Two-Dimensional Cartesian Memory Polynomial Model for Nonlinearity and I/Q Imperfection Compensation in Concurrent Dual-Band Transmitters

The demand for high data rates and broadband wireless access necessitates the development of radio systems that use multiband signals. With the deployment of these systems, the radio-frequency front ends and power amplifiers (PAs) used exhibit many nonlinear effects leading to signal distortions. The use of a linearization technique is necessary to enhance the linearity-efficiency tradeoff. This brief explores new schemes suitable for the modeling and linearization of transmitters suffering from hardware imperfections when driven with dual-band signals. An enhanced and accurate 2-D Cartesian memory polynomial model (2DECMPM) is proposed to compensate for hardware impairments such as the in-phase and quadrature-phase (I-Q) imbalance and dc offset in addition to nonlinear distortion. From an accuracy perspective, the proposed model offers better compensation performance, mainly due to the use of additional cross-terms between I and Q signals compared to the 2-D joint memory polynomial model (2DJMPM). Experimental results show that the proposed 2DECMPM-based predistorter enabled superior PA linearization and I-Q imbalance compensation with a comparable complexity with the state-of-the-art 2DJMPM model.