Research On High Performance FBAR Filter

The main function of the filter is to filter out unwanted frequency components in the input signal so that the signal frequency components that need to be retained can pass smoothly.In the current era of rapidly evolving mobile communication technologies,band resources are increasingly strained and the interband protection band is increasingly narrow.For mobile devices,the filters used in the RF front-end must satisfy the requirements of high rectangularity,low insertion loss,high rejection,high power capacity,small size,and operation at high frequencies.The FBAR resonator has a very high value of Q,operating at frequencies up to more than 3 GHz,and a small size.Therefore,filters made of FBAR resonators are well suited to its filter requirements and have a broad prospect of development.In this thesis,we study the FBAR resonator modeling and the FBAR filter design in detail.In the modeling of FBAR resonators:1.In the aspect of acoustic response modeling,this thesis presents an improved Mason model for FBAR resonators with frame structure,which incorporates mutual inductance coupling into the piezoelectric layer model,simulates the steep change trend of Q value of the resonator near the resonant point,and reflects the parasitic resonance response of the FBAR resonator and the influence of subresonance introduced by the frame structure in the model.The performance variations of the filters are simulated more accurately.2.In the aspect of thermal response modeling,this thesis puts forward a method to calculate the dissipated power of FBAR resonator based on the FBAR filter topology structure,extracts the thermal resistance parameters based on the temperature data calculated by Icepak thermal simulation software,establishes the circuit model of FBAR filter temperature simulation in ADS software,and shortens the iteration time of thermal simulation of the filter.In terms of FBAR filter design:1.This thesis provides a systematic overview of the FBAR filter design process,including how to set reasonable design objectives,the choice of filter topology,optimization of resonator parameters,electromagnetic simulation methods for FBAR filters,and joint simulation optimization of the acoustic and electronic properties of FBAR filters.2.In this thesis,based on the FBAR processing technology of NSI,the FBAR filter of N41＿fullband band(2496 MHz-2690 MHz)is designed and fabricated,and the FBAR filter chip after packaging is welded and tested.The N41＿fullband filter designed in this thesis basically meets the requirements of the proposed high-performance FBAR filter in this topic,and the test results are in high agreement with the simulation results,which validates the feasibility of the resonator model and filter design approach.