Multiplexer Resonator Overlap for Size and Isolation
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Solution Overview
Problem
Existing multiplexer designs face challenges in achieving good isolation characteristics when filters are arranged to overlap, leading to interference, and when they are not overlapping, size reduction is difficult.
Innovation Solution
A multiplexer design where at least part of one filter's resonators overlap with corresponding parts of the other filter's resonators in plan view, while keeping other resonators non-overlapping to minimize interference and allow for size reduction, utilizing a ladder-type filter structure with series and parallel resonators connected between common and terminal terminals across an air gap.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If filters are arranged to overlap in plan view, then the overall size of the multiplexer is reduced, but isolation characteristics deteriorate due to interference between resonators
Solution Approach 1:
The patent segments the resonators into different groups based on their overlapping status. Specifically, it divides resonators into: (1) resonators that overlap in plan view (reducing size), (2) resonators that do not overlap (maintaining isolation). This segmentation allows selective application of overlapping strategy to different resonator pairs, resolving the contradiction between size reduction and isolation maintenance.
Solution Approach 2:
The patent applies different spatial arrangements to different local regions of the filter structure. Instead of uniformly overlapping or non-overlapping all resonators, it selectively overlaps only certain resonators (e.g., series resonators in specific positions) while keeping others non-overlapping. This local differentiation optimizes both size and isolation characteristics in their respective regions.
2Reliability
If filters are arranged not to overlap in plan view, then isolation characteristics are maintained, but size reduction becomes difficult
Solution Approach 1:
The patent utilizes the third dimension (vertical stacking with air gap) to resolve the two-dimensional planar conflict. By arranging resonators to overlap in plan view while separating them vertically with an air gap, the design achieves size reduction in the horizontal plane without compromising isolation, as the vertical separation prevents interference. This dimensional transition allows both overlapping benefits and isolation requirements to be satisfied simultaneously.
Data Source
AI summary
A multiplexer includes: first and second substrate respectively having first and second surfaces facing each other across an air gap; a first filter including first resonators located on the first surface and connected between a common terminal and a first terminal; a second filter including second resonators located on the second surface and connected between the common terminal and a second terminal, a first resonator connected in series between the common terminal and the first terminal and closest to the common terminal overlapping with a second resonator connected in series between the common terminal and the second terminal and closest to the common terminal, first resonators other than the first resonator closest to the common terminal not overlapping with the second resonators, second resonators other than the second resonator closest to the common terminal not overlapping with the first resonators.