1-2 GHz Doherty Power Amplifier Applying a Simplified Load Network and Composite Output Back-off Extension Techniques

This paper presents a broadband Doherty power amplifier (DPA) with an extended output power back-off (OBO) and a simplified output matching network (OMN) by merging parallel components and replacing lumped components with an equivalent transmission line. The circuit parameters defining the structure of the OMN were derived from the ABCD matrices. For the broadband design, the structure with the widest fractional bandwidth (FBW) was selected among the eight structures with different combinations of circuit parameters. Under continuous wave (CW) signal, the implemented DPA exhibited DE of 50.1~76.0 % at a peak output power of 40.5~42.8 dBm, DE of 40.2~54.4 %, and power gain of 11.3~14.6 dB at an 8 dB back-off output power for the band of 1.0~2.0 GHz where the fractional bandwidth was 66.7 %. In the case of an LTE signal with a channel bandwidth of 20 MHz and a peak-to-average power ratio (PAPR) of 8 dB, DE of 42.1~52.7 %, power gain of 10.3-13.2 dB, and ACLR of −35.7~−27.5 dBc were exhibited.