Design of Wideband Doherty Power Amplifier Based on Filter Phase Shift Structure

Traditional Doherty power amplifier (DPA) based on dynamic load modulation technology is limited by λ/4 phase compensation line, and there are challenges in bandwidth expansion. In this paper, a wideband DPA based on filter phase shift structure is designed. By adopting an integrated wideband filter phase shift structure to replace the traditional λ/4 compensation line in power amplifier, it achieves phase compensation and impedance transformation over a wide bandwidth, while providing good filtering functionality. Thus, the relative bandwidth and out-of-band suppression characteristics of the DPA are improved effectively. For verification, the design prototype is processed and tested, the results show that the DPA achieves a saturation output power of 43.0 dBm~43.8 dBm, a saturation gain greater than 8 dB, a saturation drain efficiency of 54%~65%, and a drain efficiency of 44%~53% at 6 dB power back-off within the band of 2.4 GHz~3.6 GHz.