This paper presents a new Doherty power amplifier (DPA) configuration that employs high-efficiency switched-mode Class EF as its Main and Auxiliary cells. A blended approach is proposed to design the load network of the PA cells, in which the fundamental-frequency load impedance is obtained through load-pull analysis whereas the harmonic load impedances are set according to the Class-EF requirements. Realized using GaN HEMTs, the DPA prototype exhibits a drain efficiency (DE) of 81% at 45-dBm peak power and 68% at 6-dB back-off power, i.e. when excited using a 2.4 GHz continuous-wave signal. The proposed DPA has a 3-dB bandwidth of nearly 300 MHz within which the DE can be maintained above 68.5%. Using 16-QAM signal with 5-MHz bandwidth and 6-dB peak-to-average power ratio, the DPA shows a DE of 69.7% and an ACLR1 of -26.6 dBc at an average output power of 39.2 dBm.
|Number of pages||5|
|Journal||IEEE Transactions on Circuits and Systems II: Express Briefs|
|Early online date||03 Mar 2017|
|Publication status||Early online date - 03 Mar 2017|