator based digital-to-time converter and method for providing a filtered interpolated phase signal

Apparatus and methods for a digital-to-time converter (DTC) are provided. In an example, a DTC can include a phase interpolator and a ring oscillator. The phase interpolator can be configured to receive digital representations of two or more distinct phase signals, and to interpolate the digital representations of the two or more distinct phase signals to provide an interpolated output phase signal. The ring oscillator can be configured to receive the interpolated phase signal, to lock on to a frequency and a phase of the interpolated output phase signal, and to provide a filtered phase signal