Design Methodology for Dual-Band Doherty Power Amplifier With Performance Enhancement Using Dual-Band Offset Lines

This paper proposes a design methodology for dual-band Doherty power amplifier (DPA) with performance enhancement using dual-band phase offset lines. In the proposed architecture, 50-dual-band offset lines with arbitrary electric lengths at two frequencies are key components, and a novel analytical design solution has been proposed for their design and implementation. The methodology is validated with the design and fabrication of a 10-W GaN-based DPA for code division multiple access and Worldwide Interoperability for Microwave Access applications at 1960 and 3500 MHz, respectively. The dual-band Doherty amplifier using the proposed design methodology has better performance than the current state of the art. The peak drain efficiency of the amplifier is 59.5% at the first frequency and 49.6% at the second frequency of operation. Compared to balanced mode operation, there is an improvement of more than 10% in drain efficiencies, around 6.5-dB back-off, at both frequencies.