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

摘要

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.