Surface Acoustic Wave Device With Insulating Film Intersections
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Solution Overview
Problem
Conventional surface acoustic wave filters with balanced-to-unbalanced conversion function face issues of high insertion loss in the passband and complex package configurations, leading to deteriorated balancing between balanced signal terminals and limited compatibility with other filter configurations.
Innovation Solution
The design includes a surface acoustic wave device with cascade-connected elements where signal lines intersect through an insulating film, reducing stray capacitance and allowing for a common package configuration by minimizing the space between surface acoustic wave elements and eliminating pads between them, thereby improving balancing and reducing insertion loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If signal lines are disposed to connect cascade-connected filters with ground pad between stages, then filters can be connected, but insertion loss in the passband increases due to large stray capacitance between wiring and ground pad
Solution Approach 1:
The patent applies three-dimensional wiring structure where signal lines pass through insulating films to cross ground pads in different layers. This vertical stacking approach transforms the two-dimensional planar layout into a three-dimensional structure, allowing signal lines to bypass the ground pad area and reducing parasitic capacitance coupling between signal and ground paths.
Solution Approach 2:
The patent introduces insulating films as intermediary layers between signal lines and ground pads. These insulating films act as mediators that electrically isolate the signal paths from ground references, minimizing unwanted capacitive coupling while still allowing the ground pads to serve their grounding function.
2Reliability
If ground pad is disposed between cascade-connected filters, then filtering function is achieved, but balancing between balanced signal terminals deteriorates
Solution Approach 1:
The patent uses multi-layer wiring structures where signal lines for balanced terminals are routed through different insulating film layers. This vertical separation ensures that both balanced signal paths have equal length and symmetrical routing, maintaining proper balancing while allowing ground pads to be positioned optimally for filtering performance.
3Adaptability or versatility
If complex package configuration is used for balanced-to-unbalanced conversion, then conversion function is achieved, but compatibility with other filter configurations is limited
Solution Approach 1:
The patent designs a universal substrate structure with standardized terminal arrangements and multi-layer wiring that can accommodate different filter configurations. The same substrate and wiring architecture can support both balanced-to-unbalanced conversion filters and other filter types, eliminating the need for specialized package designs for each filter configuration.
4Ease of manufacture
If pads are disposed between cascade-connected surface acoustic wave elements, then elements can be connected, but space between elements increases leading to higher insertion loss
Solution Approach 1:
The patent merges the connection function previously performed by discrete pads into the insulating film structure itself. The insulating films serve dual purposes: providing electrical isolation and enabling direct routing of signal lines between cascade-connected elements, thereby eliminating the need for separate pad structures and reducing the space between elements.
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 significantly reduces insertion loss in the passband and enhances balancing between balanced signal terminals, enabling the use of a common package for different filter configurations, thus improving the overall performance and versatility of the surface acoustic wave device.
Implementation Method 1
different signal lines connected to the same surface acoustic wave element intersect through an insulating film
Implementation Method 2
a surface acoustic wave element disposed between the unbalanced terminal and the balanced terminals on the substrate
Data Source
AI summary
A surface acoustic wave device includes a substrate, a plurality of terminals including at least an unbalanced terminal and balanced terminals, and at least one of surface acoustic wave element disposed between the unbalanced terminal and the two balanced terminals. Different signal lines connected to the same surface acoustic wave element intersect through insulating films.