Center frequency and bandwidth independently tunable filter using MEMS digitally tunable capacitors

This paper presents a bandpass filter (BPF) that can change its frequency response. The BPF employs tunable ring resonators that consist of ring resonators, parallel resonance circuits, and digitally tunable capacitors applying a micro electromechanical systems (MEMS) technology. Since the tunable ring resonator can tune its BW without shifting the resonant frequency, the BPF can change its bandwidth and center frequency independently. The tuning feature is achieved only by tunable capacitor, which can facilitate the integration of BPF and MEMS devices. Both simulated and measured characteristics confirm the independent tunability of its bandwidth and center frequency.