Parallel Delta-Sigma Modulator-Based Digital Predistortion of Wideband RF Power Amplifiers

Marouan Othmani, Noureddine Boulejfen, Matias Turunen, Markus Allen, Fadhel M. Ghannouchi, Mikko Valkama

Research output: Contribution to journalArticleScientificpeer-review

2 Citations (Scopus)
21 Downloads (Pure)

Abstract

In this article, we propose a new robust and highly efficient digital predistortion (DPD) concept for the linearization of wideband RF power amplifiers (PAs). The proposed approach is based on the combination of a parallelized delta-sigma modulator (DSM) and a forward model of the PA. This concept applies multi-rate techniques on a DSM that incorporates the forward PA model in its feedback loop to perform the required signal predistortion. Such a technique eliminates the need of reverse modeling and its associated problems. The multi-rate approach relaxes enormously the clock speed requirement of the DPD, which allows handling high signal bandwidths at feasible sampling rates. Moreover, enhanced performance can be achieved without the need of increasing the order of the modulator which reduces the sensitivity of the system to gain variations and phase distortions caused by the nonlinear PA characteristics. Three time-interleaved parallel DPD (P-DPD) variants are described and introduced, all of them have been shown to offer increased accuracy, and consequently better linearization performance compared to the DSM-based DPD state-of-the-art. The proposed architectures are tested and assessed using extensive real-world RF measurements at the 3.6 GHz band utilizing wideband 100 MHz 5G New Radio (NR) transmit waveforms, evidencing excellent transmit signal quality.

Original languageEnglish
Pages (from-to)705-718
Number of pages14
JournalIEEE Transactions on Circuits and Systems I: Regular Papers
Volume70
Issue number2
Early online date9 Nov 2022
DOIs
Publication statusPublished - Feb 2023
Publication typeA1 Journal article-refereed

Keywords

  • Clocks
  • Delta-sigma modulator
  • digital predistortion
  • linearization
  • Modulation
  • nonlinear distortion
  • power amplifier
  • Predistortion
  • Radio frequency
  • Radio transmitters
  • time-interleaving
  • Transfer functions
  • Wideband
  • wideband transmitters

Publication forum classification

  • Publication forum level 2

ASJC Scopus subject areas

  • Hardware and Architecture
  • Electrical and Electronic Engineering

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