Design of Broadband Class-F Power Amplifier

This paper presents a high power and high efficiency power amplifier that can cover 4G LTE band. The transistor adopted in this work is CGH40025F, which is a GaN HEMT from Cree Company. Based on the design theory of Class F power amplifier, the harmonic control network is adopted for the input and output of the transistor, and the stepped impedance matching that often used in broadband matching circuit is applied to the fundamental matching of the input and output terminals. The second harmonic impedance is maintained in the low impedance zone, the third harmonic impedance is maintained in the high impedance zone while the fundamental impedance is matched to 50Ω, thus effectively improving the power amplifier output power, efficiency and bandwidth. The final measured results show that the drain efficiency between 62. 55% and 76% within 1. 7 to 2. 7 GHz, 20 ~41 W output power and over 10 dB gain level. Experimental results show remarkably good agreement with the simulation results.