1,720,959 research outputs found
Analysis and Design of Injection-Locked LC Dividers for Quadrature Generation
No full textInjection-locked LC dividers for low-power quadrature generation are discussed in this paper. Modeling the circuits as regenerative frequency dividers leads to very simple analytical expressions for the locking band, phase deviation from quadrature and phase noise. Maximizing the ratio between the injected and the biasing current is beneficial to all the above parameters whereas reducing the tank quality factor improves locking band and quadrature accuracy, though at the expense of current consumption, for given output amplitude. To validate the theory, experiments have been carried on a 0.18-mum CMOS direct conversion IC, embedding an injection-locked quadrature generator, realized for the Universal Mobile Telecommunication System. Frequency locking range as large as 24% and phase deviation from quadrature around 0.8degrees are measured while each divider consumes 2 mA. The phase noise of the quadrature generator is determined by the driving oscillator phase noise because the dividers contribution is easily made negligible up to hundreds of megahertz offset
Injection Locked Coupled VCOs for Low Phase Noise and HighAccuracy Quadrature Generation
No full textCoupled VCOs for quadrature generation allow very accurate 90' phase shifted output signal but suffer from a trade-off between phase noise and phase accuracy, leading to poor noise times power product. In this work, we propose to synchronize them by means of an additional VCO. In this way, the coupled VCOs guarantee the quadrature accuracy between output signals, whereas the synchronizing VCO sets phase noise. The design istailored to a DCS-1800 system. Prototypes, realized in a 0.18pm CMOS technology, show the following: 285MHz tuning band, 45dB minimum Image Band Rejection, -127 dBc/Hz Phase Noise at 600kHz offset while drawing l0mA from 1.W. The Phase Noise figure of merit is 185dB, 20dB better than free running quadrature VCOs
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Full text linkWe 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
Injection Locking LC Dividers for Low Power Quadrature Generation
No full textThe trade off between phase noise and quadrature accuracy, typical of coupled voltage controlled oscillators, is broken if injection locking dividers are used for I and Q generation. Based on the general behavioral modeling of regenerative frequency dividers, this paper derives analytical expressions for locking band and phase deviation from quadrature. An injection locking quadrature generator, embedded in a 0.18 μm CMOS direct conversion receiver, shows 24% frequency locking range while drawing 4 mA. The phase deviation from quadrature measured on down-converted signals is 0.8°
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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
Analysis and design of a dual band reconfigurable VCO
No full textA systematic approach to the design of reconfigurable LC VCOs is proposed in this paper. The focus is on the choice of the reactive element of the tank most suited to switch the oscillation frequency. The optimum is the component that determines the tank Q. As an example, the design of a GSM900/1800 VCO in a 0.13 μm CMOS technology, switching a series inductor, is discussed. At this frequency, the tank Q is roughly the inductor Q, and series inductor switching allows area savings with respect to parallel switching
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