Parametric quality factor enhancement for highly-selective miniaturized BPFs

Negative-resistance parametric amplification was applied to a semi-lumped microstrip resonator for "recovering" their quality factor. Then, a narrowband (2% fractional bandwidth), highly-selective (fifth-order) bandpass filter (BPF) based on such resonator was designed to demonstrate that zero low insertion loss characteristic can be achieved at the center of the passband.