Design and digital predistortion linearization of a wideband outphasing amplifier supporting 200 MHz bandwidth

Abstract

This paper presents a holistic approach to design and linearize a wideband outphasing power amplifier (PA) to efficiently amplify a 200 MHz bandwidth (BW) signal compliant with the Data Over Cable Service Interface Specification (DOCSIS) standard. The proposed outphasing PA, based on a load insensitive GaN HEMT class-E topology, was designed to face the trade-off between the output power control range to be covered with high efficiency and the desired BW. Operated following an isogain approach, the linearity performance is ensured by applying digital predistortion linearization, which combined with crest factor reduction (CFR) techniques can enhance the overall power efficiency. An 18.7 % average efficiency has been measured when fitting the standard in-band and out-of-band linearity requirements for a 26.3 dBm 64 QAM DOCSIS signal with 12.2 dB of PAPR.