Reconfigurable Single-/Dual-Wideband Bandpass Filters Based on a Novel Topology

Based on a new topology, a series of single-/dual-wideband bandpass filters (SWB/DWB BPFs) with reconfigurable masses of properties are presented. The proposed design starts from a dual-wideband passive filtering structure, which owns five transmission zeros in the stopbands and three transmission poles in each passband. Then, three capacitors are employed as the tuning elements. By controlling these three capacitors, DWB BPFs with different reconfigurable properties, including three independently tunable passband edges, tunable center frequency of lower passband with fixed absolute bandwidth, tunable bandwidth of lower passband with fixed center frequency, and switchable lower passband, can be realized. In addition, SWB BPF with tunable bandwidth also can be achieved by varying the inserted capacitors. For verification, a prototype with different capacitors is designed and fabricated. As the measured and simulated results agree well with each other, a simple design approach of reconfigurable SWB/DWB BPFs can be verified.