Optimized load modulation network for doherty power amplifier performance enhancement

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review

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  • Shichang Chen
  • Quan Xue


Original languageEnglish
Article number6341879
Pages (from-to)3474-3481
Journal / PublicationIEEE Transactions on Microwave Theory and Techniques
Issue number11
Publication statusPublished - 2012


In this paper, a new load modulation network (LMN) is proposed for the Doherty power amplifier (DPA). By adjusting the transmission line characteristic impedances in the LMN, efficiency degradation due to the incomplete load modulation caused by the current unbalance between sub-amplifiers can be alleviated. Comprehensive theoretical analysis is conducted to investigate the impact of imperfect current profile on the overall efficiency and give rise to the judicious solution. To validate the new theory, two DPA prototypes based on GaAs pseudomorphic HEMTs are implemented for comparative purposes. Measurement results show that 8% and 13% greater power-added efficiency values are achieved at saturation and 6-dB output back-off point with the proposed method when compared with that of the conventional one. Additionally, the output 1-dB compression point is also improved by 2.9 dB. In particular, to the best of the authors' knowledge, this work provides a solution to address the inherent lower current driving ability for the peaking amplifier directly at the output part of a single-input DPA. © 1963-2012 IEEE.

Research Area(s)

  • Doherty amplifier, Load modulation network (LMN), Peak-to-average power ratio (PAPR), Power amplifier (PA), Power-added efficiency (PAE)