Power Amplifier Adaptive Linearization Using Predistortion with Polynomial Functions

Quadrature ampliltude modulation has high spectral efficiency but is highly sensitive to power amplifier nonlinearities. It is shown that an adaptive predistorter usig polynomial amplitude and phase predistortion functions can be used to linearize the power amplifier. The recursive least square algorithm is employed in an estimator which uses demodulated signals to estimate the required predistortion. Computer simulation results are provided and these results show that fast convergence and high spectrum improvement can be obtained using the proposed linearization method. The results are significantly better than those reported before for other linearization techniques.