Reconfigurable bandpass filter with center frequency and bandwidth control

This article presents a bandpass filter with independent center frequency and bandwidth control. It is based on four frequency-reconfigurable resonators arranged in a series cascade of a second-order bandpass filter and a dual-behavior resonator. A measured bandpass filter response with variable bandwidth between 440 and 0 MHz is demonstrated at 3.6 GHz. The center frequency of the filter can be continuously varied between 2.76 and 3.79 GHz (1.4:1) with continuous bandwidth variation between 300 and 100 MHz (3:1) for a minimum out-of-band isolation of -15 dB and insertion loss between 0.76 and 2.5 dB.