How to Design an Outphasing Power Amplifier with Digital Predistortion

Shigekazu KIMURA

IEICE TRANSACTIONS on Electronics   Vol.E104-C    No.10    pp.472-479
Publication Date: 2021/10/01
Publicized: 2021/04/09
Online ISSN: 1745-1353
DOI: 10.1587/transele.2021MMI0006
Type of Manuscript: Special Section INVITED PAPER (Special Section on Microwave and Millimeter-Wave Technologies)
outphasing,  Chireix combiner,  power amplifier,  high efficiency,  predistortion,  

Full Text: FreePDF

For improving the fifth-generation mobile communication system, a highly efficient power amplifier must be designed for the base station. An outphasing amplifier is expected to be a solution for achieving high efficiency. We designed a combiner, one of the key components of the outphasing amplifier, using a serial Chireix combiner and fabricated an amplifier with a GaN HEMT, achieving 70% or more high efficiency up to 9 dB back-off power in an 800 MHz band. We also fabricated a 2 GHz-band outphasing amplifier with the same design. We applied digital predistortion (DPD) to control the balance of amplifying units in this amplifier and achieved an average efficiency of 65% under a 20 MHz modulation bandwidth.