1,720,972 research outputs found
A survey of MMIC active filters
Full text linkHigh-Q filters are a critical component in many systems. However, high-Q filters require very low-loss passive elements that are not compatible with monolithic technology. Therefore, filters are often implemented as off-chip components. Tunable high-Q filters require even larger space and weight, and are usually quite bulky. Active filters have been proposed in the past for a monolithic implementation. However, it is not easy to fulfil such requirements as a high dynamic range, low power consumption, low noise, wide tunability, stability, etc. With this study, we propose a survey of the main solutions presented in the literature, investigating the fulfilment of all or most requirements and their potential applications and feasibility, to be used in practical applications
E- to K-band GaAs Sub-Harmonic Mixer Design and Characterization
No full textThe design and test of an E-band (81-86 GHz) down-converter mixer for satellite communications is given in this contribution. The selected topology is the sub-harmonically pumped mixer. The MMIC is designed with VMS's 100 nm GaAs pHEMT technology. Characterization of the mixer shows 13-16 dB conversion loss, 40 dB rejection to LO pump and other intermodulation products at IF port, and simulated IIP3 of +14 dBm
W- to Ka-band Frequency Converter for Ultra-High Throughput Satellite Systems
No full textThis paper presents the design and test results of a W-to Ka-band Frequency Converter (Docon) for satellite communication application developed in Thales Alenia Space Italia (TAS-I) under a contract with the European Space Agency (ESA) operating in the frequency ranges from 81-86 GHz to 17.2-20.2 GHz. The Docon features 65 dB of conversion Gain compensated in temperature, a Noise Figure of 5.5 dB at ambient temperature, including the input isolator, and linear amplification of the useful multicarrier signal resulting in a total Third Order Intercept point (OTOI) of +30 dBm. The output spectrum is practically spurious-free in band, only showing the residual out-of-band LO signal at a level well below -40 dBm. Docons are key elements in satellite communications payloads, allowing the translation of uplink frequency to the downlink user frequency band. The rationale for exploiting the W - band is the larger and continuous bandwidth at disposal, roughly twice the one currently available in Q/V-band. Consequently, the number of user beams associated with a single gateway is almost doubled. Several custom MMICs have been developed for this project by using the space qualified PH10 GaAs process from UMS. To the best of the knowledge of the authors, this is the first Docon operating in W-band ever realised for space application
DC Power-Optimized Ka-Band GaN-on-Si Low-Noise Amplifier With 1.5 dB Noise Figure
No full textA Ka-band low-noise amplifier for low-consumption robust receivers is presented in this letter. The monolithic microwave integrated circuit (MMIC) is designed on a 100 nm GaN-on-Si technology provided by OMMIC foundry and decibel gain, average noise figure (NF) of 1.5 dB, with input-output return losses better than 15 dB in the whole 27-31 GHz design band. Large signal measurements show a OP1 dBcp of +16 dBm and survivability to RF input power verified up to +25 dBm without showing critical degradation. These performances have been achieved with only 150 mW dc power consumption in linear operating condition, 30% less than other Ka-band GaN LNAs published in the open literature
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
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
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