DIGITAL PREDISTORTION SYSTEM AND METHOD FOR LINEARIZING AN RF POWER AMPLIFIER WITH NONLINEAR GAIN CHARACTERISTICS AND MEMORY EFFECTS

摘要

A system and method of digitally predistorting a transmitter that has a digital input, up-converter, and a RF amplifier is disclosed. A digital predistorter preferably employs three paths for the digital input signal: a linear path, a memoryless digital predistortion path, and a memory based digital predistortion path. The memoryless path is preferably a look up table (LUT) of gain error corrections indexed to the input magnitude or input power. The linear path is separated to preserve the dynamic range of the system and avoid quantization associated with memoryless LUT correction. The memory based digital predistortion path filters the power envelope, or higher even order modes of the input signal magnitude, employing a hierarchical filter, to produce a gain correction. The input signal is modulated by the gain error corrections produced by the memoryless and memory based paths.