Dual-Band Three-Way Doherty Power Amplifier Employing Dual-Mode Gate Bias and Load Compensation Network

This article presents a new method to design dual-band three-way Doherty power amplifiers (DPAs). A novel modified load modulation network (LMN) is constructed for enabling dual-mode Doherty operation with three-way configuration, providing enhanced high efficiency range in both modes. Moreover, a parallel load compensation network (LCN) is employed in the proposed three-way DPA to provide wideband performance in each operation band. A three-way dual-mode DPA using commercial gallium nitride high electron mobility transistors (GaN HEMTs) is then designed and manufactured to verify the proposed architecture. Frequency bands of 1.45-1.9 GHz in Mode I and 0.75-1.0 GHz in Mode II are achieved by the DPA, respectively. The fabricated DPA has a 9-dB output back-off (OBO) efficiency of 42.8%-57.7% and a saturated efficiency of 55.4%-70.1%. When driven by a 20-MHz long term evolution (LTE) modulated signal with 8-dB peak-to-average ratio (PAPR), the adjacent channel power ratio (ACPR) of the fabricated DPA is better than -49.9 dBc after digital predistortion at 0.9 and 1.7 GHz with average efficiency of 45.7% and 54.6%.