PIECEWISE POLYNOMIAL PREDISTORTION METHOD AND APPARATUS FOR COMPENSATING NONLINEAR DISTORTION OF HIGH POWER AMPLIFIER

摘要

PURPOSE: A predistortion method using sectionally differentiated polynomials and a predistorter in a high power amplifier using the same are provided to compensate the non-linearity of a high power amplifier through section-by-section polynomial predistortion and to guarantee an output back off gain. CONSTITUTION: A predistorter comprises the first C/P(Cartesian/Polar) converter(1), an amplitude predistortion part(2), a phase predistortion part(3), a P/C converter(4), a power amplifier(5), the second C/P converter(6), an amplitude adapter(7), and a phase adapter(8). The first C/P converter(1) receives a cartesian complex signal containing an input phase component(Ii) and a quadrature component(Qi), converts it into a polar complex signal containing an amplitude component(ri) and a phase component(qi), and transfers them to the amplitude predistortion part(2) and the phase predistortion part(3) respectively. The amplitude predistortion part(2) receives the converted amplitude signal(ri) and creates a previously distorted amplitude signal(rd). The phase predistortion part(3) receives the converted phase signal(qi) and the previously distorted amplitude signal(rd) and creates a previously distorted phase signal(qd). The P/C converter(4) converts the previously distorted polar complex signals(rd, qd) into cartesian complex signals(Id,Qd) respectively and outputs them to the power amplifier(5). The power amplifier(5) amplifies the cartesian complex signals(Id,Qd) and provides them to the second C/P converter(6). The second C/P converter(6) converts the amplified signals into output complex signals to be used as feedback signals and provides them to the amplitude adapter(7) and the phase adapter(8).