The Use of Low-Pass Filters as Impedance Inverters for Highly Miniaturized Superconducting Bandstop Filter Designs

Low-pass filters are implemented as impedance inverters for a bandstop filter design. The choice of the order of the low-pass filter impacts the usable passband bandwidth of the bandstop filter. A great savings in size occurs when implemented with highly miniaturized low temperature superconducting lumped elements. A standard multilayer niobium based fabrication process is used to fabricate the lumped element bandstop filter. The filter is tested and suggestions are made to further improve the return loss outside of the rejection band.