Inductor Current Return Reduces Coupling
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Solution Overview
Problem
In semiconductor integrated circuits, inductive coupling between devices reduces the performance of inductors due to unpredictable electrical interactions, making it challenging to maintain intended inductance values and quality factors (Q) as device density increases.
Innovation Solution
An inductor structure with a current return formed from interconnected metal layers, where the current return surrounds the coil and is connected to it via a connector, ensuring a predefined current path with lower impedance, thereby reducing electromagnetic coupling and stabilizing the inductance and quality factor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If inductors are placed closer together to increase device density, then productivity increases, but inductive coupling between devices increases causing performance degradation
Solution Approach 1:
A current return path is introduced as an intermediary element between the inductor and ground. This current return acts as a mediator that provides a controlled, low-impedance path for return currents, thereby reducing unpredictable inductive coupling effects between adjacent inductors while allowing higher device density
2Device complexity
If traditional inductor structures are used without defined current return paths, then device complexity is reduced, but inductance stability and quality factor deteriorate due to unpredictable electrical interactions
Solution Approach 1:
The current return path is pre-defined and established as part of the inductor structure design. By preliminarily establishing the return current path before the inductor operates, the electrical interactions are controlled and predictable, ensuring stable inductance and quality factor without requiring complex additional components
3Object-affected harmful factors
If guard rings and metal fences are used to reduce electromagnetic coupling, then inductive coupling is reduced, but device complexity and manufacturing complexity increase
Solution Approach 1:
The harmful inductive coupling effects are extracted and redirected through a dedicated current return path. Instead of using complex guard rings and metal fences to block or shield electromagnetic fields, the solution extracts the return current and channels it through a defined low-impedance path, simplifying the overall structure while maintaining effectiveness
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 inductor structure reduces inductive coupling with other IC structures, stabilizes inductance, and improves the quality factor (Q) by ensuring current flow through the current return, allowing for closer placement of inductor structures within the IC.
Implementation Method 1
One example of an electrical interaction is inductive coupling. Inductive coupling can reduce the performance of devices and, in particular, inductors, implemented within an IC.
Implementation Method 2
The inductor structure further includes a connector connecting the coil and the current return wherein the connector connects a midpoint of the coil to the current return
Data Source
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AI summary
An inductor structure implemented within a semiconductor integrated circuit (IC) includes a coil (105) of conductive material including at least one turn and a current return (130, 500) encompassing the coil. The current return is formed of a plurality of interconnected metal layers (510, 515, 520, 525) of the semiconductor integrated circuit.