Method for adjusting frequency of resonator in bulk acoustic wave filter and bulk acoustic wave filter

Abstract

The invention relates to the technical field of filters, in particular to a method for adjusting the frequency of a resonator in a bulk acoustic wave filter and the bulk acoustic wave filter. According to the method, the frequency of the resonator is adjusted by adjusting the area of a mass load layer on the surface of an upper electrode of the resonator, and further the mass load capacity is adjusted. According to the technical scheme, the method for adjusting the frequency of the resonator in the bulk acoustic wave filter and the bulk acoustic wave filter have the advantages of being low incost, simple in process and free of deterioration of the performance of the resonator, and meanwhile, the in-band performance and the out-band performance of the filter can be improved by utilizing the diversity of the frequency and the electromechanical coupling coefficient.

Description

technical field [0001] The invention relates to the technical field of filters, in particular to a method for adjusting the frequency of a resonator in a bulk acoustic wave filter and the bulk acoustic wave filter. Background technique [0002] With the development of communication systems, the requirements for filter performance of RF front-end systems are gradually increasing. It is one of the most important means to improve the performance of the filter through design optimization. For filters, passband and out-of-band transmission characteristics are realized by forming a certain frequency difference between series and parallel connections. The design of the passband of the filter needs to ensure that it matches well with the port impedance as much as possible to ensure the passage of the signal, and the design of the out-of-band needs to ensure that it does not match the port impedance as much as possible to block the passage of the signal. Therefore, the matching cha...

AI Technical Summary

Problems solved by technology

Achieving multiple frequencies through multiple layers of mass loading will increase the cost on the one hand, including the cost of the photolithography plate and the processing cost of the multi-step process; on the other hand, due to the limitation of processing accuracy, the frequency error between different mass loading layers will increase, will seriously deteriorate the performance of the filter

A variety of electromechanical coupling coefficients are mainly adjusted by the thickness of the piezoelectric layer and the dielectric constant of the material. For the same filter, the thickness and material of the piezoelectric layer are the same, and the electromechanical coupling coefficient is relatively fixed. By changing the resonator The structure to fine-tune the electromechanical coupling coefficient will sacrifice the performance of some resonators

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