Research And Design Of A New Thin Film Bulk Acoustic Filter Based On PIN-PMN-PT

The fifth generation of communication technology（5G）has been developing quickly in recent years,posing tough challenges for RF front-end devices.It is urgent to achieve high frequency and large bandwidth for thin film bulk acoustic filters.The FBAR filter’s distinctive structure makes it appropriate for use in the high-frequency band,but because Al N is a small bandwidth piezoelectric material,it is challenging to meet 5G communication requirements.The effective electromechanical coupling coefficient of the FBAR resonator and the bandwidth of the filter are closely related to each other and are both influenced by the piezoelectric material.Consequently,while designing broad bandwidth FBAR filters,it is essential to use piezoelectric materials with strong electromechanical coupling coefficients.To solve the above problems,this thesis studies and designs a large bandwidth FBAR filter based on piezoelectric material 0.26Pb(In_1/2Nb_1/2)O₃-0.46Pb(Mg_1/3Nb_2/3)O₃-0.28Pb Ti O₃（PIN-PMN-PT）.The specific work includes the following parts:1.Firstly,PIN-PMN-PT piezoelectric material with ultra-high voltage electrical characteristics was selected as the piezoelectric layer on the structure of the FBAR resonator.PIN-PMN-PT piezoelectric material with a Y cut Angle of 40°was able to achieve the maximum electromechanical coupling coefficient of 26.3%through theoretical analysis,calculation,and COMSOL finite element simulation.2D and 3D models of PIN-PMN-PT piezoelectric FBAR resonator based on 40°Y-cut Angle were established.The effects of electrode material and size on the electromechanical coupling coefficient and admittance curve were studied,and the effects of electrode structure and shape on the suppression of parasitic spurious were studied.2.The Mason equivalent circuit model was created,and simulation was used to confirm the effects of various topologies and orders on the transmission properties of the FBAR filter.On the characteristic curves of the FBAR filter,the effects of various static capacitance and effective resonant areas were contrasted.This information is used to calculate the large bandwidth FBAR filter’s design index.The maximum effective resonance area of the optimized resonator is less than 220μm²,and the effective resonance area is continuously optimized using the ADS simulation software.For sound-electromagnetic co-simulation,the final layout is imported into the HFSS electromagnetic simulation program.The ultimate 3d B bandwidth of the FBAR filter is722 MHz,and its relative bandwidth is 20.7%of this.The out-of-band suppression is greater than 37d B,the in-band insertion loss is 0.56d B,and the operating frequency is3.48GHz.