Multilayer BAW Resonator Structure for Low-Loss 5G Filtering
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Solution Overview
Problem
Existing Bulk Acoustic Wave (BAW) and Surface Acoustic Wave (SAW) resonators and filters face performance issues when operating at higher 5G frequencies, including scaling problems and significant acoustic losses, making them unsuitable for advanced cellular networks.
Innovation Solution
The development of bulk acoustic wave resonator structures with alternating piezoelectric layers having varying thicknesses and orientations, integrated capacitive layers, and multilayer metal acoustic reflectors with current spreading layers to reduce electromechanical coupling and acoustic losses, facilitating operation at higher frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional BAW and SAW resonators are used for higher 5G frequencies, then device integration is simplified, but performance deteriorates due to scaling issues and significant acoustic losses
Solution Approach 1:
The resonator structure is segmented into multiple distinct layers including piezoelectric layers, piezomagnetic layers, acoustic reflectors, and current spreading layers. Each layer serves a specific function to collectively reduce acoustic losses and enable higher frequency operation, directly addressing the reliability issue while maintaining adaptability across frequency bands
Solution Approach 2:
The invention employs composite material structures combining piezoelectric materials, piezomagnetic materials, and various acoustic reflector materials in a multilayer configuration. This composite approach leverages the complementary properties of different materials to simultaneously achieve low acoustic loss and broad frequency band coverage
2Ease of manufacture
If conventional BAW resonator structures are used, then fabrication complexity is reduced, but electromechanical coupling increases causing performance degradation at high frequencies
Solution Approach 1:
The electromechanical coupling function is segmented across multiple specialized layers rather than concentrated in a single structure. The piezoelectric layers handle electrical-to-mechanical conversion, while piezomagnetic layers and acoustic reflectors manage acoustic wave propagation, thereby reducing unwanted coupling effects while maintaining manufacturability
Solution Approach 2:
Acoustic reflector layers act as intermediaries between the piezoelectric/piezomagnetic active layers and the substrate. These reflector layers mediate the acoustic wave propagation, reducing spurious modes and unwanted electromechanical coupling while preserving the straightforward fabrication process
3Speed
If resonator structures are designed for higher frequencies, then 5G network performance is improved, but acoustic losses increase significantly
Solution Approach 1:
The multilayer composite structure combines materials with complementary acoustic properties. The piezoelectric and piezomagnetic layers are paired with acoustic reflectors and current spreading layers to create a system that maintains high signal transmission speed while minimizing acoustic energy loss through constructive interference and reduced spurious modes
Solution Approach 2:
The structure converts potentially harmful acoustic energy that would otherwise be lost into useful resonant modes through the strategic placement of acoustic reflectors. The reflectors bounce acoustic energy back into the active regions, transforming what would be loss into beneficial reinforcement of the desired signal
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 proposed resonator structures achieve reduced electromechanical coupling and acoustic losses, enabling effective performance in higher frequency bands, such as those required for 5G cellular networks, with improved signal transmission and reduced energy absorption.
Implementation Method 1
a first piezoelectric layer, a first piezomagnetic layer, a second piezoelectric layer, and a second piezomagnetic layer
Implementation Method 2
a first piezomagnetic layer, a second piezomagnetic layer
Implementation Method 3
a first acoustic reflector electrode and a second acoustic reflector electrode
Implementation Method 4
Bulk Acoustic Wave (BAW) resonators have enjoyed commercial success in filter applications
Data Source
AI summary
Techniques for improving acoustic resonators and resonator structures are disclosed, including filters, oscillators and systems that may include such devices. A bulk acoustic wave (BAW) resonator may comprise a substrate. The bulk acoustic wave (BAW) may further comprise a plurality of piezoelectric layers including first, second, third and fourth piezoelectric layers acoustically coupled with one another and arranged over the substrate. The first, second, third and fourth piezoelectric layers may have respective piezoelectric axis orientations. The first, second, third and fourth piezoelectric layers may have respective thicknesses. Electromechanical coupling of the bulk acoustic wave (BAW) resonator may, but need not be limited.