SAW Filter Dielectric Channels for Spurious Mode Suppression

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Solution Overview

Problem

Designing an acoustic filter that provides effective filtering for high-frequency applications above 2 GHz while maintaining spurious modes below certain levels is challenging, as existing techniques like customizing electrode structures become impractical or costly due to lithographic constraints.

Innovation Solution

Implementing a surface-acoustic-wave filter with dielectric material disposed in a piezoelectric layer, using channels within the trap region to operate in a piston mode, which suppresses spurious modes across a wider frequency range and is easier to manufacture.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If electrode structure mass is increased to suppress spurious modes, then spurious mode attenuation is improved, but manufacturing complexity and cost increase due to lithographic constraints

Engineering Contradiction:

Improvespurious mode attenuationVSAvoidelectrode structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

A dielectric material is introduced as an intermediary element within channels in the piezoelectric layer to suppress spurious modes. This dielectric mediator provides the necessary mass loading effect without requiring complex electrode structure modifications, thereby achieving spurious mode attenuation while maintaining manufacturing simplicity.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces the mechanical approach of increasing electrode mass with a dielectric material insertion approach. The dielectric material in the channels provides the necessary acoustic impedance modification to suppress spurious modes without requiring additional metal deposition or complex electrode patterning, thus substituting a simpler manufacturing process for a previously complex mechanical solution.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If electrode structure is customized to suppress spurious modes, then filtering performance is improved, but ease of manufacture deteriorates due to lithographic constraints at high frequencies

Engineering Contradiction:

Improvefiltering performanceVSAvoidmanufacturing ease

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The piezoelectric layer is segmented to include channels that accommodate dielectric material. This segmentation allows the dielectric to be positioned precisely at locations that suppress spurious modes without requiring complex modifications to the electrode structure, thereby maintaining manufacturing ease while improving filtering performance.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The dielectric material serves as an intermediary that achieves spurious mode suppression without requiring complex electrode customization. This intermediary approach simplifies the manufacturing process by using standard dielectric deposition techniques rather than complex lithographic patterning of electrode structures.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If dielectric material is disposed in piezoelectric layer channels, then spurious mode attenuation is improved across wider frequency range, but device structure complexity increases

Engineering Contradiction:

Improvespurious mode attenuationVSAvoiddevice structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Dielectric material is placed locally within channels at specific positions in the piezoelectric layer where spurious modes are generated. This localized placement provides targeted spurious mode attenuation without requiring complex structures throughout the entire device, thereby achieving wide frequency range suppression with minimal added complexity.

Inventive Principle:

Principle #3Local quality

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

The dielectric material in the piezoelectric layer effectively attenuates spurious modes and reduces performance degradation during manufacturing, making it suitable for high-frequency applications.

Implementation Method 1

a surface-acoustic-wave filter with a piezoelectric layer, an electrode structure, and dielectric material. The piezoelectric layer has at least one channel.

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

Dielectric material is disposed in the channel and enables the surface-acoustic-wave filter to operate in a piston mode. With the dielectric material at least partially embedded within the piezoelectric layer, the surface-acoustic-wave filter can attenuate spurious modes across a wider range of frequencies

Methodology Applied

Scientific EffectDielectric material absorption: Absorption (EM radiation)

Data Source

PatentUS12401339B2Surface-acoustic-wave (SAW) filter with dielectric material disposed in a piezoelectric layer

Publication Date: 2025.08.26 RF360 SINGAPORE PTE LTD

AI summary

An apparatus is disclosed for implementing a surface-acoustic-wave (SAW) filter with dielectric material disposed in a piezoelectric layer. In an example aspect, the apparatus includes a surface-acoustic-wave filter with a piezoelectric layer, an electrode structure, and dielectric material. The piezoelectric layer has at least one channel. The dielectric material is disposed in the at least one channel of the piezoelectric layer and is at least partially covered by the electrode structure.