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Summary: Memory Effect Evaluation and Predistortion of Power Amplifiers
P. Draxler*, J. Deng*, D. Kimball, I. Langmore, and P.M. Asbeck
University of California, San Diego, La Jolla, CA 92093-0407
*UCSD & QUALCOMM Inc., San Diego, CA 92121
Abstract -- This paper introduces the envelope model
reference adaptive control construct to digital predistortion of RF
power amplifiers. It is used to formulate a block level
predistortion algorithm that compensates for the both
memoryless compression characteristics and deterministic
memory effects. An iterative technique of successive
approximations is used to obtain the memory effect inverse
function. The algorithm is applied to two amplifiers and
convergence is demonstrated. Qualitative results (instantaneous
input / output plots) and quantitative results (the sequence and
ensemble RMS error over the iteration sequence) are presented.
Index Terms -- Power amplifiers, memory effects, digital
predistortion , envelope Model Reference Adaptive Control
(MRAC), ensamble RMS error.
I. INTRODUCTION
In addition to requirements for extended battery life and
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