In this paper we propose a new structure of InxAl1-xN/GaN based HEMT with gate length of 20nm. The InAlN barrier layer is intentionally doped to boost the ‘Figure of Merit’. We obtained an Ion/Ioff ratio of 1010.1 and found that it is 105 times better than the undoped barrier conventional InAlN/AlN HEMT. This excellent ‘Figure of Merit’ of the proposed HEMT leads to low gate leakage current and extremely low parasitic capacitances and conductance than the existing conventional InAlN/AlN HEMT. Further the RF and Microwave characteristics of this proposed HEMT is presented with the help of Stern stability factor, max transducer power gain and the RF parameters are presented by Smith chart and Polar plot.