Research On Filter Design Based On TPoS Resonator

In this thesis,thin-film silicon-based piezoelectric(TPoS)devices are investigated.And based on MEMS processing technology,design and manufacture of TPoS resonators and filters,as well as technical research and verification of filter bandwidth expansion.As a unique structure of Lamb wave resonator,TPoS resonator has the advantages of low power consumption,small size,suitable electromechanical coupling coefficient,high quality factor,high power capacity and relatively stable mechanical structure.In addition,the processing technology of TPoS resonator is compatible with traditional CMOS technology and can realize single-chip multi-frequency output,so it has received extensive attention.This thesis begins with an in-depth study of the fundamentals of TPoS resonators,including electromechanical conversion,vibration modes,and the design-to-fabrication process.Based on the research results,TPoS resonators with various frequencies were successfully designed and fabricated on a single chip,all showing high Q value and low dynamic resistance.In addition,based on the requirements of filter design,the precise frequency control technology of TPoS resonator is researched.It is verified that the precise control of the frequency of the TPoS resonator can be achieved by overhang,while the other performance parameters of the resonator are less affected.After that,the ladder filter is designed with dual-port TPoS resonator and single-port TPoS resonator respectively.The IF narrowband filter with an operating frequency of 208 MHz was designed and fabricated using a two-port TPoS resonator.The filter performance is simulated and optimized by adding inductance,and the optimized filter has lower insertion loss and better steep drop coefficient.In addition,multiple frequency ladder filters are designed on a single chip using a single-port TPoS resonator.The filter performance is improved by using a high-Q resonator,and the area is reduced by nearly an order of magnitude compared to the SAW filter at the same frequency.Finally,aiming at the problem of small filter bandwidth caused by the small electromechanical coupling coefficient of TPoS resonator,a bandwidth-expandable filter based on the inherent capacitance of the resonator and constituted by a three-element matching network was successfully designed and fabricated.Although there are some unsolved problems in the process of device testing,theoretical simulations have successfully verified the feasibility of this technology in multiple frequency ranges,and it has shown up to 20 times the bandwidth expansion capability.