On the Modeling and Linearization of a Concurrent Dual-Band Transmitter Exhibiting Nonlinear Distortion and Hardware Impairments

This paper proposes a novel, complexity-reduced, dual-input, two-box model for the modeling and digital predistortion of a dual-band power amplifier (PA) in the presence of in-phase/quadrature (I/Q) modulator imperfections. The model is composed of two cascaded nonlinear blocks. The first block is implemented as a mildly nonlinear dual-input truncated Volterra filter, which includes second-order cross-terms for the mutual characterization of the dynamic mildly nonlinear memory effects exhibited by the dual-band PA and for the compensation of I/Q imperfections. The second block is implemented as a two-dimensional look-up table for the characterization of the static nonlinearity of the dual-band PA. The proposed model was evaluated through the excitation of the dual-band Doherty PA by two concurrent multi-carrier signals, applied at 880 MHz and 1978 GHz, in the presence of I/Q modulator imperfections. The experimental results showed the accurate performance of the proposed model in suppressing the adjacent channel error power, when compared to other state-of-the-art models, the computational complexity of the proposed model was significantly reduced, which economizes the resources utilized by the model for implementation on a digital signal processing/field-programmable gate array platform.