Research On RF MEMS Switchable Filters Based On EBG Technology

In recent years, with rapid development of microwave/ radio communication, tunable filters play a more and more role in the frequency controlling of RF transceiver, multi-band communication system and wideband radar system. It can greatly improve the performance of equipment, such as smaller size, lighter weight and lower power consumption, by introducing the MEMS technology into the tunable filter applications. For example, in the multi-standard receiver, the size of the analog front-end subsystem can be reduced significantly and suppress the large interfering signal dynamic without affecting the filter performance because of using the tunable filter. Therefore, MEMS tunable filter will be an extremely important part in next-generation wireless communication systems, such as high-tunable, low-cost and low power consumption wireless and satellite communication network and radar, tunable navigation position recognition system and the intelligent RF front-end of smart weapons self-guided equipment.Firstly, in this paper, the method of model analyzing and CPW structure transmission characteristics is introduced based on the classical theory of microwave transmission line. The classic filter design theory and design methods are reviewed. Secondly, the principle of the EBG structure is analyzed and the slow wave, band-stop characteristics is studied based on the electromagnetic field theory. The equivalent lumped circuit parameter model of EBG is presented. Thirdly, in this paper, the electrostatic-driven MEMS switch is taken as an example to analyze and model its static and electromagnetic characteristics. According to the MEMS switch lumped model of the mechanical, the switch voltage formula is derived. Fourthly, to gain a tunable filter, the RF MEMS switch is used in EBG structure based on the CPW. The electromagnetic model of MEMS switch and the Frequency response performance is analyzed by full-wave simulation software and finite element analysis. Finally, the MEMS processing technology is introduced briefly and the possibility of the RF MEMS filter manufacture is analyzed, which proposes a feasible direction for designing the variable RF MEMS microwave filter in the furture.