A Novel Load Modulated Power Amplifier for Extending High Efficiency Power Range

To extend the high efficiency power range (HEPR) of the power amplifier (PA), a novel load-modulated PA (LMPA) architecture is proposed in this paper. The proposed LMPA consists of a Doherty PA (DPA) and a balanced PA (PA). The output signal of the DPA is delivered into the isolation port of the output coupler of the BPA, which is in class-C mode. The DPA has a local load modulation because it is connected to the isolation port of the output coupler. The proposed LMPA can extend the HEPR greatly due to the local modulated DPA has a 6 dB HEPR. Based on the proposed architecture, a LMPA operating at 1.95 GHz is implemented in this paper. Experimental results show the maximum output power of the fabricated LMPA is 45.7 dBm. And the saturation and 13 dB back-off drain efficiencies (DEs) are 62% and 47%, respectively. Meantime, the fabricated LMPA achieves DEs of 49% and 50% at the output back-off power levels of 6 and 9 dB, respectively.