Resonant frequency and bandwidth tunable ring resonator employing MEMS tunable capacitors

This paper proposes a tunable resonator that can tune its resonant frequency and bandwidth independently by one type of tuning device. The tunable resonator comprises a ring resonator, variable parallel resonant circuits (VPRCs), and micro electromechanical systems (MEMS) digitally-tunable capacitors (MDTCs). Three MDTCs incorporated into the ring resonator are used to change the resonant frequency of the resonator. The VPRC works as an LC-tank circuit for tuning the bandwidth of the resonator. The proposed resonator is fabricated using a microstrip structure. The measured resonant frequency can be changed from 1.75 GHz to 1.18 GHz. The fractional bandwidth can be tuned from 2.7% to 9.6% at 1.75 GHz.