Multi-Band Filter Layout for Isolation and Low Insertion Loss
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Solution Overview
Problem
In multi-band wireless terminals, arranging filters with different frequency bands on the same substrate leads to signal interference, resulting in inadequate isolation and deterioration of insertion loss characteristics.
Innovation Solution
The filters are arranged such that the proximity filter and non-proximity filter terminals are not adjacent, with the non-proximity filter often placed between the proximity filter and the second filter, and a ground terminal is strategically omitted between certain terminals to minimize interference while maintaining device size reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If filters with different frequency bands are arranged on the same substrate, then the device size is reduced, but signal interference occurs and insertion loss characteristics deteriorate
Solution Approach 1:
The patent segments the filter arrangement by identifying proximity filters (first and third filters) and non-proximity filters (second filter), and selectively positioning ground terminals between specific filter groups to address interference in different frequency band configurations
Solution Approach 2:
The patent introduces ground terminals as intermediary elements between filters to shield and isolate signals. The ground terminals act as mediators that prevent harmful electromagnetic coupling between proximity filters while maintaining compact device dimensions
2Volume of moving object
If filters are arranged adjacent to each other on the same substrate, then the device size is minimized, but isolation between filter lines is insufficient
Solution Approach 1:
The patent applies local quality by providing ground terminals only between specific filter groups (proximity filters) where interference occurs, rather than uniformly between all filters. This targeted approach maintains isolation where needed while minimizing device size
3Object-generated harmful factors
If ground terminals are disposed between all filter terminals, then signal interference is reduced, but device complexity and size increase
Solution Approach 1:
The patent segments the ground terminal arrangement by identifying which filter groups require isolation (proximity filters with overlapping or adjacent frequency bands) and placing ground terminals only between those specific groups, reducing overall device complexity
Solution Approach 2:
The patent changes the parameter of ground terminal placement from a uniform arrangement to a selective arrangement based on frequency band proximity, thereby reducing device complexity while maintaining interference mitigation
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 reduces signal interference and maintains effective isolation between filters, preventing deterioration in insertion loss characteristics and achieving the goal of miniaturizing the filter device.
Implementation Method 1
each of the first to third filters is a surface acoustic wave filter
Data Source
AI summary
A filter device includes a substrate and first to third filters provided on the substrate and each including an input terminal and an output terminal. A center frequency of a pass band of the first filter is lower than a center frequency of a pass band of the second filter, and the center frequency of the pass band of the second filter is lower than a center frequency of a pass band of the third filter. Of the first and third filters, when the filter having the center frequency of the pass band close to the center frequency of the filter is defined as a proximity filter and the other is defined as a non-proximity filter, an input terminal and an output terminal of the proximity filter are not adjacent to an input terminal and an output terminal of the second filter.