Compact Bandpass Filter Using Two Ring Resonators and Two Open Stubs

© 2018 IEEE. A compact bandpass filter (BPF) using two ring resonators and two open stubs is proposed, where fifth-order passband with twelve transmission zeros at the stopband is realized. For demonstration, a filter example with center frequency of 2.04 GHz and 3 dB fractional bandwidth of 18.6% is designed. Good performance including high selectivity in the passband and sharp stopband rejection for the filter has been realized.