Analysis and design of dual-band GaN HEMT based Doherty amplifier

A dual-band Doherty amplifier architecture is proposed and analysed. The amplifier architecture comprises a modified output combining network which results in a compact and effective design. For verification, a dual-band Doherty power amplifier (PA) was designed and implemented. Large-signal measurements highlighted the dual-band Doherty behavior of the designed PA with 6-dB output back-off efficiencies of η=49 % and η=44 %, measured at 2.0 GHz and 2.72 GHz, respectively. The designed Doherty PA was also tested with Universal Mobile Telecommunications System (UMTS) and Long Term Evolution (LTE) signals. Adjacent-channel leakage ratio (ACLR) levels of -44 dBc and -40 dBc were achieved at 2.0 GHz and 2.72 GHz, respectively, using digital pre-distortion (DPD) linearization. The corresponding efficiencies at 2.0 GHz and 2.72 GHz were η=46 % and η=37 %, respectively, with average output power of 36 dBm.