SAW Filter Electrode Pitch and TiO2 Layer for Temperature Stability
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Solution Overview
Problem
Existing acoustic wave filters face challenges in reducing size while maintaining performance, particularly in radio frequency applications, due to manufacturing difficulties and radiation losses associated with uneven interdigital transducer electrode pitches.
Innovation Solution
The implementation of a surface acoustic wave device with a piezoelectric substrate, an interdigital transducer electrode, and a temperature compensating layer comprising a silicon dioxide-titanium dioxide compound, which reduces temperature-dependent frequency drift and radiation losses, and includes an acoustic velocity adjustment structure to optimize acoustic wave propagation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the size of an acoustic wave filter is decreased, then the package size is reduced, but manufacturing precision and performance are compromised
Solution Approach 1:
The patent modifies the pitch of interdigital transducer electrodes from uniform to non-uniform distribution. Specifically, the pitch varies along the propagation direction of acoustic waves, with smaller pitch values near the center and larger pitch values toward the edges. This parameter change enables compact filter design while maintaining manufacturing feasibility and performance, as the non-uniform pitch compensates for edge effects and reduces radiation losses without requiring extremely tight manufacturing tolerances
Solution Approach 2:
The patent employs a temperature compensating layer composed of silicon dioxide-titanium dioxide compound material. This composite material provides both temperature compensation functionality and structural support, enabling the filter to maintain performance stability in compact dimensions. The specific composition (silicon dioxide with 90-99.99 wt% and titanium dioxide with 0.01-10 wt%) optimizes both mechanical properties for small size and thermal compensation for performance maintenance
2Ease of manufacture
If uniform interdigital transducer electrode pitch is used, then manufacturing is simplified, but radiation losses increase
Solution Approach 1:
The patent changes the pitch parameter of interdigital transducer electrodes from constant to variable along the acoustic wave propagation direction. The pitch is designed to be smaller at the center region and larger at the edge regions, which reduces acoustic energy radiation losses by better confining the acoustic field. This parameter modification maintains reasonable manufacturing complexity while significantly improving energy efficiency and filter performance
3Stability of the object's composition
If temperature compensating layer with titanium compound is added, then temperature stability is improved, but device complexity increases
Solution Approach 1:
The patent uses a composite dielectric material consisting of silicon dioxide and titanium dioxide compounds in the temperature compensating layer. This composite structure provides effective temperature compensation through the specific properties of titanium compound while maintaining compatibility with standard manufacturing processes. The layer is formed using conventional thin-film deposition techniques, and the material composition (0.1-10 wt% titanium compound) is optimized to achieve temperature stability without significantly increasing manufacturing complexity
Solution Approach 2:
The patent optimizes the thickness parameter of the temperature compensating layer to balance temperature compensation effectiveness and device complexity. The layer thickness is designed to provide sufficient temperature compensation while minimizing additional device complexity and manufacturing steps. This parameter optimization ensures that the temperature stability improvement is achieved with minimal increase in overall device 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
This configuration results in a compact acoustic wave filter with improved temperature stability and reduced radiation losses, achieving a balanced frequency response and out-of-band rejection, suitable for radio frequency applications.
Implementation Method 1
A surface acoustic wave resonator can include an interdigital transductor electrode on a piezoelectric substrate. The surface acoustic wave resonator can generate a surface acoustic wave on a surface of the piezoelectric layer on which the interdigital transductor electrode is disposed.
Implementation Method 2
The acoustic wave device also includes a temperature compensating layer disposed on the interdigital transducer electrode. The temperature compensating layer has a dielectric material including a titanium compound.
Data Source
AI summary
An acoustic wave device comprising a piezoelectric substrate with an interdigital transducer electrode disposed on the piezoelectric substrate and configured to excite an acoustic wave having a wavelength of λ. The device includes a temperature compensating layer disposed on the interdigital transducer electrode and having a dielectric material including a titanium compound.