Uyarlanabilir sayısal önbozma kullanılarak güç kuvvetlendiricilerinin doğrusallaştırılması

In most communication systems, power amplifiers are used to obtain high outputpower. The nonlinear characteristics of the power amplifier leads to the distortionof the output signal. This distortion affects the efficiency of the power amplifier.The way to reduce this effect is to linearize the power amplifier near the saturationregion where it is nonlinear. The widely used technique for the linearizationof power amplifiers is predistortion. The proposed technique for predistortionuses a LUT(look-up-table), a complex multiplier, an address calculator, delayelements and an adaptation logic. A new adaptation logic to update the LUTcoefficients, is used. The predistorter is simulated in Matlab software using abaseband model for the power amplifier. 16-QAM baseband modulation is usedto simulate the predistorter. In order to see the performance of the proposedpredistorter, hardware logic is implemented in FPGA and experimental setupwith RF circuits and RF power amplifier is used. For different LUT sizes, thealgorithm is tested and for the LUT size of 64, nearly 15 dB improvement inpower spectrum is observed. The LUT size of 64 is observed to be the optimalLUT size in the experiments.Keywords: