POWER AMPLIFIER TIME-DELAY INVARIANT PREDISTORTION METHODS AND APPARATUS
An embodiment of the invention is a time-delay invariant predistortion approach to linearize power amplifiers in wireless RF transmitters. The predistortion architecture is based on the stored-compensation or memory-compensation principle by using a combined time-delay addressing method, and therefore, the architecture has an intrinsic, self-calibrating time-delay compensation function. The predistortion architecture only uses a lookup table to conduct both the correction of non-linear responses of a power amplifier and the compensation of any time-delay effects presented in the same system. Due to the time-delay invariant characteristic, the predistortion design has a wider dynamic range processing advantage for wireless RF signals, and therefore can be implemented in multi-carrier and multi-channel wireless systems.
1 . A predistortion system for linearizing an output of a power amplifier, the predistortion system comprising;
a first receiver that receives a first signal representative of a radio frequency (RF) modulated signal;
a second receiver that receives a feedback signal representative of at least one nonlinear characteristic of a power amplifier;
a predistortion controller that is communicatively coupled to the first receiver via a reference path, is communicatively coupled to the second receiver via a feedback path, and generates, based on at least one time-delay correction element, a correction factor to correct the at least one nonlinear characteristic of the power amplifier,
wherein the predistortion controller includes at least one lookup table that is pre-populated with the at least one time-delay correction element that compensates for a time delay between the reference path and the feedback path.