Design of a linearized and efficient doherty amplifier for C-band applications

In this contribution a 44.5 dBm gallium nitride (GaN) based Doherty amplifier for a center frequency of 4900 MHz is presented. The developed Doherty amplifier uses an unsymmetrical power division and offset lines for optimization of the load modulation over the dynamic output range. Various drain supply voltages of the carrier and the peak amplifier are used to optimize the gain. Furthermore, the error vector magnitude (EVM) and the adjacent channel leakage ratio (ACLR) are reduced by using a memoryless digital predistortion (DPD) based on lookup table (LUT) model. All this design strategies improve the linearity of the Doherty amplifier.