Broadband High-Efficiency Dual-Mode Doherty Power Amplifier Using Hybrid F/F-1 Continuous-Mode Technology

A design strategy to enhance the efficiency of the dual-mode Doherty power amplifier (DPA) is proposed. The continuous multiple harmonic regulation approach is adopted to realize high efficiency of dual-mode DPA in a wide oper-ating frequency band. Multi-harmonic control and dual-mode impedance matching are performed by a single load modulation network. The DPA's operating frequency band and harmonic control type can be simultaneously switched through reciprocal gate bias. A DPA using GaN devices with continuous Class F for Mode I (1.5-2.4 GHz) and Class J/continuous inverse Class F for Mode II (1.3-1.4 GHz/2.5-2.7 GHz) is designed and implemented. The fabricated DPA achieves a measured 10.5-14.3-dB gain and 39.2-41.8-dBm saturated power. Due to the proposed strategies, 39.1%-58.2% and 55.6%-71.9% drain efficiencies are obtained respectively at 6-dB output power back-off and saturation output power for the designed DPA. For the down-link long-term evolution (LTE) signal with a channel bandwidth of 20 MHz and a peak-to-average power ratio (PAPR) of 7.5 dB, the average adjacent channel power ratio of the fabricated DPA is better than 40 dBc after digital predistortion at 1.3, 2.0 and 2.6 GHz with average output power back-off (OBO) efficiency of 37.8%, 39.3% and 43.3%.