Design of broadband class-F power amplifier with high-order harmonic suppression for S-band application

A broadband class-F power amplifier for an S-band handset device is integrated on a 3 × 3 × 0.82 mm³ die using an InGaP/GaAs HBT process. With LC serial harmonic traps immersed into the broadband output matching circuit, good harmonic suppression performance can be achieved. A pure resistive impedance of the matching circuit, but near zero at second and infinite at third harmonic frequency, which enhances the efficiency, is obtained across 1.8–2.5 GHz. Tested with a continuous wave (CW) signal, the PA delivers an output power of 34 dBm and achieves a PAE of 57% at 2 GHz. In addition, excellent harmonic suppression levels of less than −53 dBc across the second to fifth harmonic are obtained. (paper)