3.5 GHz High-Efficiency Asymmetric Doherty Power Amplifier Design Using a Complex Combining Load

In this study, a high-efficiency asymmetric Doherty power amplifier (DPA) based on a complex combining load (CCL) is presented. The CCL method extends the range of output back-off (OBO). This article provides a graphical design method using the Smith chart for the CCL-DPA load network. The proposed asymmetric DPA is designed using 6 and 10 W GaN-HEMTs for carrier and peaking amplifiers, respectively. With 3.5~3.6 GHz continuous-wave signal excitations, the implemented asymmetric CCL DPA exhibits a DE of 60.0~64.7 % and a PAE of 54.8~59.9 % at a maximum output power of 42.0~43.0 dBm. In addition, it has a DE of 51.3~51.6 %, and a PAE of 46.7~47.6 % at an output power of 35.0 dBm. Using an LTE signal with a PAPR of 7.5 dB and a signal bandwidth of 20 MHz, a power gain of 10.7~11.5 dB, a PAE of 44.0~45.1 %, a DE of 48.1~48.5 %, and an ACLR of −31.1 dBc are achieved. Using DPD linearization, ACLR is improved to −49.3/−50.4 dBc at an average power of 35.0 dBm.