High-Efficiency Class-F Amplifier Design In the Presence of Internal Parasitic Components of Transistors

In this paper, the authors present an efficient design method for high efficiency class-F amplifiers considering active devices with internal parasitic components. Considering internal drain current/voltage waveforms observed at the internal drain current source of the transistor, harmonics control and fundamental matching circuits are optimized to have higher power-added efficiency (PAE). Two 1.2GHz amplifiers were designed using a large-signal model of an LDMOSFET: one had harmonics control circuits optimized for external current/voltage waveforms and another had them optimized for internal waveforms. Simulation of the class-F amplifiers with two different output networks was conducted. Class-F amplifiers having an output network optimized for internal waveforms had 19% higher PAE (79% versus 60%)