Design of an X-Band GaAs MMIC Doherty amplifier accounting for device RON resistance

This contribution focus on the role played by the active device ON-resistance in the load modulation phenomena occurring in a Doherty power amplifier (DPA). This issue is analyzed from both theoretical and experimental point of view. The former demonstrates that to properly account for the ON-resistance of the Main device, a simultaneous optimization of the Auxiliary amplifier is mandatory to properly optimize the DPA performances. The theoretical results have been experimentally confirmed by presenting the design of two MMIC DPAs in GaAs technology, based on neither standard or advanced proposed approach. Both DPAs are designed to operate at X-Band (9.5GHz), showing an output power of 30dBm, while, in the overall range of 6 dB of output power back off (OBO), the achieved efficiency is no lower than 30%.