Nonlinearity Modeling of a Chireix Outphasing Power Amplifier

This paper presents the nonlinearity modeling of a 2.14-GHz gallium nitride Chireix outphasing power amplifier (PA). The outphasing PA consists of two branches of class-F PAs achieving high efficiency and good phase linearity and a transmission-line-based Chireix power combiner. An analytical model of outphasing PAs with a Chireix power combiner is developed to explain observed distortion due to the combiner. The validity and accuracy of the proposed analytical model are demonstrated by comparing with simulated and measured results of the outphasing PA with 10-MHz long term evolution (LTE) signal. Furthermore, measurements with 5-/10-MHz LTE signals are performed to demonstrate the correction of the nonlinearity of the outphasing PA using linearization techniques.