Deriving a power amplifier linearizer from a physics-based system-level model

Abstract

The RF power amplifier (PA) is a nonlinear system with an intrinsic and dynamic feedback mechanism. The application of an adequate linearizer (which is also a nonlinear dynamic system) inserted at the input of the signal path (i.e., predistortion) is very important to maintain a linear transmission chain when the PA carries high power signals (avoiding spectral regrowth). This article presents a new PA linearizer model whose topology has support on the physical behavior of the general PA electronic circuit. As the proposed model is of a feed-forward nature, it is suited for implementation on digital hardware devices, such as field programmable gate array and digital signal processor. Validation tests were performed on the linearization of a 900 MHz PA excited with WCDMA-3GPP signals. Comparison with other state-of-the-art linearizer models is included, demonstrating very good linearization results. Moreover, this model has potential to be an adequate linearizer for a wider range of applications since it has physical support. © 2010 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2010.