Capacitor-Loaded Coupled Line Balanced Bandpass Filter

Balanced bandpass filter has been applied widely in modern communication systems due to their ability of differential-mode filtering function and common-mode suppression. For the balanced bandpass filter, compact size becomes essential with the increasing requirement of system miniaturization. In this paper, balanced bandpass filter based on capactior-loaded coupled microstrip lines is proposed. Benefitting from the structure, the proposed design has the advantages of compact size and low loss. A prototype of the proposed balanced bandpass filter is fabricated, and the measured results agree well with the simulated results.