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This brief presents the theory and design method of a wideband Doherty power amplifier (DPA) using inverse continuous class-F mode (ICFM). It is illustrated that continuous class-F−1 mode impedance condition can be achieved for Doherty operation using a simple load modulation network (LMN). The required LMN parameters and corresponding load modulation process are analyzed and calculated in theory. The post-matching architecture is then employed to realize the proposed ICFM-DPA with equivalent transmission line (TL) based LMN, which absorbs the parasitic and package parameters of the active devices. To validate the proposed ICFM-DPA architecture and design method, a physical DPA prototype using commercial gallium nitride (GaN) transistors is then designed and implemented with wider than 44% fractional bandwidth. The fabricated ICFM-DPA achieves saturated output power of 42.6–43.3 dBm with peak efficiency of 66.0%–74.6% throughout the target bandwidth. At 6 dB output power back-off (OBO), 57.0%–61.5% back-of efficiency is obtained by the implemented ICFM-DPA with power gain of 13.5–16 dB.

This article presents a theoretical analysis and circuit design for an enhanced dual-mode reciprocal Doherty power amplifier (DM-RDPA). To achieve bandwidth enhancement, an improved combining load design strategy is proposed, providing more accurate back-off impedance across a wider target bandwidth. Additionally, a sweeping analysis method is developed to determine optimal design parameters. The enhanced combining load design space of the proposed DM-RDPA is visualized, providing an intuitive view of the appropriate impedance solution space. To validate this enhanced DM-RDPA architecture and the corresponding design analysis method, a prototype PA was designed and fabricated using commercial GaN transistors. The implemented PA achieves two different Doherty operation bands: 0.95-1.9 GHz (66.7% fractional bandwidth) in Mode I and 0.67-0.93 GHz (32.5% fractional bandwidth) in Mode II. Drain efficiency of 47.3%-62.2% and 44.7%-62.1% is obtained by the fabricated DPA at 6 dB back-off in Mode I and Mode II, respectively. When driven by a 20 MHz modulated signal with 8 dB peak to average power ratio (PAPR), the fabricated DPA presents higher than 42% average efficiency in both Mode I and Mode II.