射频预失真器与基带预失真算法结合对行波管功率放大器线性化改善的影响

Effect on the linearity improvement of TWTA by combining RF predistortion linearizer and digital predistortion algorithm

为了保证自适应算法的效果,一般会将行波管输出功率进行一定回退,但是会降低行波管的工作效率。通过在行波管前端加入射频预失真器,在额定输入功率范围内,线性化后的行波管的非线性失真现象得到了一定程度改善,然后再进行基带自适应算法的实现。X波段行波管在输出功率回退较少的同时,达到较好的非线性失真改善效果。

In order to keep the adaptive digital predistortion algorithms valid, usually the output power level of the TWTA must be reduced, which corresponded a reduced efficiency of the TWTA. A predistortion technique was proposed by combining RF predistortion linearizer with adaptive digital predistortion algorithm. The gain and phase change of the TWTA with a RF predistortion linearizer circuit from small-signal input drive to saturated input drive were improved, re- spectively. Then the adaptive digital predistortion algorithm was used for the TWTA with the RF predistortion linearizer. The good linearity improvement can be reached with the less reduction for the output power level with this method.