Combined Via Structure for Compact Multilayer Filters
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Solution Overview
Problem
Existing multilayer board technologies face challenges in achieving compact, cost-effective filtering components with improved passband and stopband sharpness, particularly due to parasitic coupling and large dimensions in distributed-element devices.
Innovation Solution
A combined via structure is introduced, comprising two working parts with signal and ground vias connected to ground planes, where the first part uses clearance holes for low-loss signal transmission and the second part employs corrugated plates with isolating slits to control characteristic impedance and propagation constant, reducing transverse dimensions and enhancing resonant frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If distributed-element filters are designed using planar transmission line segments, then the filters can be implemented in multilayer boards, but parasitic coupling and unwanted radiation occur leading to large dimensions and reduced performance
Solution Approach 1:
The patent transitions from planar transmission line segments to three-dimensional via structures with conductive plates extending in the vertical dimension. This dimensional change enables better control over electromagnetic fields, reducing parasitic coupling and radiation while maintaining multilayer board manufacturability
Solution Approach 2:
The patent modifies the characteristic impedance and propagation constant by changing the geometry parameters of the via structures, including the dimensions of conductive plates, spacing between vias, and plate thickness. These parameter changes optimize performance while reducing the harmful effects of parasitic coupling
2Volume of moving object
If the dimensions of filtering structures in multilayer boards are reduced, then compactness is improved, but control over characteristic impedance and propagation constant becomes more difficult
Solution Approach 1:
The patent applies different geometric configurations to different parts of the via structure. Conductive plates with specific dimensions and patterns are placed at strategic locations within the via structure, allowing localized control over electromagnetic properties while maintaining overall compact dimensions
Solution Approach 2:
The patent combines multiple functional elements (signal vias, ground vias, conductive plates, and dielectric materials) into a composite via structure. This composite approach enables simultaneous control over characteristic impedance, propagation constant, and physical dimensions through the synergistic interaction of different components
3Measurement precision
If sharpness of passband and stopband is improved to satisfy system requirements, then filtering performance is enhanced, but device complexity and dimensions increase
Solution Approach 1:
The patent uses three-dimensional via structures with vertically extending conductive plates to achieve sharp filtering characteristics. The vertical dimension provides additional degrees of freedom for controlling resonance frequencies and Q-factor, enabling sharp passband and stopband without increasing planar footprint or overall device complexity
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
The proposed solution enables the creation of compact filters with improved passband and stopband sharpness, reducing overall filter dimensions and enhancing performance, as demonstrated by simulated return and insertion losses.
Implementation Method 1
This working part is applied to obtain short-circuited or open-circuited resonance stub in a multilayer board
Implementation Method 2
parasitic coupling, unwanted radiation and large enough dimensions can be those issues, which can arise at development of distributed-element devices
Data Source
AI summary
A filter is provided with a planar transmission line and a combined via structure connected to (both) one ends of the planar transmission line. The planar transmission line and the combined via structure are disposed in a same multilayer board. The combined via structure comprises two working parts. The first working part comprises a segment of signal via and a plurality of segments of ground vias surrounding the signal via. The second working part comprises a segment of the same signal via, a plurality of segments of the same ground vias, smooth conductive plate and corrugated conductive plate. The smooth conductive plate and the corrugated conductive plate are connected to the signal via. The second working part comprises a segment of the same signal via, a plurality of segments of the same ground vias and corrugated conductive plate. The corrugated conductive plate is connected to the signal via.