Research On RF MEMS Tunable Stop-filter On Coplanar Waveguide

With the rapid development of communication technology, RF (Radio Frequency) devices are applied more and more comprehensively in microwave field. As an indispensable and key device in the communication system, the filter has decisive effect to the performance of the system. The microwave filter manufactured with CMOS process has some defects such as poor radio-frequency performance, poor reliability and excessive loss, which limit the development of the whole system. Meanwhile, the microwave device with RF MEMS process attracts many scholars at home and abroad for its advantages in low loss, wide bandwidth, small volume and easiness to realize the integration and miniaturization.Because central conductor strip and both ground plane of the coplanar waveguide are on the same flat, it is feasible to realize the monolithic integrated circuit. Manufactured with MEMS process to form periodic structure on coplanar waveguide transmission line, the RF MEMS tunable filter has a good radio-frequency performance and can greatly reduce the volume, complexity, loss and weight of the system. The tunable filter is of vital significance for current and future communication system.This thesis focuses on the structure research of the RF MEMS tunable filter. This paper put forward a design, using the resonator and RF MEMS switch on the coplanar waveguide transmission line, to realize RF MEMS tunable band-stop filter simulated on Ku band:etch defected structure on the coplanar waveguide to realize the basic resonance unit; add a specially designed RF MEMS switch in the defected structure and realize the tunable resonance unit by controlling the height of switch; then improve the performance of the filter by the cascade of tunable units. The design in this paper can effectively solve current problems of filer such as the limited bandwidth and excessive loss and the MEMS switch, provided in this paper, has a steady performance. In the end, this paper introduces key technology of RF MEMS and provides processing steps of RF MEMS tunable band-stop filter.