BAW Filter Raised Frame Layout for Q and Frequency Response

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Solution Overview

Problem

Achieving high performance specifications for bulk acoustic wave (BAW) devices is challenging, particularly in terms of quality factor (Q) and frequency response.

Innovation Solution

The use of bulk acoustic wave filters with a first BAW resonator having a multi-layer raised frame structure and a second BAW resonator with a single-layer or less raised frame structure, where the second resonator has less mass loading and contributes to a higher quality factor in specific frequency ranges.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a uniform raised frame structure is used in all BAW resonators, then manufacturing is simplified, but filter performance specifications (quality factor and frequency response) cannot be optimized

Engineering Contradiction:

Improvefilter performance specificationVSAvoidraised frame structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies local quality by configuring different raised frame structures for different resonators within the same filter. Specifically, one resonator has a first raised frame structure while another resonator has a second raised frame structure with different characteristics (such as different heights, materials, or geometries). This allows each resonator to be locally optimized for its specific function (series or shunt) while maintaining overall filter performance specifications.

Inventive Principle:

Principle #3Local quality

2Reliability

If mass loading is increased in the raised frame structure, then frequency response is improved, but quality factor decreases

Engineering Contradiction:

Improvequality factorVSAvoidfrequency response specification

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent implements local quality by applying different mass loading levels to different resonators based on their specific roles. The first resonator (e.g., series resonator) has a raised frame structure optimized for its frequency response requirements, while the second resonator (e.g., shunt resonator) has a different raised frame structure optimized for its quality factor requirements. This localized optimization resolves the contradiction between mass loading and quality factor.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent applies parameter changes by varying key parameters of the raised frame structure (such as height, width, material composition, or layer configuration) between different resonators. These parameter variations allow each resonator to achieve its optimal balance between mass loading effects and quality factor, thereby meeting both frequency response and quality factor specifications simultaneously.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If different raised frame structures are used for series and shunt resonators, then filter performance is optimized, but manufacturing complexity increases

Engineering Contradiction:

Improveinsertion loss and Gamma lossVSAvoidmanufacturing process

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent applies segmentation by dividing the filter into distinct resonator units, each with its own optimized raised frame structure. The series resonators and shunt resonators are manufactured as separate entities with different structural characteristics, then assembled into the complete filter. This segmentation allows for specialized manufacturing processes for each resonator type while maintaining overall manufacturing feasibility.

Inventive Principle:

Principle #1Segmentation

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 configuration enhances the quality factor of the BAW devices both below and above the resonant frequency, resulting in improved filter performance with reduced insertion loss and Gamma loss.

Implementation Method 1

A bulk acoustic wave (BAW) device can include a raised frame structure that can reflect lateral energy leakage

Methodology Applied

Scientific EffectAcoustic wave reflection: Reflection

Implementation Method 2

In BAW resonators, acoustic waves propagate in a bulk of a piezoelectric layer

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentUS12278619B2Filter with bulk acoustic wave device having raised frame structure

Publication Date: 2025.04.15 SKYWORKS SOLUTIONS INC

AI summary

A filter with bulk acoustic wave devices is disclosed. The filter includes a first bulk acoustic wave resonator and a second bulk acoustic wave resonator. The first bulk acoustic wave resonator includes a first raised frame structure. The first raised frame structure is a multi-layer raised frame structure. The second bulk acoustic wave resonator includes a second raised frame structure. The first raised frame structure has at least one more raised frame layer than the second raised frame structure.