Outphasing combiner synthesis from transistor load pull data

A novel load-pull based outphasing combiner synthesis approach is developed. The design technique is based on the derivation of combiner network parameters in terms of the optimal load impedances at the peak power level and a predefined back-off level. The combiner is then synthesized using transmission lines or lumped element networks. The design technique is verified in a 30 W GaN HEMT outphasing transmitter demonstrator. The prototype presents a power-added efficiency of 50% at 2.1 GHz with 9 dB peak-to-average power ratio (PAPR) 20 MHz LTE signals. The related measured adjacent channel leakage ratio is -51 dBc using a low complexity digital pre-distortion linearization algorithm.