1. A method comprising: distortion adjusting a signal for input to a radio frequency amplifier by processing the signal through a pre-distortion facility that contains at least one lookup table of coefficients organized into magnitude bands; wherein a portion of the coefficients in the lookup table are derived via linear interpolation of values in a simplified pre-distortion model that comprises estimation bands that represent a subset of the lookup table magnitude bands; and generating a distortion adjustment function by linearly interpolating a distortion coefficient that is not stored in the lookup table from the signal and a coefficient retrieved from a magnitude band of the lookup table that is selected based on the signal magnitude.