Design of a high linearity power amplifier in GaN HEMT technology

A 37.5dBm high-linearity power amplifier working in Ku band is presented. This power amplifier is fabricated in a 0.25μm gate process with GaN high electron mobility transistor. To improve the linearity characterization, two circuits were designed with different output matching network. The first one is matched to the optimum load for PAE characterization while the second is matched to the optimum load for linearity characterization which is quantized by IM3. Measured results indicate that the largest output power is up to 37.5dBm and the best PAE can get up to 36%. Measured linearity results of the two circuits are also presented. PAE of the second circuit is 2~4 lower than first one while linearity is 1~2dBc up than the first one. The results show that output matching network can be matched close to the optimum load for linearity characterization in order to get higher linearity.