Multilayer Filter Via Assembly for Low Parasitic Inductance
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Solution Overview
Problem
Current high-frequency filters, such as those used in 5G spectrum frequencies, face challenges in customizing performance characteristics due to parasitic inductance introduced by vertical structures like vias, which affect their performance at high frequencies.
Innovation Solution
A multilayer filter design incorporating a via assembly with a specific area-to-squared-length ratio greater than 3.25, which minimizes parasitic inductance and allows for precise control over inductance values, enabling better performance characteristics at high frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional via structures are used in multilayer filters, then vertical electrical connections are achieved, but parasitic inductance increases and performance characteristics deteriorate at high frequencies
Solution Approach 1:
The patent changes the geometric parameters of the via assembly by optimizing the area-to-squared-length ratio to be greater than 3.25, which fundamentally alters the electrical characteristics and reduces parasitic inductance. This parameter optimization enables the via assembly to maintain low inductance while providing necessary vertical electrical connections in the multilayer filter structure.
Solution Approach 2:
The patent transitions from considering only the vertical dimension (length) of vias to incorporating the cross-sectional area dimension, creating an area-to-squared-length ratio metric. This dimensional approach allows for optimizing both the vertical connection length and the horizontal cross-sectional area simultaneously, achieving low inductance through balanced dimensional design rather than merely minimizing via length.
2Reliability
If via assemblies with optimized area-to-squared-length ratio are used, then parasitic inductance is reduced and frequency performance is improved, but manufacturing precision requirements increase
Solution Approach 1:
By establishing the area-to-squared-length ratio as a critical design parameter with a specific threshold (>3.25), the patent provides manufacturers with a clear target specification. This parameter-focused approach simplifies the manufacturing process by concentrating optimization efforts on achieving the ratio threshold rather than independently optimizing multiple via dimensions, thereby reducing the overall manufacturing precision burden.
Solution Approach 2:
The patent performs preliminary design optimization by calculating and specifying the required area-to-squared-length ratio before manufacturing begins. This pre-determined parameter guides the manufacturing process, allowing manufacturers to plan via dimensions and spacing in advance to meet the ratio requirement, rather than requiring complex post-manufacturing adjustments or inspections.
3Reliability
If conventional waveguide or cavity designs are used, then high frequency filtering is achieved, but performance characteristics are difficult to tailor or customize
Solution Approach 1:
The patent enables performance customization by allowing independent adjustment of via assembly parameters (cross-sectional area, length, spacing, and arrangement) to achieve the target area-to-squared-length ratio. Different via configurations can be selected to tailor the inductance values and frequency response characteristics of the filter, providing design flexibility that fixed waveguide or cavity structures cannot offer.
Solution Approach 2:
The patent divides the filter structure into modular via assemblies that can be independently designed and positioned within the multilayer structure. Each via assembly can be optimized with specific geometric parameters, and multiple via assemblies can be arranged in different patterns (e.g., staggered, grid, or irregular arrangements) to achieve customized filtering characteristics for different frequency bands and application requirements.
Data Source
AI summary
A multilayer filter may include a dielectric layer having a top surface, a bottom surface, and a thickness in a Z-direction between the top surface and the bottom surface. The multilayer filter may include a conductive layer formed on the top surface of the dielectric layer. The multilayer filter may include a via assembly formed in the dielectric layer and connected to the conductive layer on the top surface of the dielectric layer. The via assembly may extend to the bottom surface of the dielectric layer. The via assembly may have a length in the Z-direction and a total cross-sectional area in an X-Y plane that is perpendicular to the Z-direction. The via assembly may have an area-to-squared-length ratio that is greater than about 3.25.