A Bandpass Push–Pull High Power Amplifier Based on SIW Filtering Balun Power Divider

A bandpass push–pull high power amplifier (PA) based on substrate integrated waveguide (SIW) filtering balun power divider is proposed in this article. The filtering characteristic of the PA is realized by the complementary split rings resonators (CSRRs) defected in the balun based on the SIW. Inherent to the middle metal plane of the SIW balun, the 180° phase difference power division can be achieved. Due to the natural differential characteristic of the balun, the proposed design can produce second-harmonic suppression. Greater output power is obtained owing to the filtering balun power combiner. For the fabricated bandpass push–pull PA, it exhibits high-selectivity bandpass response and good PA performance with the peak power-added efficiency (PAE) of 48.7% at 38.5-dBm output power.