A wideband digital predistortion for highly linear and efficient GaN HEMT Doherty power amplifier

Abstract

Abstract In this article, we propose the wideband digital predistortion (WDPD) for a highly linear and efficient GaN HEMT Doherty power amplifier (DPA). The WDPD is composed of the memory less DPD and the memory system, which compensates for the memory effects to achieve a highly linear wideband performance. The 11th‐memoryless polynomial characterizes the behavioral model of the DPA. The AM/AM and AM/PM lookup tables and the coefficients of the memory system are determined by the Recursive Least Square algorithm. For a 2‐FA WCDMA signal with 10 MHz carrier spacing at 2.14 GHz, the adjacent channel leakage ratio at ±10 MHz offset are improved over −50 dBc without the efficiency degradation at an output power of 36 dBm. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 484–487, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24951