911 research outputs found
An approach to harmonic load- and source-pull measurements for high-efficiency PA design
No full textHigh-efficiency power-amplifier design requires numerous efforts to investigate both input and output harmonic terminations effects. A simplified theoretical approach to clarify the relevance of such terminations is presented here, and design criteria to improve efficiency for high-frequency applications are briefly discussed. An advanced active load/source-pull test-bench has been used to validate theoretical harmonic tuning techniques, characterizing an active device. The adopted optimization strategy is presented, together with measured results obtained with a medium-power 1-mm MESFET at 1 GHz. Input second harmonic impedances effects are stressed, showing a drain efficiency spread between 37%-49% for a fixed input power level, corresponding to 1-dB compression. Finally, as predicted by the presented theory, after input second harmonic tuning, further improvements are obtained, increasing fundamental output load resistive part, demonstrating an additional drain efficiency enhancement, which reaches a level of 55% at 1-dB compression
A GaN-on-Si MMIC Power Amplifier with 10W Output Power and 35% Efficiency for Ka-Band Satellite Downlink
No full textThe design and experimental characterization of a Monolithic Microwave Integrated Circuits (MMICs) Power Amplifiers (PAs) specifically conceived for next generation Ka-band Very High Throughput Satellites (vHTS) are discussed. The chip has been implemented on a commercially available 100 nm gate length Gallium Nitride on Silicon (GaN-Si) process. The design was carried out accounting for the peculiarities of the application, therefore the selection of the devices' bias points and the matching network topologies was driven, and then accomplished, by carefully considering the thermal constraints of the technology, in order to keep the junction temperature of all devices below 160°C. The MMIC, based on a three stage architecture, has been fully characterized from 17.3 GHz to 20.2 GHz. In such a frequency range, it delivers an output power larger than 40 dBm with a power added efficiency peak higher than 40% and 22 dB of gain
A High Efficiency and Low Distortion 6 W GaN MMIC Doherty Amplifier for 7 GHz Radio Links
No full text
RF signal component separator for LINC transmitters
No full textAn experimental test bed of a novel full analogue microwave LINC signal component separator scheme is presented. The proposed experiment has been performed to validate the theory and to demonstrate the usefulness of the proposed solution, constituting the preliminary and mandatory step before a completely integrated version
Enhancing power efficiency of doherty power amplifiers using windowing based crest factor reduction technique
No full textThis paper investigates the performance of a Windowing Based Crest Factor Reduction (CFRWB) technique, to enhance the power efficiency of Radio Frequency (RF) power amplifiers. In particular, CFRWB is implemented on a Doherty Power Amplifier (DPA) in conjunction with Generalized Memory Polynomial (GMPDPD), and Volterra series based Digital Predistortion (VDPD) techniques. Key features like spectral regrowth, Peak to Average Power Ratio (PAPR) reduction, efficiency improvement and Error Vector Magnitude (EVM) have been used to measure the efficacy of the proposed method. Both simulation and experimental results show that the proposed combination of CFRWB technique with GMPDPD and VDPD is able to reduce the PAPR of the complex input signals by nearly 60%, with minimal degrading of the EVM and spectral regrowth. Moreover, such signal with reduced PAPR can be used to overdrive the DPA, allowing for a relevant average efficiency enhancement (i.e., up to 25%), while fulfilling the requirements of modern communication standards such as Wideband Code Division Multiple Access (WCDMA) and long-term evolution (LTE)
Development of integrated innovative techniques for paintings examination: The case studies of The Resurrection of Christ attributed to Andrea Mantegna and the Crucifixion of Viterbo attributed to Michelangelo's workshop
No full textThis is the accepted manuscript (post-peer reviewed) of the following final paper: "Laureti, S., Colantonio, C., Burrascano, P., Melis, M., Calabrò, G., Malekmohammadi, H., Sfarra, S., Ricci, M., Pelosi, C. , Development of integrated innovative techniques for paintings examination: The case studies of The Resurrection of Christ attributed to Andrea Mantegna and the Crucifixion of Viterbo attributed to Michelangelo's workshop, (2019) Journal of Cultural Heritage, 40, pp. 1-16, https://doi.org/10.1016/j.culher.2019.05.005
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