Analysis and design of the doherty amplifier based on class F and inverse class F amplifiers

In this article, a new Doherty amplifier using high-efficiency inverse class F and class F amplifiers is presented. The characteristics of inverse class F and class F amplifiers have been analyzed for their bias conditions and had impedances in order to identify their suitability to be the carrier or peaking amplifier in a Doherty amplifier. An inverse class F amplifier was employed for the carrier amplifier due to its superior linearity and efficiency performance over a wide range of had impedances. The class F amplifier was used for the peaking amplifier by virtue of its larger gain expansion characteristics. The proposed Doherty amplifier was configured using the implemented inverse class F and class F amplifiers for the 1 GHz band and evaluated using two-tone and downlink WCDMA signals. A state-of-the-art efficiency performance was achieved at a given linearity level: A power-added efficiency of 50.9 percent at a thirdorder intermodulation distortion level of-30 dBc from the two-tone test and 45.2 percent at an adjacent leakage power ratio of-30 dBc from the WCDMA test, respectively.