Co-Optimized Acoustic Mirror Structure for Longitudinal and Shear Reflection
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Solution Overview
Problem
Acoustic wave resonators in wireless devices suffer from significant energy loss due to the inefficient reflection of both longitudinal and shear waves, which limits their energy efficiency in radio-frequency filtering.
Innovation Solution
The design of an acoustic device with a co-optimized acoustic mirror that includes alternating layers of higher and lower impedance materials, where the second higher impedance layer has a greater thickness than the first, to effectively reflect both longitudinal and shear waves, reducing energy loss and enhancing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If acoustic mirrors are designed to primarily reflect longitudinal waves, then longitudinal wave reflection is improved, but shear wave reflection deteriorates, resulting in significant energy loss
Solution Approach 1:
The patent applies parameter changes by adjusting the thickness of higher impedance layers in the acoustic mirror to different values (first thickness for longitudinal waves, second greater thickness for shear waves) to optimize reflection for both wave types simultaneously, thereby reducing energy loss while maintaining adaptability to different wave modes
Solution Approach 2:
The patent uses composite materials by combining multiple layers of different impedance materials (higher impedance and lower impedance layers) with specific thicknesses to create an acoustic mirror that can reflect both longitudinal and shear waves effectively, solving the contradiction between optimizing for one wave type versus another
2Loss of energy
If acoustic mirrors use uniform layer thickness, then manufacturing simplicity is improved, but reflection efficiency for both longitudinal and shear waves deteriorates
Solution Approach 1:
The patent applies local quality by making different portions of the acoustic mirror structure have different thicknesses (first higher impedance layer with first thickness, second higher impedance layer with second thickness greater than first) to locally optimize reflection properties for different wave types, achieving better overall energy efficiency despite increased structural 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 design significantly reduces energy losses by optimizing the reflection of both wave types, thereby improving the energy efficiency of acoustic wave devices used in radio-frequency filters.
Implementation Method 1
an acoustic mirror including at least one higher impedance layer co-optimized for reflecting longitudinal waves and shear waves corresponding to a target operating frequency. The acoustic mirror includes lower acoustic impedance layers (lower impedance layers) and at least one higher acoustic impedance layer (higher impedance layer).
Implementation Method 2
Acoustic resonators include electrodes on a piezoelectric material to convert electromagnetic waves into acoustic waves, filter the acoustic waves, and convert the filtered waves back into electromagnetic waves.
Data Source
AI summary
An acoustic device includes a piezoelectric layer between a first, bottom electrode and a second, top electrode, and an acoustic mirror optimized for reflecting longitudinal waves and shear waves at a target operating frequency. The acoustic mirror includes lower acoustic impedance layers and at least one higher acoustic impedance layer. In an example, layers of the acoustic mirror alternate between lower impedance and higher impedance, with a first lower acoustic impedance layer adjacent to the bottom electrode, and a first higher acoustic impedance layer having a greater thickness than a second higher acoustic impedance layer. In another example, the acoustic mirror has a higher acoustic impedance layer with a thickness corresponding to at least half of a wavelength of the target operating frequency in the higher acoustic impedance layer. An acoustic device with an acoustic mirror optimized for both longitudinal waves and shear waves reduces energy losses for increased efficiency.