Stacked SAW Filter Structure for Wider 5G NR Passbands
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Solution Overview
Problem
Current acoustic wave filters, such as surface acoustic wave (SAW) filters, face limitations in achieving a wide enough passband to meet the high-speed transfer needs of 5G New Radio (NR) specifications, particularly in Frequency Range 1, due to the limitations of industrially available piezoelectric materials.
Innovation Solution
The implementation of a surface acoustic wave device with vertically stacked interdigital transducer (IDT) electrodes and piezoelectric layers, where the first IDT electrode is in electrical communication with a first piezoelectric layer and the second IDT electrode is in communication with a second piezoelectric layer, positioned between support substrates with an intermediate dielectric layer, enabling effective acoustic coupling and a wider passband.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If traditional SAW filter designs with single-layer piezoelectric structures are used, then the device structure remains simple and manufacturable, but the passband width is insufficient to meet 5G NR high-speed transfer requirements
Solution Approach 1:
The patent transitions from a traditional planar single-layer SAW filter structure to a vertically stacked multi-layer configuration. By stacking multiple piezoelectric layers with IDT electrodes in the vertical dimension, the device achieves wider passband width (approximately three times wider than traditional designs) while maintaining a compact footprint, effectively resolving the contradiction between passband width and device complexity
Solution Approach 2:
The patent implements a nested structure where multiple piezoelectric layers are stacked vertically, with each layer containing IDT electrodes and reflectors. The layers are nested within a common support substrate structure, with dielectric layers providing electrical isolation between stacked elements. This nested arrangement enables the device to achieve enhanced performance (wider passband) without proportionally increasing the overall device footprint
2Length of moving object
If vertically stacked multi-layer piezoelectric structure is implemented, then the passband width increases significantly, but the manufacturing complexity and precision requirements increase
Solution Approach 1:
The patent divides the device into discrete, modular layers (first piezoelectric layer, dielectric layer, second piezoelectric layer, etc.), each with specific functions. This segmentation allows for standardized manufacturing processes for each layer type and facilitates precise alignment through dedicated alignment features and patterns, reducing the overall manufacturing precision challenges compared to creating a monolithic complex structure
Solution Approach 2:
The patent introduces dielectric layers as intermediary elements between the stacked piezoelectric layers. These dielectric layers serve multiple functions: providing electrical isolation, enabling mechanical bonding between layers, and incorporating alignment features that guide precise positioning. The intermediary dielectric layers act as buffers that accommodate minor variations in layer thickness and positioning, reducing the cumulative precision requirements
3Productivity
If wider passband is achieved through stacked structure, then high-speed transfer requirements are met, but the device occupies more vertical space
Solution Approach 1:
The patent utilizes the vertical dimension to stack multiple functional layers, achieving wider passband width (approximately three times wider) within a compact vertical footprint. This vertical stacking approach allows the device to meet 5G NR high-speed transfer requirements without proportionally increasing the overall device volume, as the enhanced performance is achieved through layered integration rather than lateral expansion
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 results in a significantly wider passband width, approximately three times wider than traditional designs, while maintaining low loss and high electromechanical coupling, effectively addressing the high-speed transfer requirements of 5G NR specifications.
Implementation Method 1
a first interdigital transducer electrode in electrical communication with a first piezoelectric layer
Implementation Method 2
a second interdigital transducer electrode in electrical communication with a second piezoelectric layer, the first and second interdigital transducer electrodes positioned between at least a portion of the first piezoelectric layer and at least a portion of the second piezoelectric layer such that the second interdigital transducer electrode is configured to transduce a wave generated by the first interdigital transducer electrode
Implementation Method 3
surface acoustic wave device including: a first interdigital transducer electrode in electrical communication with a first piezoelectric layer; and a second interdigital transducer electrode in electrical communication with a second piezoelectric layer
Data Source
AI summary
A surface acoustic wave device is disclosed. The surface acoustic wave device can include a first interdigital transducer electrode that is in electrical communication with a first piezoelectric layer and a second interdigital transducer electrode that is in electrical communication with a second piezoelectric layer. The first and second interdigital transducer electrodes are positioned between at least a portion of the first piezoelectric layer and at least a portion of the second piezoelectric layer. The first and second interdigital transducer electrodes are positioned such that the second interdigital transducer electrode is configured to transduce a wave generated by the first interdigital transducer electrode. The first interdigital transducer electrode can be an input interdigital transducer electrode, and the second interdigital transducer electrode can be an output interdigital transducer electrode.