A pruning method of joint 2D digital predistortion model for nonlinearity and I/Q imperfections in concurrent dual-band transmitters

Abstract

In this paper, we propose a new method to prune the joint 2D digital predistortion (2D-DPD) model for concurrent dual-band transmitter where in-phase and quadrature (I/Q) imbalance and local oscillator (LO) leakage often exist. The phenomenon of over compensation of the DPD model is found if too many terms in the DPD model are adopted. Thus redundant polynomial terms are removed in order to solve this problem, and meanwhile, to reduce the model complexity. Then the proposed model is evaluated on a 10W inverse class-F power amplifier operating at 940 MHz excited by two concurrent signals with center separation of 61.44MHz, in the presence of I/Q modulator imperfections. The experiment compares linearization performance and model complexity of the proposed model with other state-of-the-art models. It is shown to have the advantage of reducing the model complexity and avoiding the over compensation problem effectively, and the proposed method produces good performance on linearization and spectral regrowth suppression.