Multi-Element Coplanar Stripline Bandpass Filters Based on Spurline Resonators

Coplanar stripline (CPS) series connected, open circuit terminated spurline resonators are used to build and demonstrate multi-element bandpass filters. A wirebond, mode suppression technique is used to achieve good bandpass filter (BPF) characteristics with no unwanted, spurious stopbands. 1, 2, 3, 4 and 6-element BPFs are demonstrated at 4 GHz center frequency with increasing stopband roll-off, greater stopband rejection, greater than 10 dB return loss and less than 2 dB insertion loss.