Investigation of class-F power amplifier in the presence of the second and fourth harmonics of input voltage

Abstract

In this paper, a thorough theoretical investigation of high-efficiency class-F power amplifier (PA) is undertaken to drive, considering the second and fourth harmonics of input voltage. The precise analytical expressions of the gate-source voltage, drain current, output power, and efficiency are extracted. Maximum normalized output power and maximum drain efficiency from the initial phase and amplitude of the second and fourth harmonics of input gate-voltage can be achieved. The simulation of class-F PA using a GaN CGH40010F transistor has been done to validate the theoretical analysis. Addition of the fourth harmonic gate voltage along with the second harmonic improves the output power and efficiency of the PA by 0.7 dBm and 4.1%. Based on the simulation with realistic elements, a highly efficient PA operating from 1.8 to 2.2 GHz is implemented. The fabricated PA provides an efficiency of 72–87.6%, PAE of 65–80% and an output power of 39.3–41 dBm.