Acoustic Wave Filter Signal Layout for Lower Shared-Terminal Loss
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Solution Overview
Problem
Conventional acoustic wave filters that share output terminals suffer from increased insertion loss due to signal leakage between filter parts, which degrades their performance.
Innovation Solution
The design incorporates a specific arrangement of signal lines with three-dimensional intersections and inclined orientations to minimize electromagnetic coupling between signal lines, along with adjusted impedances for each filter part to suppress signal leakage and improve insertion loss characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If output terminals are shared among multiple acoustic wave filter parts, then the number of terminals is reduced and lines are simplified, but insertion loss deteriorates due to signal leakage between filter parts
Solution Approach 1:
The patent transitions from a two-dimensional planar layout to a three-dimensional configuration by making signal lines pass through different layers. Specifically, the fourth signal line is configured to three-dimensionally intersect with the second signal line, allowing both lines to share the same terminal while occupying different spatial dimensions, thereby reducing signal leakage and insertion loss while sharing terminals
Solution Approach 2:
The patent introduces an intermediary spatial arrangement between signal lines that share terminals. By configuring the fourth signal line to three-dimensionally intersect with the second signal line rather than running parallel or overlapping in the same plane, the patent creates a spatial mediator that prevents direct electromagnetic coupling while still allowing terminal sharing
2Ease of manufacture
If signal lines are arranged in a planar configuration connecting shared terminals, then device layout is simplified, but signal leakage occurs between lines with different potentials
Solution Approach 1:
The patent eliminates signal leakage by moving from a two-dimensional planar arrangement to a three-dimensional configuration. The fourth signal line is made to pass through a different layer or depth than the second signal line, creating a vertical or depth-based separation that prevents electromagnetic coupling while maintaining the simplified terminal sharing architecture
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 signal leakage and enhances the insertion loss and VSWR characteristics of the acoustic wave filter, maintaining performance even when output terminals are shared.
Implementation Method 1
a first acoustic wave filter part which has a plurality of first IDT electrodes which are arranged in a line, and generates an acoustic wave propagating in a first direction of a major surface of the substrate
Implementation Method 2
provision is made of a fourth signal line connecting the second IDT electrode and the first balanced signal terminal and having an intersection portion three-dimensionally intersecting with a part of the second signal line, in which this intersection portion extends in a direction inclined relative to the second signal line on the major surface of the substrate. Therefore, between signal lines having different potentials, leakage of a signal to another party is suppressed
Data Source
AI summary
An acoustic wave filter has a first signal line connecting one among the plurality of first IDT electrodes and the first balanced signal terminal; a second signal line connecting the other first IDT electrode with the second balanced signal terminal; a third signal line connecting one among the plurality of second IDT electrodes with the second balanced signal terminal; and a fourth signal line connecting the other second IDT electrode with the first balanced signal terminal. The fourth signal line has an intersection portion three-dimensionally intersecting with a part of the second signal line. The intersection portion extends in a direction inclined relative to the second signal line on the major surface.