Wideband Balanced Bandpass Filter With Common-Mode Noise Absorption Using Double-Sided Parallel-Strip Line

In this letter, a wideband balanced bandpass filter (BPF) with the feature of common-mode (CM) noise absorption (CMNA) is presented. The whole circuit is realized with the double-sided parallel-strip line (DSPSL). The resistors placed at the two sides of the circuit work only when the CM signals are excited. The even/odd-mode equivalent circuits of the proposed BPF are analyzed and a systematic design method is introduced to guide the design. Finally, a practical BPF with CMNA is designed and fabricated. A good performance and the consistency between the simulation and the measured results verify the design theory.