Circular Piezoelectric Ladder Filter Resonator Arrangement
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Solution Overview
Problem
Ladder filters face challenges in further miniaturization due to the large spaces required between series and parallel arm resonators on a piezoelectric substrate, which limits the density of elastic wave resonators and overall device size reduction.
Innovation Solution
The configuration of series and parallel arm resonators on a single piezoelectric substrate includes first and second resonators electrically connected in parallel, with specific arrangements such as perpendicular orientation and intersecting width weighting, allowing for reduced dimensions and increased disposition density, and varying apodization ratios and capacitance to enhance filter characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If parallel arm resonators are disposed between series arm resonators to achieve miniaturization, then the filter size is reduced, but large spaces still remain between resonators preventing further miniaturization
Solution Approach 1:
The patent changes the arrangement dimension by disposing resonators in a circular pattern around a central through-hole on the piezoelectric substrate. This circular arrangement allows resonators to be positioned more compactly in radial directions rather than linear spacing, reducing the overall footprint while maintaining necessary separation between series and parallel arm resonators.
Solution Approach 2:
The patent utilizes the through-hole structure as a central element around which resonators are arranged. The resonators are positioned in annular regions between the through-hole and the substrate periphery, effectively nesting the resonator array within the space defined by the through-hole boundary, thereby maximizing space utilization.
2Reliability
If resonators are arranged with predetermined spacing to maintain performance, then filter characteristics are preserved, but the substrate area increases reducing miniaturization
Solution Approach 1:
By transitioning from linear/rectangular spacing to circular radial arrangement around a through-hole, the patent achieves more efficient space utilization. The resonators are distributed angularly around the circumference, allowing shorter arc-length distances while maintaining adequate separation, thus reducing substrate area while preserving filter characteristics.
Solution Approach 2:
The patent modifies the geometric parameters of resonator positioning by defining specific radial distances from the through-hole and angular separations between resonators. This parameter optimization allows compact arrangement while maintaining the electromagnetic coupling characteristics necessary for proper filter operation.
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 approach enables the miniaturization of ladder filters by reducing the space between resonators, allowing for a denser arrangement of elastic wave resonators and improved filter characteristics without compromising performance.
Implementation Method 1
a series arm resonator and a parallel arm resonator which include elastic wave resonators
Implementation Method 2
series arm resonators S1 to S3 and parallel arm resonators P1 and P2 on a piezoelectric substrate 2
Data Source
AI summary
A ladder filter including a series arm resonator and a parallel arm resonator disposed on the same common piezoelectric substrate achieves improved miniaturization. The ladder filter includes series arm resonators and parallel arm resonators, which include elastic wave resonators, and are disposed on the same common piezoelectric substrate, at least one parallel arm resonator of the series arm resonators and the parallel arm resonators includes a first resonator and a second resonator electrically connected in parallel to each other, and the first resonator and the second resonator are arranged in parallel or substantially in parallel in a direction perpendicular or substantially perpendicular to an elastic wave propagation direction, on one side outside one series arm resonator of remaining resonators in the elastic wave propagation direction thereof.