High efficiency digitally linearized GaN based power amplifier for 3G applications

Abstract

In this paper, a high efficiency GaN based power amplifier is designed using multi-harmonics load pull measurements. A load matching network that independently controls the load impedance at the fundamental, second and third harmonic frequencies is used for straightforward implementation. The continuously driven single-ended deep class AB biased power amplifier achieves a peak power added efficiency of 68% at saturation. It is found that the designed power amplifier exhibit highly non linear characteristics with 7 dB gain compression at saturation. Digital predistortion based linearizer is used to improve the linearity performance of the power amplifier under a WCDMA excitation (PAPR=9.8 dB). At a 10 dB output power back-off, 21% power added efficiency was measured along with 53 dBc adjacent channel leakage ratio.