Research And Implementation Of Bulk Acoustic Wave Devices For Mobile Wireless Communication

With the rapid development of wireless communication technology and the advent of the 5G era,integration and miniaturization have become the development trend of wireless RF terminals.Microelectro-mechanical bulk acoustic resonators as micro-electromechanical systems(MEMS)devices,which can only realize the miniaturization and integration of RF front-end frequency devices,have become hot topics in the 5G era.At the same time,compared with the traditional dielectric filters and SAW filters,its high resonant frequency,high Q value,and high sensitivity make it a huge application prospect in the filter field.The dissertation is based on Thin Film Bulk Acoustic Resonator(FBAR).The content mainly includes the following three points:1.This project establishes an equivalent model circuit and a finite element simulation model through theoretical analysis of the bulk acoustic wave(BAW)device.According to the optimization research method of the bulk acoustic wave resonator,a resonator with a center frequency of 1.9GHz and Q value greater than 1400 at parallel resonance point is obtained.The resonator is fabricated and measured,affected by the accuracy of the processing technology,the center frequency is 1.8GHz,and the Q value at parallel resonance point is about 900.2.A more accurate full-wave simulation model of BAW filters was established,an acoustic-electromagnetic co-simulation method was proposed to achieve accurate filter simulation,and the layout and packaging optimization design of Band3_Rx filter was completed.Research on high-bandwidth N78 band BAW filters for high-bandwidth applications.The control of the transmission zero point to meet the requirements of higher selectivity in a specific frequency band,high suppression of adjacent frequency bands and low insertion loss was realized through using the non-resonant node method to realize the generalized Chebyshev filter synthesis for the bulk acoustic wave filter design.he angled dipole with grounded metal wall is designed to extend the beamwidth of the antenna.3.The Young's modulus of the film material in BAW is affected by temperature changes,which causes the stiffness matrix to change and the longitudinal wave sound velocity changes,and finally the working frequency of BAW changes.The Mason model was modified to add temperature parameters,which realizes the modeling of the temperature equivalent circuit model of the BAW resonator,and a temperature compensation layer was added to compensate the resonator temperature offset frequency to obtain a zero frequency drift resonator.According to the linear distribution characteristics of heat flow,the equivalent thermal resistance circuit model of the filter can be extracted from the heat distribution.The equivalent thermal resistance replaces the resonator,and the node voltage difference between the thermal resistance represents the temperature difference between the resonators.This model more intuitively shows the filter temperature distribution to guide the optimization design of the filter layout.