Multi-Way Lossless Outphasing System Based on an All-Transmission-Line Combiner
Author(s)
Barton, Taylor W.; Pednekar, Prathamesh H.; Jurkov, Alexander; Perreault, David J
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A lossless power-combining network comprising cascaded transmission-line segments in a tree structure is introduced for a multi-way outphasing architecture. This architecture addresses the suboptimal loading conditions in Chireix outphasing transmitters while offering a compact and microwave-friendly implementation compared to previous techniques. In the proposed system, four saturated power amplifiers (PAs) interact through an all-TL power-combining network to produce nearly ideal resistive load modulation of the branch PAs over a 10:1 range of output powers. This work focuses on the operation of the combining network, deriving analytical expressions for input-port admittance characteristics and an outphasing control strategy to modulate output power while minimizing reactive loading of the saturated branch amplifiers. A methodology for combiner design is given, along with a combiner design example for compact layout. An experimental four-way outphasing amplifier system operating at 2.14 GHz demonstrates the technique with greater than 60% drain efficiency for an output power range of 6.2 dB. The system demonstrates a W-CDMA modulated signal with a 9.15-dB peak-to-average power ratio with 54.5% average modulated efficiency at 41.1-dBm average output power.
Date issued
2016-03Department
Massachusetts Institute of Technology. Department of Electrical Engineering and Computer ScienceJournal
IEEE Transactions on Microwave Theory and Techniques
Publisher
Institute of Electrical and Electronics Engineers (IEEE)
Citation
Barton, Taylor W. et al. “Multi-Way Lossless Outphasing System Based on an All-Transmission-Line Combiner.” IEEE Transactions on Microwave Theory and Techniques 64, 4 (April 2016): 1313–1326 © 2016 Institute of Electrical and Electronics Engineers (IEEE)
Version: Author's final manuscript
ISSN
0018-9480
1557-9670