A waveform engineered power amplifier design for envelope tracking

A novel load network design for limited harmonic manipulations to implement a transmission line waveform engineered radio frequency power amplifier for LTE applications is presented in this paper, with the target to achieve quasi-linear efficiency during power back-offs with harmonic iteration. The topology selection was based on accurate large signal modeling and simulation to obtain optimum microstrip line design controlling the 2^nd and 3^rd order harmonics at the transistor output terminal. The design was implemented using the Cree CGH40010F GaN HEMT at 2.14GHz. It provides a continuous wave (CW) drain efficiency of 73.7% at a saturated output power of 40.7dBm at a fixed 30V supply, but it was optimized for linearization with LTE 64QAM 20MHz modulated signal with a power-added efficiency (PAE) of 42.7% at an average output power of 34.9dBm with linearity meeting 3GPP specifications, as well as envelope tracking with almost 70% power added efficiency from the same PA.