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    Investigation and Design of New, Efficient and Compact Load Modulation Amplifiers for 5G Base Stations. Design, Simulation, Implementation and Measurements of Radio Frequency Power Amplifiers Using Active Load Modulation Technique for More Compact and Efficient 5G Base Stations Amplifiers

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    PhD Thesis (7.015Mb)
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    Publication date
    2020
    Author
    Abdulkhaleq, Ahmed M.
    Supervisor
    Abd-Alhameed, Raed A.
    Noras, James M.
    McEwan, Neil J.
    Keyword
    Power amplifier
    Efficiency
    Load-modulation
    Quarter wavelength
    Radio frequency
    5G wireless networks
    Back-Off
    Doherty Technique
    Gain Flatness
    Linearity
    Rights
    Creative Commons License
    The University of Bradford theses are licenced under a Creative Commons Licence.
    Institution
    University of Bradford
    Department
    Faculty of Engineering and Informatics
    Awarded
    2020
    
    Metadata
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    Abstract
    High efficiency is an essential requirement for any system, where the energy can be saved with full retention of system performance. The power amplifier in modern mobile communications system consumes most of the supplied power through the dissipated power and the required cooling systems. However, as new services were added as features for the developed mobile generations, the required data rate has increased to fulfil the new requirements. In this case, the data should be sent with the allocated bandwidth, so complex modulation schemes are used to utilise the available bandwidth efficiently. Nevertheless, the modulated signal will have a Peak to Average Power Ratio (PAPR) which increases as the modulation complexity is increasing. In this case, the power amplifier should be backed off and designed to provide good linearity and efficiency over high PAPR. Among the efficiency enhancement techniques, the Doherty technique (Load modulation technique) is the simplest one, where no additional circuity nor signal processing is required. In this work, the theory of load modulation amplifiers is investigated through two asymmetrical Doherty Power Amplifiers (DPA) targeting 3.3-3.5 GHz were designed and fabricated using two transistors (25 W and 45 W). In addition, more compact load modulation amplifiers targeting sub 6-GHz bandwidth of 5G specifically 3.4-3.8 GHz is discussed including the theory of implementing these amplifiers, where different amplifier capabilities are explored. Each amplifier design was discussed in detail, in which the input and output matching networks were designed and tested in addition to the design of the stability circuit to make sure that the amplifier is stable and working according to the specified requirements. The fabricated circuits were evaluated practically using the available instrument test, whereas Microwave Office software was used for the simulation purpose, each amplifier was designed separately, where all the designed amplifiers were able to provide the targeted efficiency at different back-off power points. Besides, some additional factors that affect the designed load modulation amplifiers such as the effect of the harmonics at the back-off and mismatching the amplifier is discussed.
    URI
    http://hdl.handle.net/10454/19128
    Type
    Thesis
    Qualification name
    PhD
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    Theses

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