Interdigital Elastic Wave Resonator Pitch Layout for Low Insertion Loss
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Solution Overview
Problem
Conventional elastic wave devices in mobile communication devices suffer from high insertion loss due to increased user demand and frequency band densification, requiring a more efficient design to maintain reliable operation.
Innovation Solution
The elastic wave device incorporates a comb-shaped electrode pair with interdigital and dummy electrode fingers on a piezoelectric substrate, where the pitch of electrode fingers changes along the direction perpendicular to the wave propagation, reducing energy loss by creating a velocity gradient that traps elastic waves within a guided-wave path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional elastic wave devices are used with uniform electrode pitch, then the device structure is simple, but insertion loss is high due to energy dispersion
Solution Approach 1:
The patent applies local quality by varying the pitch of interdigital electrode fingers in different regions of the comb-shaped electrodes. Specifically, the pitch is smaller in the center region and larger in the side regions, creating localized structural differences that trap elastic wave energy and reduce insertion loss while maintaining overall device functionality
Solution Approach 2:
The patent changes the geometric parameter of electrode pitch along the propagation direction. By gradually increasing the pitch from the center region toward the side regions, the elastic wave velocity is modulated to create a velocity gradient that confines energy within the guided-wave path, thereby reducing energy dispersion and insertion loss
2Productivity
If frequency band densification is implemented to accommodate more users, then communication capacity increases, but insertion loss increases reducing reliability
Solution Approach 1:
The patent modifies the electrode pitch parameter to create a velocity gradient that enhances energy trapping. This parameter change reduces insertion loss across the frequency band, ensuring reliable operation even when frequency bands are densified to increase communication capacity for more users
3Loss of energy
If uniform pitch electrodes are used, then manufacturing is simple, but energy trapping is insufficient leading to high insertion loss
Solution Approach 1:
The patent implements local quality by defining different pitch zones: a center region with smaller pitch for strong energy confinement and side regions with larger pitch for gradual velocity transition. This localized structural variation improves energy trapping while maintaining manufacturability through region-specific design rules
Solution Approach 2:
The electrode structure is segmented into distinct regions (center region and side regions) with different pitch characteristics. This segmentation allows independent optimization of each region's pitch parameters to achieve overall energy confinement while simplifying the manufacturing process through modular design
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 effectively reduces insertion loss by slowing down the wave velocity in side regions compared to the center region, enhancing the energy trapping and reducing energy dispersion, thereby improving the electrical characteristics of the elastic wave device.
Implementation Method 1
an elastic wave resonator which includes a comb-shaped electrode pair including a pair of com-shaped electrodes interdigitating with each other and provided on a piezoelectric substrate
Implementation Method 2
A pitch of the interdigital electrode fingers changes along a direction perpendicular to a propagation direction of elastic wave
Data Source
AI summary
An elastic wave device includes an elastic wave resonator which includes a comb-shaped electrode pair including a pair of com-shaped electrodes interdigitating with each other and provided on a piezoelectric substrate and which is configured to trap energy of the elastic wave therein. Each of the pair of comb-shaped electrodes includes interdigital electrode fingers connected to a common. A pitch of the interdigital electrode fingers changes along a direction perpendicular to a propagation direction of elastic wave. The elastic wave device has a small insertion loss and operates efficiently.