Design of a concurrent dual-band 1.8-2.4-GHz GaN-HEMT doherty power amplifier

In this paper, the design, implementation and experimental results of a high efficiency dual-band GaN-HEMT Doherty power amplifier (DPA) are presented. An extensive discussion about the design of the passive structures is presented showing different possible topologies of the dual-band DPA. One of the proposed topologies is used to design a dual-band DPA in hybrid technology for the frequency bands 1.8GHz and 2.4GHz with the second efficiency peak at 6 dB output power backoff (OBO). For a continuous wave output power of 20W, the measured power added efficiency is 64% and 54% at 1.8GHz and 2.4GHz, respectively. At 6 dB OBO, the resulting measured Power-Added Efficiency (PAE) were 60% and 44% in the two frequency bands. Linearized concurrent modulated measurement using 10MHz LTE signal with 7 dB Peak-to-Average-Ratio (PAR) at 1.8GHz and 10MHz WiMAX signal with 8.5 dB PAR at 2.4GHz shows an average PAE of 34%, at an adjacent channel leakage ratio of -48 dBc and -46 dBc at 1.8GHz and 2.4GHz, respectively.