A Broadband High Efficiency Doherty Power Amplifier Based on Quasi-ellipse Filter Structure

In order to broaden the bandwidth of the power amplifier and achieve high efficiency, a broadband Doherty power amplifier (DPA) is designed based on a quasi-elliptic filter structure. The peaking output network is designed with the quasielliptical filtering characteristics to improve the saturation efficiency and output power of the peak amplifier. And, the influence of the second harmonic current of the peaking amplifier on the harmonic load modulation of the carrier one can be reduced. In order to verify the above method, a broadband high-efficiency symmetrical DPA was designed using CGH40010F GaN transistors for 1.65-2.85 GHz frequency band. Measurement results show that the designed DPA has a saturated output power of 43.2-44 dBm and small signal gain of about 12.5 dB. The efficiency at saturation is about 53-66% and the 6 dB back-off efficiency ranges from 53 to 58%.