Design and diagnosis of a 5 GHz 10-pole HTS bandpass filter using CPW quarter-wavelength resonators

A high temperature superconductor (HTS) 5 GHz 10-pole bandpass filter (BPF) is designed by using coplanar waveguide (CPW) quarter-wavelength resonators. The 10-pole Chebyshev BPF has a center frequency 5.0 GHz and a fractional bandwidth of 3.2%. Based on an equivalent circuit with J- and K-inverters, the filter is first designed by using an EM simulator. Next an optimization algorithm is employed to diagnose the discrepancy between the filter response calculated by the EM simulator and the equivalent circuit. Adjustment of the dimensions of the filter is made thereby. The frequency response of the adjusted filter well satisfies the design specifications.