Variable Inductor with Serpentine Coils and Magnetic Coupling Control
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Solution Overview
Problem
Integrated circuits with inductors face performance deterioration due to eddy currents generated in conductor or semiconductor materials, complicating production and requiring magnetic isolation, which increases manufacturing complexity.
Innovation Solution
The use of serpentine coils arranged above each other with a dielectric layer in between, and a control circuit with switches to adjust the magnetic coupling coefficient, allowing for variable inductance values while minimizing eddy current generation and avoiding the need for a ground plane.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a ground plane is introduced to magnetically isolate the coils from the conductor or semiconductor layer, then eddy current generation is reduced, but manufacturing complexity increases
Solution Approach 1:
The patent extracts and removes the ground plane from the structure, replacing it with serpentine coils that inherently reduce eddy current generation through their geometry. The harmful element (ground plane) is taken out while the useful function (eddy current reduction) is achieved through the serpentine coil design itself
Solution Approach 2:
The patent uses serpentine (curved) coil geometries instead of straight or circular loops. The serpentine shape distributes the magnetic field more evenly and reduces concentrated eddy currents in the substrate, achieving eddy current reduction without requiring additional isolation layers
2Object-affected harmful factors
If the ground plane is placed close to the coils to reduce eddy currents, then eddy current generation is limited, but capacitive coupling between the ground plane and coils increases
Solution Approach 1:
The ground plane is completely removed from the structure. Instead of positioning it at an optimal distance, the patent eliminates it entirely and uses the serpentine coil geometry to achieve eddy current reduction, thereby avoiding the capacitive coupling problem entirely
3Ease of manufacture
If loop or spiral coils are used in metallization layers, then inductors can be formed in integrated circuits, but eddy currents are generated in the conductor or semiconductor material deteriorating performance
Solution Approach 1:
The patent transforms the traditional loop or spiral coil geometry into a serpentine (sinuous) shape. This curved, back-and-forth geometry distributes the magnetic field lines more uniformly through the substrate, reducing concentrated eddy currents while maintaining the planar integrated circuit fabrication compatibility
Solution Approach 2:
The patent changes the geometric parameters of the coils from closed loops or spirals to open serpentine traces. This parameter change in coil geometry fundamentally alters the magnetic field distribution, reducing eddy current induction in the substrate while maintaining ease of manufacturing
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 approach simplifies manufacturing, reduces eddy current generation, and enables a wide range of inductance values, from very low to high, without compromising performance, by effectively managing the magnetic coupling between coils.
Implementation Method 1
an inductor comprising first and second coils which are magnetically coupled together, this magnetic coupling resulting in the formation of a mutual inductance M between these two coils when the inductor is energized
Implementation Method 2
when the inductor is energized, the coils generate eddy currents in this conductor or semiconductor material, this resulting in a deterioration in the performance of the inductor
Data Source
AI summary
This integrated circuit comprises an inductor formed by at least a first coil and a second coil which are magnetically coupled together. Each of the first and second coils comprises a metal line which extends continuously, in a plane, between a first end and second end, said metal line following a winding path around an axis of the coil parallel to the plane, this metal line comprising for this purpose a succession of sections which each intersect the axis of the coil, and the sections of this succession are electrically connected in series with each other.