Reconfigurable Voltage Controlled Single-Band and Multiband Bandstop Filters With High Selectivity and Wide Tuning Range

This brief presents fully reconfigurable voltage controlled single-band and multiband bandstop filters (BSFs). Distributed coupling half-wavelength resonators and multimode resonators (MMRs) loaded by varactor diodes are applied to design the proposed fully reconfigurable BSFs. A MMR is equivalent to multiple single-mode resonators and its resonant characteristics are analyzed based on the even-odd-mode method. The frequencies, bandwidths, and the number of stopbands can be independently controlled by bias voltages. The frequency and bandwidth tuning ranges can be adjusted by geometrical dimensions. Moreover, the stopband suppression level is proportional to the number of resonators. For demonstration, six pairs of half-wavelength resonators with two sets of sizes are applied to design a fully reconfigurable BSF with single, dual, triple, and quadruple stopbands. Then, three pairs of MMRs with a uniform size are applied to design a fully reconfigurable BSF with single and dual stopbands. The proposed BSFs have merits of high selectivity, wide frequency and bandwidth tuning ranges, independent controls of frequencies and bandwidths, and reconfigurable number of stopbands.