High-$Q$ Tunable Dielectric Resonator Filters Using MEMS Technology

This paper presents the design and implementation of a new class of high-Q tunable dielectric resonator (DR) filters based on microelectromechanical systems (MEMS) technology. The use of MEMS tuning elements results in the compact implementation of the proposed filters with high-Q and near to zero dc power consumption. The proposed filters consist of disk-shaped dielectric resonators with circular holes created in the center of each resonator. Three different filters are designed and measured based on different tuning elements. The first filter operates in TME mode at a center frequency of 4.72 GHz with a bandwidth of 21 MHz. MEMS contact-type switches are used as tuning elements for this filter. Measurement results demonstrate a tuning range of 160 MHz while the quality factor is above 510 (1200-510 over the tuning range). The other two implementations employ GaAs and MEMS varactors for tuning. The tunable filter with GaAs varactor has a continuous tuning range from 4.97 to 4.87 GHz with 65-MHz bandwidth and a Q value from 660 to 170. The MEMS varactor-tuned filter has a better tuning performance from 5.20 to 5.02 GHz with higher Q value from 800 to 550 over the tuning range. The proposed tuning approach is applicable to other modes at other frequencies of DR filters.