Design And Simulation Research Of The Stacked Crystal Film Bulk Acoustic Wave Filter

The developmental direction of current wireless communication system is High-frequency, large volume of data, multi-channel and narrow channel bandwidth. The terminals are becoming miniaturized, integrated and multi-purpose. With the development of these trends, the much higher request is bring up for the frequency-device in the system. The new style filters should have the characteristics such as high operating frequency, narrow bandwidth, can be integrated on-chip, low power consumption and high power handling. Surface Acoustic Wave filter and ceramic filter are primarily used in the traditional wireless communication systems; they can not meet the needs of current communication system because of large volume or low operating frequency. Thin-film bulk acoustic wave devices based on MEMS can solve the problems perfectly. Compare to ladder filter, lattice filter and Coupled Resonator Filter (CRF), the Stacked Crystal Film Bulk Acoustic Filters (SCFBAF) have many advantages, such as outband rejection, low insertion loss and narrow bandwidth, the researchers all over the world are paying attention to SCFBAF and there are commercial Bulk Acoustic Wave filter in abroad. For its structure and principle is more complex, and its performance is infacted by double piezoelectric layers, there are few domestic institutions do research on SCFBAF. So this dissertation does some research on SCFBAF.The main contents of this dissertation are devided into five parts as follow:Part one, given a brief introduction the structure and basic concept of Thin-Film Bulk Acoustic wave resonator (FBAR) and Film Bulk Acoustic Filter (FBAF), analysis cuttent situation of FBAR and FBAF home and abroad.Part two, presented the principles of SCFBAF and derived its equivalent circuit besed on one-demensional Mason model of piezoelectric vibrator with one piezoelectric layer. At last the voltage transfer fuction of SCFBAF is obtained.Part three, discussed which factors should be considered when selecting material for SCFBAF, and then compared piezoelectric material and electrode material for SCFBAF. Part four, this part is the key works of the dissertation, a series of simulations of SCFBAF are carried out with ANSYS 11.0, the Frequency-Amplitude curves of SCFBAF under different piezoelectric material, size and shape are received from the simulations. At last the influence between the performace of SCFBAF and piezoelectric material type, size and shape are achieved after analying the results. The influence relationships can be used as a reference when design more complex filters based on MEMS in the future.Part five, summaring the fabrication process of the piezoelectric layer and electrode layer, and then given out the preparation process of SCFBAF.