Effect and adaptive correction of impedance mismatch between antenna and power amplifier on digital predistortion

• Published in: 2013 IEEE 11th International New Circuits and Systems Conference (NEWCAS) pp. 1 - 4
• Main Authors: Mbaye, Amadou, Baudoin, Genevieve, Villegas, Martine, Gotthans, Tomas
• Format: Conference Proceeding
• Language: English
• Published: IEEE 01-06-2013
• Subjects: Antenna measurements; Couplers; Impedance; Predistortion; Reflector antennas
• DOI: 10.1109/NEWCAS.2013.6573622
• ISBN: 9781479906185; 1479906182

Digital predistortion (DPD) is a powerful and cost-effective technique to linearize Power Amplifier (PA). In radio-frequency emitters, the PA and antenna are contiguous and impedance mismatch between the two is likely to occur during emission. DPD linearization performances may be seriously degraded as a result. In this paper, firstly, we propose a new model representing the effects of impedance mismatch between PA and antenna block on the feedback signal that is measured with a coupler to adapt the predistortion. That model takes into account the coupler directivity. Secondly, we study the effect of antenna mismatch on adaptive predistortion and thirdly we propose a solution based on an adaptive correction gain to preserve linearization performances under mismatch conditions. These proposals are evaluated and validated on signals from a 120 W Doherty PA.