Nonlinearity consideration of GaN based envelope tracking power amplifiers

GaN devices have led to power amplifiers (PA) with exceptional efficiency over very wide operating ranges. Most digital communication signals have a high peak to average ratio, resulting in excessive voltage biasing overhead most of the time. By modulating the power supply voltage to match the needs of the instantaneous RF signal, one can achieve greater efficiency, but this will impact the PA linearity. This paper presents behavioral modeling and digital predistortion techniques being used for envelope tracking GaN PA.