Design of broadband Class EF power amplifier based on low-pass filter matching structure

This paper proposes a broadband Class EF power amplifier based on a low-pass filter matching structure. Based on the theory of Class EF power amplifiers, the optimal fundamental load impedance required is derived. A broadband matching circuit is then designed using a low-pass filter prototype. In the meantime, a compact harmonic control circuit is proposed to meet the harmonic impedance requirements of class EF power amplifiers. In order to validate the effectiveness of the proposed method, a 2.6-3.6 GHz broadband class EF power amplifier is designed and fabricated. Measurement results show that the output power is between 40.68dBm and 41.6dBm at 1 dB compression point in 2.6-3.6 GHz. From 62% to 78% drain efficiency is obtained with gain greater than 10 dB.