Segmented Shielding Structure for Integrated Inductor Substrate Losses
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Solution Overview
Problem
Integrated inductors and transformers on silicon substrates suffer from substrate losses due to electromagnetic coupling, leading to a dropped Q factor, and traditional solid shielding structures can cause Eddy current effects that damage these components.
Innovation Solution
A shielding structure comprising conductive units with odd-numbered second conductive portions that progressively diminish in length, connected through via holes and a grounding portion, which reduces the Eddy current effect by creating openings and minimizing current flow, while the multi-layer design optimizes performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a solid shielding structure is used to prevent substrate losses, then electromagnetic coupling is reduced, but Eddy current effects increase causing reverse magnetic fields that damage inductors/transformers
Solution Approach 1:
The shielding structure is divided into multiple discrete conductive units (first through fourth conductive units) with conductive portions arranged in specific patterns, rather than using a continuous solid shield. This segmentation disrupts the formation of large Eddy currents while maintaining electromagnetic shielding effectiveness.
Solution Approach 2:
Different regions of the shielding structure have different conductive properties - some areas have conductive portions while others have openings. The conductive units are strategically positioned to provide shielding where needed while creating non-conductive paths to minimize Eddy currents in critical regions.
2Loss of energy
If the silicon substrate has high resistance to prevent coupling currents, then substrate losses are reduced, but this is difficult to achieve as typical silicon substrate resistance is only 10-15 Ohm-Cm
Solution Approach 1:
The shielding structure acts as an intermediary element between the inductor/transformer and the silicon substrate. Instead of trying to modify the substrate's inherent resistance properties, the shield provides the necessary electromagnetic isolation while allowing the substrate to maintain its normal electrical characteristics.
3Object-affected harmful factors
If a continuous shielding structure is used to block electromagnetic energy, then shielding effectiveness is improved, but the structure complexity and potential for Eddy currents increase
Solution Approach 1:
The shield is segmented into multiple conductive units with specific patterns of conductive portions and openings. This segmentation achieves effective electromagnetic shielding through distributed reflection and absorption while reducing Eddy current paths, and can be implemented using standard multi-layer PCB techniques.
Solution Approach 2:
The shielding effect is achieved through the two-dimensional arrangement of conductive portions within the planar structure. The pattern of conductive units and openings creates electromagnetic shielding in the vertical dimension through distributed reflection and absorption, without requiring a three-dimensional solid structure.
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 shielding structure effectively minimizes the reverse magnetic field induced by current, enhancing the characteristics of integrated inductors and transformers by reducing substrate losses and Eddy current effects, and allows for fine-tuning of resistances to optimize performance.
Implementation Method 1
the solid shielding structure may cause a large Eddy current effect. In this case, a reverse magnetic field is generated when the current is flowing through the shielding structure
Implementation Method 2
when the entire integrated circuit is working the silicon substrate may be coupled with a generated electromagnetic energy, which causes substrate losses
Data Source
AI summary
Disclosed is a shielding structure for an integrated inductor/transformer, configured under the integrated inductor or the transformer and upon a substrate. The shielding structure includes conductive units, first connecting portions, via holes, a second connecting portion and a grounding portion. Each conductive unit includes a first conductive portion and second conductive portions extending from the first conductive portion. The number of the second conductive portions is odd. The length of each second conductive portion progressively diminishes from a center of the first conductive portion to both of two ends of the first conductive portion. The first connecting portion connects the first conductive portions of the conductive units through via holes. The grounding portion is connected to one of the first conductive portions. The second connecting portion connects all longest second conductive portions together. Moreover, the conductive units and the second connecting portion are made of different conductive materials.