Low-Velocity SAW Structure for Miniaturized Frequency Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing SAW devices face challenges in miniaturization due to high wave velocity and interference from shear horizontal (SH) mode waves, which affect temperature stability and frequency response.
Innovation Solution
Incorporating a low velocity layer within the temperature compensation layer to reduce wave velocity and enhance displacement above the piezoelectric substrate, thereby minimizing interference from SH mode waves and improving temperature compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a conventional SAW device structure is used, then the device can operate at standard wave velocity, but the device size cannot be miniaturized due to high wave velocity and SH mode wave interference
Solution Approach 1:
The patent applies local quality by introducing a low velocity layer at specific locations within the temperature compensation layer, directly above the piezoelectric substrate and interdigital transducer. This localized modification creates regions of reduced wave velocity without affecting the entire device structure, enabling miniaturization while maintaining overall device functionality and temperature compensation performance.
Solution Approach 2:
The patent changes the physical parameter of wave velocity by incorporating a low velocity layer with different acoustic properties than the surrounding temperature compensation layer. This parameter change reduces the propagation velocity of surface acoustic waves, allowing for smaller device dimensions while maintaining the required wavelength and frequency characteristics for proper operation.
2Volume of moving object
If the wave velocity is reduced using a low velocity layer, then device miniaturization is enabled, but the complexity of the temperature compensation layer increases
Solution Approach 1:
The patent merges the temperature compensation function with the wave velocity control function by integrating the low velocity layer within the temperature compensation layer structure. This combination allows a single layered structure to simultaneously perform both temperature compensation and wave velocity reduction, eliminating the need for separate components and reducing overall device complexity despite the added functional capability.
Solution Approach 2:
The temperature compensation layer is designed to serve multiple functions: it provides temperature compensation for frequency stability and simultaneously incorporates a low velocity layer to reduce wave velocity for miniaturization. This multi-functionality reduces the need for additional separate components, balancing the increased structural complexity with enhanced device performance and compact size.
3Volume of moving object
If a low velocity layer is added to reduce wave velocity, then miniaturization is achieved, but the manufacturing process becomes more complex
Solution Approach 1:
The low velocity layer is deposited during the initial fabrication process as part of the temperature compensation layer formation, before subsequent electrode and interdigital transducer fabrication steps. This preliminary action integrates the wave velocity control function into the base structure early in manufacturing, avoiding the need for additional post-processing steps or complex assembly operations that would increase manufacturing difficulty.
Solution Approach 2:
The patent addresses manufacturing complexity by working in the vertical dimension (adding layers) rather than requiring complex lateral patterning or three-dimensional assembly. The low velocity layer is deposited as an additional thin film layer within the temperature compensation layer stack, utilizing standard thin-film deposition techniques that are compatible with existing SAW device fabrication processes, thereby minimizing increases in manufacturing complexity.
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 solution allows for miniaturization of SAW devices while maintaining reliable frequency response and temperature stability, reducing interference from SH mode waves and enhancing the effectiveness of temperature compensation.
Implementation Method 1
an interdigital transducer disposed on the piezoelectric substrate and configured to generate a surface acoustic wave in response to an electrical signal
Implementation Method 2
the temperature compensation layer having a low velocity layer disposed within it configured to reduce the velocity of a surface acoustic wave generated by the interdigital transducer
Implementation Method 3
a layer of temperature coefficient of frequency (TCF) compensating material is disposed atop the piezoelectric substrate and the electrodes
Data Source
AI summary
A low velocity surface acoustic wave device, and a method of reducing the velocity of a surface acoustic wave generated by a surface acoustic wave device are described, the device including a piezoelectric layer, an interdigital transducer disposed on the piezoelectric substrate and configured to generate a surface acoustic wave in response to an electrical, and a temperature coefficient of frequency compensation layer disposed partially on the interdigital transducer and partially on the piezoelectric substrate, the temperature coefficient of frequency compensation layer having a low velocity layer disposed within it configured to reduce the velocity of a surface acoustic wave generated by the interdigital transducer, the method including disposing a wave velocity adjustment layer, the wave velocity adjustment layer being a low velocity layer, within a temperature compensation layer of the surface acoustic wave device.