BAW Filter Electrode Bridge Layout for Lower Ohmic Loss

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Solution Overview

Problem

Bulk Acoustic Wave (BAW) filters face increased electrical losses at higher frequencies due to thinner electrodes and smaller resonator areas, which require cascading multiple resonators, leading to additional resistance and power handling challenges.

Innovation Solution

A BAW filter structure with a conductive bridge forming an electrical loop between the medial and distal ends of an electrode, offset by an insulating volume, reduces electrical resistance and ohmic losses by creating a more conductive path and minimizing heat resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If electrode thickness is reduced to operate at higher frequencies, then frequency operation capability is improved, but electrical resistance and ohmic losses increase

Engineering Contradiction:

Improvefrequency operation capabilityVSAvoidelectrical resistance and ohmic losses

Core Design Contradiction:

SpeedVSLoss of energy

Solution Approach 1:

The conductive bridge extends in the lateral direction (parallel to the electrode surface) rather than only in the thickness direction, creating a three-dimensional conductive path that reduces resistance without requiring increased electrode thickness

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The conductive bridge serves multiple functions: it provides an alternative current path to reduce electrical resistance, acts as a thermal management path to reduce heat resistance, and maintains electrical connectivity while being offset by the insulating volume to prevent short circuits

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Speed

If resonator area is reduced for higher frequency operation, then frequency operation capability is improved, but power handling capability deteriorates requiring cascading

Engineering Contradiction:

Improvefrequency operation capabilityVSAvoidpower handling capability

Core Design Contradiction:

SpeedVSPower

Solution Approach 1:

The conductive bridge creates an additional dimensional pathway for current flow parallel to the electrode, effectively increasing the electrical conduction cross-section without increasing the resonator footprint area

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The conductive bridge merges with the electrode to form a combined conductive structure that provides multiple parallel current paths, effectively increasing the power handling capability while maintaining a compact resonator area

Inventive Principle:

Principle #5Merging (Combining)

3Power

If multiple resonators are cascaded to handle high power levels, then power handling capability is improved, but electrical resistance and device complexity increase

Engineering Contradiction:

Improvepower handling capabilityVSAvoidelectrical resistance

Core Design Contradiction:

PowerVSLoss of energy

Solution Approach 1:

The conductive bridge can be implemented as separate conductive elements (such as conductive vias or bridges) that connect to different regions of the electrode, segmenting the current path into multiple parallel channels that reduce overall resistance

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of cascading resonators in series (one-dimensional arrangement), the conductive bridge creates parallel current paths within the same resonator structure (utilizing the lateral dimension), thereby handling high power levels without increasing device complexity

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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 effectively decreases electrical losses, improves power dissipation density, and reduces the need for cascading, enhancing the performance of BAW filters, especially at higher frequencies like 5.65 GHz and 6.5 GHz.

Implementation Method 1

a piezoelectric layer between the electrodes

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

The conductive bridge forms a first electrical loop between a medial end and a distal end of the electrode. Such a configuration reduces electrical resistance, heat resistance, and/or ohmic losses

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentUS12255614B2Bulk acoustic wave filter structure with conductive bridge forming electrical loop with an electrode

Publication Date: 2025.03.18 QORVO US INC

AI summary

Disclosed is a Bulk Acoustic Wave (BAW) filter structure with a conductive bridge forming an electrical loop with an electrode for reduced electrical losses. In exemplary aspects disclosed herein, the BAW filter structure includes a transducer with electrodes, a piezoelectric layer between the electrodes, and at least one conductive bridge offset from at least a portion of one of the electrodes by an insulating volume. The conductive bridge forms a first electrical loop between a medial end and a distal end of the electrode. Such a configuration reduces electrical resistance, heat resistance, and/or ohmic losses for improved electrical loss of the BAW filter structure.