Asymmetric Busbar Layout in Acoustic Wave Devices for Spurious Mode Control
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Solution Overview
Problem
Surface acoustic wave (SAW) devices suffer from energy leakage due to spurious modes, leading to a decrease in quality factor, and face challenges in reducing size and noise.
Innovation Solution
The acoustic wave device incorporates a busbar segment with two different dimensions, along with finger electrodes, to enhance energy transmission and reduce spurious modes, thereby improving the quality factor and allowing for smaller device sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional busbar segments with uniform dimensions are used, then the device structure is simple, but energy leakage occurs due to spurious modes resulting in decreased quality factor
Solution Approach 1:
The busbar segment is designed with different dimensions at different locations: a first dimension at the first end and a second dimension at the second end, where the first dimension is greater than the second dimension. This local variation in geometry suppresses spurious modes and reduces energy leakage without requiring complete structural redesign throughout the entire device.
Solution Approach 2:
The busbar segment employs asymmetric dimensions where the first end has a larger cross-sectional dimension than the second end. This asymmetric configuration creates an impedance gradient that prevents standing waves and spurious modes, thereby reducing energy leakage while maintaining structural simplicity.
2Volume of moving object
If the size of acoustic wave devices is reduced, then compactness is improved, but noise reduction and quality factor maintenance become more challenging
Solution Approach 1:
The busbar segment dimensions are specifically optimized with the first dimension greater than the second dimension, creating a tapered structure that suppresses spurious modes. This parameter optimization allows compact device design while maintaining high quality factor and reducing noise through inherent acoustic wave control.
Data Source
AI summary
An acoustic wave device includes a first busbar segment, and two finger electrodes. The first busbar segment is disposed along a first direction. The first finger electrode extends in parallel to a second direction from a first terminal to a second terminal, and the first terminal thereof contacts the first busbar segment. The second finger electrode extends in parallel to the second direction from a first terminal to a second terminal, and the first terminal thereof contacts the first busbar segment. The second finger electrode is disposed to be separated from the first finger electrode. The first busbar segment has a first dimension and a second dimension both measured in parallel to the second direction. The first dimension is located corresponding to the first finger electrode, the second dimension is located corresponding to the second finger electrode, and the first dimension is different from the second dimension.