Design of Dual-Band Doherty Power Amplifier Using a New Phase Compensation Technique

In this brief, a novel methodology for designing a dual-band Doherty power amplifier (DPA) is proposed by using different current combining phases between the carrier and peaking power amplifiers (PAs) at different operating frequencies. It is illustrated that, by configuring appropriate dual-band current combining phases, an equivalent quarter-wavelength network can be used to replace the dual-band impedance inverter network (IIN) for dual-band Doherty operation. The required high-efficiency impedance conditions of carrier PA at output back-off (OBO) level are analyzed in detail based on the proposed architecture. To validate the proposed method, a dual-band DPA employing commercial GaN devices is designed and implemented. The fabricated DPA achieves 67%/70% efficiencies for saturated power level at 1.8/2.6 GHz. At 6-dB OBO level, the measured efficiencies are 56%/59% at 1.8/2.6 GHz, respectively.