Linearization of a Highly Nonlinear Envelope Tracking Power Amplifier Targeting Maximum Efficiency

This letter presents a linearization algorithm designed for envelope tracking transmitters with an optimal highly efficient envelope shaping function. Targeting high efficiency at all power regions of the PA results in a severe nonlinear input-output response, and broadening of the PA output spectrum compared with a fixed voltage, or other envelope shaping functions. A two-box modeling approach is used, where a static nonlinearity function focuses on reducing the nonlinearity of the transmitter, and a memory polynomial model is used in cascade to reduce remaining distortions. The results show a definite improvement over traditional one-box models, and is suitable for PAs exhibiting unique nonlinear responses, especially for ET applications.