Figure-8 Inductor with Center Feed Lines for Magnetic Field Cancellation
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Solution Overview
Problem
Existing inductor designs for voltage controlled oscillators (VCOs) suffer from significant magnetic field interference with surrounding circuitry due to incomplete cancellation of magnetic field components, leading to disturbances in operation.
Innovation Solution
The design features two identical loops in a figure-of-8 arrangement with feed lines extending through the area circumscribed by one loop and connected at the center, ensuring symmetry about two axes, which enhances the cancellation of magnetic field components at distance, particularly along the axis bisecting the structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a figure-of-8 inductor configuration is used, then magnetic field cancellation is improved, but complete cancellation is not achieved due to asymmetry and feed line contributions
Solution Approach 1:
The inductor is divided into two separate loops (first loop and second loop) that are positioned symmetrically about a first axis. Each loop is independently configured with precise geometric parameters to ensure that their magnetic field contributions cancel each other at distance. The segmentation allows for optimized current distribution and magnetic field control in each loop while maintaining overall symmetry.
Solution Approach 2:
The feed lines are configured asymmetrically with respect to the loops they connect to. Specifically, the first feed line connects to the first loop at a first attachment point, and the second feed line connects to the second loop at a second attachment point, where the distance from the first axis to the first attachment point differs from the distance from the first axis to the second attachment point. This asymmetric configuration compensates for the magnetic field contributions from the feed lines themselves, enabling complete cancellation.
2Ease of operation
If feed lines are connected to loop ends, then current flow is simplified, but magnetic field cancellation is compromised due to skewed fields from close coupling
Solution Approach 1:
The feed lines are positioned to extend through the area circumscribed by the opposite loop rather than connecting at the loop ends. The first feed line extends through the area circumscribed by the second loop, and the second feed line extends through the area circumscribed by the first loop. This local quality differentiation optimizes the magnetic field distribution and reduces coupling effects between the feed lines and loops, enabling complete cancellation while maintaining ease of current flow.
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 configuration achieves substantial cancellation of magnetic field components at distance, reducing interference with surrounding circuitry and improving the symmetry of magnetic field matching between loops, thereby minimizing disturbances.
Implementation Method 1
the magnetic field created by the current flowing clockwise around the lower loop is directed into the page and the magnetic field created by the current flowing anticlockwise around the upper loop is directed out of the page. The field lines join such that most of the magnetic field components in the plane of the inductor are contained within the area of the figure-of-8 structure. A degree of cancellation of the magnetic field components is therefore achieved at distance from the inductor in the plane of the inductor.
Data Source
Figure 1
Figure 2
Figure 3a
AI summary
An inductor structure comprising: a first loop (301) and a second loop (302); a first feed line connected to a first end (303) of the first loop at the centre of the inductor structure and a second feed line connected to a first end (306) of the second loop at the centre of the inductor structure, each of the first and second feed lines extending out of the plane of the inductor structure; and a crossover section adjacent to the first end of the first loop and the first end of the second loop, the crossover section coupling the first loop to the second loop so as to cause current flowing from the first feed line to the second feed line to circulate around the first loop in a first rotational direction and around the second loop in a second rotational direction opposite to the first rotational direction.