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 (104) that has adigital input, up-converter (108), and a RF amplifier (110) is disclosed. Adigital predistorter (100) preferably employs three paths for the digitalinput signal: a linear path (114), a memoryless digital predistortion path(116), and a memory based digital predistortion path (118). The memorylesspath (116) is preferably a look up table (LUT) of gain error correctionsindexed to the input magnitude or input power. The linear path is separated topreserve the dynamic range of the system and avoid quantization associatedwith memoryless LUT correction. The memory based digital predistortion path(118) filters the power envelope, or higher even order modes of the inputsignal magnitude, employing a hierarchical filter, to produce a gaincorrection. The input signal is modulated by the gain error correctionsproduced by the memoryless and memory based paths.