1,720,980 research outputs found
An X-to-Ka band MMIC up-converter in GaAs pHEMT technology for Ka-band broadband satellite communications
No full textIn this article, an X-band to Ka-band up-converter circuit designed for the transmitting chain of Satcom-on-the-move terminals is presented. The circuit is implemented using a 0.25 μm GaAs pHEMT microwave monolithic integrated circuit commercial process. It operates at fixed LO frequency of 22 GHz, IF input frequency within the band (8-9) GHz and corresponding RF output frequency within (30-31) GHz band. The up-converter circuit is composed of a resistive FET mixer, a K-band LO buffer amplifier, and a Ka-band medium power amplifier at the RF output. The bias operating condition of the entire multifunction chip is Vdd?=?2.8 V, Idq?=?322 mA, for a power consumption of 900 mW, when the Ka-band high power amplifier (HPA) operates in linear conditions. The chip dimensions are 3.4 × 2.8 mm2. The up-converter provides more than 12 dB conversion gain over the full bandwidth, when operated with LO input power of 0 dBm and IF fixed input power of -5 dBm. It also achieves 25 dBc of LO isolation at the RF output port. The high 1 dB compression point P1dB?>?19 dBm, along with an OTOI in excess of 29 dBm, make the circuit suitable to directly drive Ka-band high power amplifiers in very linear operating conditions
Scalable Equivalent Circuit FET Model for MMIC Design Identified Through FW-EM-Analyses
No full textA scalable approach to the modeling of millimeterwave
field-effect transistors is presented in this paper. This is based
on the definition of a lumped extrinsic parasitic network, easily
scalable with both the number of fingers and the finger widths. The
identification of the extrinsic network parameters is carried out by
means of accurate full-wave electromagnetic simulations based on
the layout of a single reference device.
In the paper, the parasitic effects of the gate/drain manifolds and
of the source layout are investigated, leading to the definition of
realistic linear scaling rules.
The obtained model is experimentally validated by using a
family of 0.25- m millimeter-wave GaAs pseudomorphic HEMTs
through the accurate prediction of critical performance indicators,
such as the linear maximum power gain or the stability factor.
Despite the simplicity of the proposed model, it proves to be as
accurate as typical scalable models provided by foundries.
Straightforward application of the scalable modeling approach
to the optimum device geometry selection in a typical design
problem is also presented
A generalized CAD interface for nonlinear dynamic electron device models
No full textWe present a new netlist-compatible interface for entering and implementing nonlinear dynamic models into circuit simulators. The interface is completely general and allows to implement nonlinear models with nonlinear memory starting from model equations either in Volterra Series expansion and/or from state-space equations. A detailed description of the interface is included in the paper as well as two application examples using two different nonlinear non quasi-static models
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
Implementation of non-conventional nonlinear models for electron devices in commercial CAD tools
Full text linkIn nowadays CAD environments for integrated microwave circuit design, dedicated tools for the implementation of user defined component models are becoming more and more important. These tools are mainly oriented to the definition of equivalent circuit models.However, the need for more accurate prediction of nonlinear electron device performance pushes the modelling community towards the research of new, often non-conventional, modelling approaches (e.g., frequency-domain, behavioural, integral models, look-up-table based,state-space based, etc.). In such a context, the model implementation tools usually available may result not sufficiently flexible. The paper provides useful hints andpoints out the main limitations which can be encountered in the implementation of non-conventional electron device models. As an example, the implementation of a Nonlinear Discrete Convolution model will be considered by usingthree different advanced tools: the Model Wizard of AWR Microwave Office, the Model Development Kit and Verilog-A Language of Agilent ADS
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
Extraction of an Extrinsic Parasitic Network for Accurate mm-Wave FET Scalable Modeling on the Basis of Full-Wave EM Simulation
No full textThis paper describes a new methodology for the extraction of an extrinsic parasitic network suitable for scalable electron device models. The extraction procedure is based on the data obtained through Full-Wave Electro-Magnetic (FW-EM) analyses of the passive structure of a reference device. The new topology proposed proves to be scalable according to simple linear rules derived from geometric considerations. This new parasitic network is used together with a scalable intrinsic device model in order to predict the behavior of different 0.25 μm GaAs PHEMTs (total gate-widths between 300 and 900 μm) belonging to a standard process for millimeter-wave applications. Better accuracy with respect to conventional modeling approaches, is proved up to 80 GHz
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
X-Band GaN Power Amplifier for Future Generation SAR Systems
No full textA X-band GaN monolithic microwave integrated circuits (MMIC) High Power Amplifier (HPA) suitable for future generation Synthetic Aperture Radar systems is presented. The HPA delivers 14 W of output power, more than 38% of PAE in the frequency bandwidth from 8.8 to 10.4 GHz. Its linear gain is greater than 25 dB. For the first time an MMIC X-band HPA has been designed by directly measuring the transistor behavior at the current generator plane. In particular, optimum device load-line has been selected according to the chosen performance tradeoffs
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