Piezoelectric Isolator Structure for Breakdown-Resistant Signal Isolation
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Solution Overview
Problem
Piezoelectric materials used in isolators have poor dielectric characteristics, leading to high electric fields and low dielectric strength, making them susceptible to electric breakdown and inefficient in isolating signals.
Innovation Solution
Incorporating dielectric material layers with lower dielectric constants between piezoelectric transmitters and receivers, and using acoustic reflectors and absorbers to control surface acoustic wave propagation, thereby reducing local electric fields and increasing breakdown strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If piezoelectric materials are used in isolators, then signal transmission capability is improved, but dielectric strength deteriorates leading to susceptibility to electric breakdown
Solution Approach 1:
The patent combines piezoelectric materials with dielectric materials having different dielectric constants to create a composite structure. The piezoelectric material (e.g., lithium niobate, zinc oxide, gallium nitride) provides signal transmission capability, while the dielectric material layer (e.g., silicon nitride, aluminum nitride, boron nitride, aluminum oxide, silicon dioxide) provides high dielectric strength. This composite approach allows the isolator to maintain both good signal transmission and high breakdown voltage resistance.
Solution Approach 2:
The patent introduces a dielectric material layer as an intermediary between the piezoelectric transmitter and receiver electrodes. This intermediate layer acts as a mediator that reduces local electric field concentration while allowing acoustic wave propagation. The dielectric layer with lower dielectric constant than the piezoelectric material serves as a buffer that prevents direct electric field interaction, thereby increasing the overall dielectric strength of the isolator structure.
2Reliability
If piezoelectric materials are used in isolators, then piezoelectric coupling is improved, but local electric field concentration increases leading to breakdown
Solution Approach 1:
The patent applies local quality by creating regions with different dielectric properties at specific locations. The dielectric material layer is strategically positioned between the piezoelectric transmitter and receiver, creating a local region with lower dielectric constant that specifically addresses the electric field concentration problem without affecting the overall piezoelectric coupling. This localized modification allows the piezoelectric material to maintain its coupling capability while the dielectric layer locally reduces electric field intensity.
Solution Approach 2:
The patent changes the dielectric parameter (dielectric constant) by introducing a dielectric material layer with a lower dielectric constant than the piezoelectric material. This parameter change in the local region modifies the electric field distribution, reducing peak field concentrations that would otherwise occur in homogeneous piezoelectric structures. The thickness of the dielectric layer (e.g., 100 nm to 300 nm) is optimized to achieve the desired field reduction while maintaining acoustic coupling.
3Strength
If dielectric material layers are added to reduce electric fields, then breakdown strength is improved, but device complexity increases
Solution Approach 1:
The patent segments the isolator structure into distinct functional layers: a piezoelectric material layer and a dielectric material layer. This segmentation allows each layer to perform its specific function independently - the piezoelectric layer for signal transmission and the dielectric layer for electric field management. By dividing the structure into separate functional segments, the design achieves high breakdown strength without requiring complex integrated solutions, as each layer can be optimized and fabricated separately using standard thin-film deposition techniques.
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
Enhances isolation by minimizing electric field pockets, reducing spurious signals, and improving efficiency in piezoelectric isolators, ensuring stable operation and effective signal transmission.
Implementation Method 1
The piezoelectric effect is a phenomenon by which certain materials generate an electric charge when mechanical stress is applied to them. Conversely, these materials also exhibit mechanical deformation in response to an applied electric field.
Implementation Method 2
This effect occurs due to the arrangement of atoms within the crystal lattice of these materials. When mechanical stress is applied, it causes a displacement of positive and negative charges within the lattice structure, resulting in the generation of an electric potential across the material. This effect is reversible in that when an electric field is applied, it can cause the material to deform.
Implementation Method 3
Piezoelectric materials used in isolators have poor dielectric characteristics, leading to high electric fields and low dielectric strength. Incorporating dielectric material layers with lower dielectric constants between piezoelectric transmitters and receivers, and using acoustic reflectors and absorbers to control surface acoustic wave propagation, thereby reducing local electric fields and increasing breakdown strength.
Implementation Method 4
The inventors have developed techniques for promoting propagation of surface acoustic waves toward the receiver while limiting propagation in the opposite direction.
Data Source
AI summary
Described herein are techniques for enhancing isolation in on-chip piezoelectric-based isolators. Several techniques are described that improve isolation in piezoelectric isolators. According to an aspect of the present disclosure, a piezoelectric isolator may include structures arranged to decrease the occurrence of pockets of high electric field and/or to increase the breakdown electric field in the path from the transmitter to the receiver. Further aspects of the present disclosure relate to techniques for increasing the efficiency of piezoelectric isolators while also limiting the formation of spurious signals. The inventors have developed techniques for promoting propagation of surface acoustic waves toward the receiver while limiting propagation in the opposite direction.