Gallium Nitride Power Amplifiers for Ka-Band Satcom Applications: Requirements, Trends, and the Way Forward
by Rocco Giofrè, Anna Piacibello, Paolo Colantonio, Vittorio Camarchia
Abstract: This article surveys various GaN corporate class AB PAs and Doherty PAs for Ka-band satellite applications, and introduces various innovations that improve performance for superior efficiency, thermal design and weight compared to TWT amplifier designs and greater outpower with superior radiation hardness compared to GaAs and SiGe designs. GaN devices operate at higher drain voltages and present easier 50-ohm matching challenges compared to GaAs or SiGe for simpler PA designs with improved radiation hardness due to GaN’s higher energy gap. Stacked-cell designs with dual-feed architectures and on-chip power combiners deliver output power exceeding 40 dBm with efficiencies exceeding 30% for many designs evaluated. GaN PAs with these capabilities are likely to replace the TWTA in many future Satcom applications.