Digital predistortion of RF amplifiers using baseband injection for mobile broadband communications

Cabarkapa, M. 2014. Digital predistortion of RF amplifiers using baseband injection for mobile broadband communications. PhD thesis University of Westminster Faculty of Science and Technology

TitleDigital predistortion of RF amplifiers using baseband injection for mobile broadband communications
TypePhD thesis
AuthorsCabarkapa, M.
Abstract

Radio frequency (RF) power amplifiers (PAs) represent the most challenging

design parts of wireless transmitters. In order to be more energy efficient, PAs should operate in nonlinear region where they produce distortion that significantly degrades the quality of signal at transmitter’s output. With the aim of reducing this distortion and improve signal quality, digital predistortion (DPD) techniques are widely used. This work focuses on improving the performances of DPDs in modern, next-generation

wireless transmitters. A new adaptive DPD based on an iterative injection approach is developed and experimentally verified using a 4G signal. The signal performances at transmitter output are notably improved, while the proposed DPD does not require large digital signal processing memory resources and computational complexity. Moreover, the injection-based DPD theory is extended to be applicable in concurrent dual-band wireless transmitters. A cross-modulation problem specific to concurrent dual-band transmitters is investigated in detail and novel DPD based on simultaneous injection of intermodulation and cross-modulation distortion products is proposed. In order to mitigate distortion compensation limit phenomena and memory effects in highly

nonlinear RF PAs, this DPD is further extended and complete generalised DPD system for concurrent dual-band transmitters is developed. It is clearly proved in experiments that the proposed predistorter remarkably improves the in-band and out-of-band

performances of both signals. Furthermore, it does not depend on frequency separation between frequency bands and has significantly lower complexity in comparison with previously reported concurrent dual-band DPDs.

Year2014
FileMilan_CABARKAPA_2014.pdf
Publication dates
Completed2014

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Permalink - https://westminsterresearch.westminster.ac.uk/item/8yq22/digital-predistortion-of-rf-amplifiers-using-baseband-injection-for-mobile-broadband-communications


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