Efficient spacing scheme for a linearly interpolated lookup table predistorter

This paper presents a theoretical analysis of the residual distortions in a linearly interpolated Lookup Table (LUT) predistorter, with both uniform and non-uniform spacings. It is shown that constant linearizer performance across a wide dynamic range can be achieved with a relatively small LUT, when the entries are adequately spaced and linearly interpolated. A closed form expression for the total residual distortion power is also derived. Simulation results have been included to demonstrate the capability of a constant-range, low-resolution LUT predistorter to efficiently mitigate nonlinear distortions across more than 80dB of the top average output power levels for WCDMA transmission.