High-Precision Digital Predistortion for Sub-6-GHz GaN Power Amplifiers Excited by a Signal With 400-MHz Modulation Bandwidth

Due to the escalating demands for signal bandwidth, one of the most promising options is to refarm sub-6-GHz spectrum by fully utilizing the power amplifiers (PAs) operating bandwidth to achieve high data rates. This letter proposes a high-precision digital predistortion (DPD) method designed for sub-6-GHz GaN PAs excited by signals with a wide modulation bandwidth, such as 400 MHz. The proposed model employs a cascading architecture comprising two blocks: the inhomogeneous nested generalized memory polynomial (IN-GMP) model, capable of effectively handling strong memory effects, and a model with segmentation characteristics, typically utilized to address complex nonlinearities. The experimental results demonstrate that the proposed high-precision model effectively compensates for the distortion of a 3.4–3.8-GHz GaN PA excited by a signal with 400-MHz modulation bandwidth.