A Novel Doherty Transmitter Based on Antenna Active Load Modulation

This paper presents a novel Doherty transmitter architecture based on antenna active load modulation (AALM) to improve the efficiency of array transmitters, where the conventional power combiner is substituted by an antenna array. Different from conventional Doherty architecture, the active load modulation is realized by the mutual coupling between the array elements. To verify the proposed architecture, a power amplifier (PA) prototype is designed and implemented at 2.3 GHz. Experimental results show that the transmitter exhibits a double-peak efficiency profile which is similar to conventional Doherty PA. The prototype also achieves power gain of 14 dB, saturated output power of 40.5 dBm, and drain efficiency of better than 40%.