Frequency Response Control in Frequency-Tunable Bandstop Filters

This letter presents a tunable bandstop filter with the capability of controlling the shape of the frequency response. The proposed filter structure can be tuned to have either a Butterworth or a Chebyshev response. The filter can also be tuned to have different center frequencies. Both the frequency response and the center frequency of the filter can be tuned by only adjusting the resonant frequency of each resonator without controlling inter-resonator coupling. Since the proposed filter structure has non-zero inter-resonator coupling, it can find its future application in reconfigurable filters which can be tuned to exhibit either a bandstop or a bandpass response.