Cartesian pre-distortion using a sigma delta modulator for multi-standard RF power amplifiers

The system implements a pre-distortion algorithm for a non-linear PA by placing a pseudo static forward model of a PA in the feedback path of a Sigma Delta Modulator. Performing the predistortion in this way reduces the computation overhead incurred in calculating pre-distorter weights for a given power amplifier. In this paper a Cartesian LUT is used to represent the PA model, allowing the system to compensate for PA non-linearity caused by multiple signal standards. The system was tested using 3 modulation standards and showed improvement of up to 28dB while the PA model remained constant.