Novel design of a concurrent tri-band GaN-HEMT Doherty power amplifier

In this paper, a novel design approach of a concurrent tri-band Doherty power amplifier (DPA) for the frequency bands at 1.49 GHz, 2.14 GHz and 2.64 GHz is presented. To the best of our knowledge, this is the first time that a concurrent tri-band DPA has been successfully designed and implemented. The design concept can be extended to cover a large number of frequency bands. In order to make a tri-band DPA feasible, all passive structures involving the DPA, especially the tri-band Impedance Inverter Network (IIN), must be designed such that they fulfil the tri-band operation requirements. A tri-band approach is validated in hybrid technology using a 10 W and a 25 W GaN-HEMTs for the carrier and peaking PA, respectively. The measured results show peak drain efficiencies of 61 %, 58.1 % and 46.1 % and the corresponding 6 dB output power back-off (OBO) efficiencies of 50.3 %, 39.45 % and 28.3% and the output power of 45.2 dBm, 43 dBm and 41.5 dBm for the first, second and third band, respectively.