A novel predistorter for highly nonlinear broadband power amplifier

In this work we propose a partitioned predistorter (PPD) to compensate the nonlinear impairments produced by a Class AB LDMOS high power amplifier (PA). This kind of PA exhibits distinct input-output characteristics depending on the power regions, making difficult to compensate the distortion with a conventional predistorter (PD). A novel memory polynomial based PPD is implemented in order to linearize both the gain expansion and compression at low and high power regimes. Each stage of the DPD works in a different input amplitude region, allowing the reduction of polynomial order needed to compensate the overall nonlinear characteristic. The performance of the proposed PPD is validated by simulations. Normalized mean squared error (NMSE) and adjacent channel power ratio (ACPR) are evaluated showing significant improvement compared with conventional PD systems.