Elastic Wave Filter Ground Terminal Segmentation
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Solution Overview
Problem
Existing elastic wave filter devices face challenges in reducing size while maintaining attenuation outside the pass band, as sharing ground terminals between filters can lead to signal leakage and deterioration of attenuation characteristics.
Innovation Solution
The design includes a first and second elastic wave filter with different pass bands on a piezoelectric substrate, where reference terminals connected to parallel resonators are separated to prevent unnecessary signal paths, thereby reducing size without compromising attenuation outside the pass band.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If ground terminals for parallel resonators are shared over multiple filters to reduce size, then the device size is reduced, but signal leaks between filters and attenuation characteristics outside pass bands deteriorate
Solution Approach 1:
The patent divides the ground terminal connections into separate segments for each filter. Specifically, first and second ground terminals are provided separately, with the first ground terminal connected to parallel resonators of the first filter and the second ground terminal connected to parallel resonators of the second filter. This segmentation prevents signal leakage between filters while maintaining compact size by limiting the separation to only what is necessary for electrical isolation.
2Area of stationary object
If all ground terminals are shared to maximize size reduction, then the device area is minimized, but unnecessary signal paths are created causing signal leakage
Solution Approach 1:
The patent extracts the ground terminal connections from a fully shared configuration and separates them into distinct first and second ground terminals. This extraction removes the harmful unnecessary signal paths that would exist in a fully shared ground configuration, while still achieving area reduction by having only two ground terminals instead of multiple separate ones.
3Reliability
If reference terminals are separated to prevent signal leakage, then attenuation outside pass band is maintained, but device complexity increases
Solution Approach 1:
The patent applies local quality by providing separation specifically for the ground terminals that are critical for preventing signal leakage, while other terminals can remain shared or connected. This targeted approach maintains attenuation characteristics without unnecessarily increasing overall device complexity, as the separation is applied only where it is most needed for electrical isolation.
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 effectively reduces the size of the elastic wave filter device while ensuring adequate attenuation outside the pass band, preventing signal leakage and maintaining high-frequency signal integrity.
Implementation Method 1
a first elastic wave filter and a second elastic wave filter having pass bands that are different from each other and provided on a piezoelectric substrate
Data Source
AI summary
An elastic wave filter device includes first and second reception filters, an input terminal, output terminals, and reference terminals provided on a piezoelectric substrate. The first reception filter includes series resonators and parallel resonators, and the second reception filter includes series resonators and parallel resonators. The reference terminal connected to the parallel resonator connected so as to be closest to the output terminal among the parallel resonators included in the first reception filter, and the reference terminal connected to the parallel resonator connected so as to be closest to the output terminal among the parallel resonators included in the second reception filter, are separated from each other on the piezoelectric substrate.