Linearity enhancement for the RF class-E power amplifiers using duty-cycle modulation at the feed-forward path

A linearity improved class-E power amplifier using duty-cycle modulation(DCM) is proposed at 2.4 GHz. The main class-E amplifier is combined with the auxiliary duty-cycle modulated class-E amplifier to enhance the linearity with suppressing the harmonics. The duty-cycle modulation is employed for the auxiliary amplifier to generate harmonics which cancel the main amplifierpsilas harmonics at the combiner. It is important to create the harmonics needed to suppress the main amplifierpsilas harmonics by controlling gate voltage of the auxiliary amplifier. The measured maximum output power at the fundamental frequency shows 28.8 dBm, whereas the PAE shows 53 % with 14 dBm input power excited. The ACPR is improved by 12 dB compared to that of the class-E amplifier without duty-cycle modulation.