Wideband Analog Polyphase Network for Harmonic Cancellation of UHF Power Amplifier

This article describes a wideband filter-less radio frequency (RF) power amplifier (PA) with in-band harmonics suppression using a polyphase network. The novel passive polyphase (three-way three-phase) network helps in suppressing both the second and third harmonics of the PA present within the operating band. The architecture uses three extended continuous class F (CCF) PAs, which are combined using the proposed polyphase network. The output power of the overall system varies between 41.7 and 42.4 dBm from 0.65 to 2.05 GHz. The second and third harmonic suppression levels are improved by 15–28 and 12–15 dB, respectively, when compared with that of the standalone PA.