1,721,287 research outputs found
A Simple Closed-Form CAD Approach for Sensitivity Analysis and Optimization of Passive Networks Against Load Variations
Full text linkThis contribution presents a CAD approach based on closed-form analytic formulas that allow for a straightforward evaluation of the sensitivity of passive networks to load variations. Despite being based on very basic formulas for 2-port networks, to the author's knowledge this approach has never been presented before in this form, nor applied to CAD optimization. Based on conformal mapping properties, the proposed technique provides the designer with simple formulas for computing and plotting sensitivity circles and maximum error due to load variations. Examples of application to biasing network optimization and matching network load-sensitivity analysis are discussed to demonstrate the effectiveness of the proposed approach
A Two-Way GaN Doherty Amplifier for 5G FR2 With Extended Back-Off Range
Full text linkThis article presents the design and experimental characterization of a two-way gallium nitride on silicon carbide (GaN-SiC) monolithic Doherty power amplifier (DPA) for deep back-off operation in the 5G FR2 band. The amplifier, including two driver stages on-chip, achieves 35-dBm output power, 30% power-added efficiency, and 16-dB gain at saturation at 29 GHz. It favorably compares with the present state of the art, maintaining a power-added efficiency higher than 27%, 28%, and 22% at 6-, 9-, and 12-dB output power back-off, respectively
A Design Approach for Bandwidth Enhancement of 3-Way Doherty PAs
Full text linkThe paper presents a comparison of two design strategies for 3-way Doherty power amplifiers, highlighting the main differences in terms of achievable performance and bandwidth behavior. The proposed approaches have been applied to carry out the design of two microwave monolithic integrated circuits (MMICs) for 28-GHz 5G applications in a 0.15μm gate length GaN-SiC technology. The experimental characterization of the bandwidth-optimized MMIC confirms the theoretical predictions, placing the chip well in line with the current state of the art
A 3-Way GaN Doherty Power Amplifier for 28 GHz 5G FR2 Operation
Full text linkThis paper presents the design, fabrication, and experimental characterization of a 3-way multi-stage Doherty amplifier working in the 5G NR FR2 bands centered at 28 GHz. The amplifier, realized in the WIN Semiconductors' 150 nm gate-length GaN-SiC integrated technology, is optimized for linearity as well as wide back-off efficient operation. The experimental characterization in continuous wave and under modulated signal excitation evidences performance well in line with the present state of the art in terms of bandwidth, power levels, efficiency, and linearity, without the need for additional pre-distortion
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
3-Way Doherty Power Amplifiers: Design Guidelines and MMIC Implementation at 28 GHz
Full text linkThis article presents the design strategy and the implementation of a three-way Doherty power amplifier (DPA3W) to enhance the efficiency at deep power back-off.
Theoretical design equations are derived, based on which design charts are drawn to explore the available design space, accounting for practical constraints related to the available technology and selected application. The proposed design strategy is demonstrated by the design, fabrication and experimental characterization of a three-way multistage Doherty amplifier optimized for efficiency peaks at 6 and 12 dB back-off. The amplifier is realized on the WIN Semiconductors 150 nm GaN-SiC high-electron-mobility transistor (HEMT) monolithic process at 28 GHz, targeting 5G applications. The prototype achieves saturated output power in excess of 34 dBm and power added efficiency of the order of 15% from 6 to 12 dB back-off, demonstrating competitive performance and a good agreement between simulations and measurements, thus validating the approach
Gallium Nitride Power Amplifiers for Ka-Band Satcom Applications: Requirements, Trends, and the Way Forward
Full text linkThe current trend in satellite communications is moving toward high carrier frequencies and complex modulated signals, which have a nonconstant envelope, such as quadrature amplitude modulation and orthogonal frequency division multiplexing. This trend has a significant impact on the design of the transmitter and in particular of the power amplifier (PA) from both the energy consumption and linearity standpoints. Energy-efficient PAs are crucial for reducing the cost of satellite transmitters. Poor efficiency can negatively impact power budget, thermal design, and weight
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