Efficiency enhanced class-F Doherty power amplifier at 3.5GHz for LTE-Advanced application

This paper presents a high-efficiency broadband GaN HEMT class-F Doherty Power amplifier at 3.5GHz for LTE-Advanced applications. The carrier and peak amplifier of the Doherty amplifier both adopts class-F design strategy to obtain higher efficiency, in which the transmission-line harmonic suppression network for controlling the second and third harmonics is employed. Measurement results show that DE of the proposed PA can achieve higher than 50% at the output power range of 40-46dBm. The efficiency is improved 10% comparing to conventional class-AB Doherty amplifier at most. The linearity performance of class-F Doherty PA is demonstrated with LTE-Advanced signals by utilizing the PA linearization technique combined of DPD and PAPR reduction techniques, the ACLR can reach -47dBc and -46dBc for 40MHz and 60MHz bandwidth respectively.