Hybrid Acoustic Resonator Layout for Multi-Band Filter Miniaturization
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Solution Overview
Problem
The increasing number of filters in smartphones due to advanced mobile communication technologies necessitates miniaturization and modularization of filters while maintaining high performance, as conventional methods struggle to integrate different resonator types on a single substrate effectively.
Innovation Solution
A hybrid acoustic resonator is developed, integrating surface and bulk acoustic resonators on a single substrate by using a piezoelectric film with interdigital electrodes and trenches, where bulk-acoustic-wave propagation occurs between trenches with air gaps, allowing both types of resonators to operate along a transversal direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple filters are added to support more frequency bands, then communication performance is improved, but the layout area increases
Solution Approach 1:
The patent combines surface acoustic wave resonators and bulk acoustic wave resonators into a single hybrid resonator structure on one substrate. This merging of different resonator types enables multiple frequency bands to be supported while occupying less space than separate filters would require.
Solution Approach 2:
The hybrid resonator structure serves multiple functions by integrating both surface acoustic wave and bulk acoustic wave resonating capabilities in one device. This multi-functionality allows a single component to replace multiple separate filters, reducing the overall layout area while maintaining support for various frequency bands.
2Volume of moving object
If filter size is reduced for miniaturization, then space efficiency is improved, but integration of different resonator types becomes more difficult
Solution Approach 1:
The patent divides the piezoelectric film into different functional regions: a first region for surface acoustic wave resonators and a second region for bulk acoustic wave resonators. This segmentation allows each resonator type to be optimized independently while maintaining a compact overall structure, reducing filter size without excessive integration complexity.
Solution Approach 2:
The patent utilizes the thickness dimension of the piezoelectric film to accommodate different resonator structures. By arranging surface acoustic wave and bulk acoustic wave resonators in different regions of the film, the design achieves miniaturization in the planar dimensions while managing integration complexity through vertical layering.
3Reliability
If surface acoustic wave devices are used for low frequency, then performance is improved, but high frequency performance is insufficient
Solution Approach 1:
The patent employs a composite resonator structure combining surface acoustic wave and bulk acoustic wave resonators in a single hybrid device. This composite approach leverages the strengths of both technologies: surface acoustic wave resonators for low frequency performance and bulk acoustic wave resonators for high frequency performance, thereby extending the overall frequency range while maintaining reliability.
4Reliability
If bulk acoustic wave devices are used for high frequency, then performance is improved, but low frequency performance is insufficient
Solution Approach 1:
The hybrid resonator structure combines bulk acoustic wave and surface acoustic wave resonators, allowing the bulk acoustic wave portion to handle high frequency operations with excellent performance while the surface acoustic wave portion complements it for low frequency coverage, achieving broad frequency range adaptability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enables the integration of multiple resonator types on a single substrate, reducing space requirements while ensuring high performance and temperature stability, effectively addressing the need for miniaturization in smartphones.
Implementation Method 1
a piezoelectric film on a surface of the substrate
Implementation Method 2
an interdigital electrode located in a first region of a surface of the piezoelectric film facing away from the substrate
Implementation Method 3
a bulk-acoustic-wave propagation portion is formed between adjacent ones of the at least two trenches
Implementation Method 4
there is an air gap at a surface of each of the bulk-acoustic-wave electrodes facing away from the bulk-acoustic-wave propagation portion
Data Source
AI summary
A hybrid acoustic resonator. An interdigital electrode is provided in a first region of a surface of a piezoelectric film facing away from a substrate, and forms an interdigital transducer. At least two trenches are provided in a second region of the surface of the piezoelectric film facing away from the substrate. A bulk-acoustic-wave propagation portion is formed between adjacent trenches. A bulk-acoustic-wave electrode is provided on a side surface of the bulk-acoustic-wave propagation portion, and there is an air gap at a surface of the bulk-acoustic-wave electrode facing away from the bulk-acoustic-wave propagation portion. Thereby, the hybrid acoustic resonator includes both the surface acoustic resonator and the bulk acoustic resonator. An acoustic wave in the bulk-acoustic-wave propagation portion and an acoustic wave in the interdigital transducer are both transmitted along a transversal direction.