1,720,958 research outputs found
A 22-nm FDSOI CMOS Low Noise active balun achieving < -44-dBc HD3 up to 1.5-V p-p output swing over 0.01-5.4-GHz for direct RF sampling applications
Get PDFIn this article, we propose a CMOS active balun targeting high linearity up to high voltage swing and over wide bandwidth for direct RF sampling applications. All the blocks of this active balun are derived using a common highly linear building block (HLBB). The HLBB is designed using an inverter with strong source degeneration. To increase the linearity of this HLBB further, its nonlinearity mechanisms are analyzed in detail. A bootstrapping technique is included in the HLBB to reduce the dominant nonlinearity. Furthermore, a pre-distortion technique cancels most of the non-linearity of the output driving stages. All the linearization techniques proposed are robust to process, voltage, and temperature (PVT) changes. The measured results of the active balun realized on-chip in a 22-nm FDSOI CMOS shows < - 44-dBc third harmonic distortion (HD3) up to 1.5- V p-p output swing over 0.01-5.4 GHz. The measured gain and phase errors of the balun action are less than 0.5 dB and ± 5, respectively. The chip is powered from a 5-V supply and dissipates 925 mW.</p
Wide band linearization techniques for RF receiver front-ends
Get PDFThis thesis presents wideband linearization techniques for RF receiver front-ends. The thesis is divided into two parts. The first part proposes a wideband-IF, linear, down-conversion-based receiver front-end mainly for cognitive radio applications. The second part presents a wideband, linear active balun capable of driving gigahertz ADCs up to their full-scale input voltage for direct RF-sampling applications. Driven by Moore's law, transistors have become faster and more compact, increasing the digital capability of a system significantly. The performance of the RF front-ends succeeding or preceding the digital blocks also needs to be increased to match the advances in the digital domain. Data acquisition and communication are examples of such systems where a significant increase in the performance of the RF front ends is paramount. RF receiver front-ends are one of the main constituents of these systems and this thesis focuses on increasing their linearity and bandwidth. RF receivers can be realized primarily either as down-conversion-based or as direct RF-sampling-based. This thesis contributes to increase the linearity and bandwidth in the applications involving both types of receivers.A traditional down-conversion-based receiver architecture has evolved over the decades. Several outcomes of this evolution have benefited a receiver's linearity and bandwidth. An example is a mixer-first receiver, the evolution of which has increased a receiver's achievable linearity to an extent that many recent works target to remove the pre-select filter in the receiver's signal chain. Nevertheless, while targeting high in-band linearity, existing mixer-first receiver architectures show various trade-offs with other performances. This thesis analyses a trade-off that exists between the in-band linearity and NF of the mixer-first receivers in detail, including deriving corresponding symbolic expressions and graphical illustrations. The trade-off that exists between the linearity and RF frequency range of an LNTA operating at RF frequencies is also analysed with detailed simulations. A baseband-matching-resistor noise-cancelling receiver architecture is proposed in this thesis which breaks these trade-offs. Furthermore, to achieve high linearity over a wide TIA bandwidth, a three-stage inverter-only OpAmp with 7.6GHz UGB is designed. The inverter-only design favours its redesign and reuse with the scaling of the technology. The proposed receiver realized on-chip in an FDX 22nm CMOS process measures >9dBm IIP3 over 175MHz TIA bandwidth. The measured NF varies between 2.5 to 5dB in the frequency range between 1 and 6GHz. With the recent advances, gigahertz ADCs support >8bit resolution over >4GHz. Besides the gigahertz ADC, realizing a high-performance balun preceding it is challenging. This balun needs to deliver high voltage swings to the input of the ADC with high linearity over a wide bandwidth. Existing baluns do not favour CMOS integration as they are either off-chip and passive or are fabricated using exotic non-CMOS processes. Existing CMOS active baluns mainly focus on down-conversion-based receivers and are not capable of delivering high voltage swings. A wideband CMOS active balun achieving high linearity up to high voltage swings is proposed in the second part of this thesis. The circuit consists of an LNA at the input followed by an actual balun and the driver blocks. Since the driver blocks experience higher i/o voltage swings compared to other blocks, a PVT robust pre-distorter circuit is used to reduce their distortion. All the circuits are derived from a common highly linear building block (HLBB). The HLBB is evolved from an inverter with strong source degeneration whose dominant nonlinearity mechanisms are analysed in detail. The derived symbolic expressions and simulation results show that there is a limit to increase the strength of source degeneration, after which the linearity benefits are not obtained. A bootstrapping technique is employed in the HLBB to extend this limit and continue to obtain the linearity benefits of the source degeneration. The CMOS active balun fabricated on-chip in an FDX 22nm CMOS process measures < −44dBc HD3 up to 1.5Vp-p over 0.01-5.4GHz. The measured CP1dB corresponds to 2.8Vp-p. The measurement results confirm that all the linearization techniques proposed are robust to PVT variations.<br/
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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