Coil Device Magnetic Insulation for Filter Q Value
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Solution Overview
Problem
Magnetic coupling between coils in filter circuits and coil devices leads to reduced inductance and Q value, causing increased insertion loss and reduced attenuation, which affects the desired filter characteristics.
Innovation Solution
The design includes a coil device with a first coil connected in series and a second coil connected in parallel, where the first coil has a larger conductor area and a smaller coil opening than the second coil, minimizing the influence of magnetic flux and eddy currents, thereby maintaining a high Q value and reducing inductance loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple coils are magnetically coupled to achieve filter circuit functionality, then the filter circuit can be formed with series and parallel coil configurations, but the magnetic flux from one coil disturbs the other coil causing inductance reduction and eddy current loss
Solution Approach 1:
A magnetic insulating layer is introduced between the first and second coils to act as an intermediary that blocks magnetic flux from penetrating into the parallel coil. This prevents the series coil's magnetic flux from disturbing the parallel coil, thereby reducing eddy current loss while maintaining the magnetic coupling necessary for filter circuit operation
Solution Approach 2:
The magnetic field path is segmented by introducing the magnetic insulating layer that divides and isolates the magnetic flux of the series coil from the parallel coil. This segmentation prevents the harmful interaction between coils while allowing each coil to maintain its individual magnetic circuit
2Adaptability or versatility
If multiple coils are magnetically coupled to achieve filter circuit functionality, then the filter circuit can be formed with series and parallel coil configurations, but the magnetic flux disturbs the other coil causing inductance reduction
Solution Approach 1:
The magnetic insulating layer serves as a mediator that prevents magnetic flux from the series coil from penetrating into the parallel coil. This maintains the inductance of the parallel coil stable by blocking the disturbing magnetic flux while still allowing the necessary magnetic coupling for filter operation
Solution Approach 2:
The magnetic insulating layer is strategically placed only in the region where magnetic flux interference occurs between the series and parallel coils. This localized intervention maintains inductance stability where needed while preserving the overall magnetic coupling functionality of the filter circuit
3Reliability
If coil area is increased to maintain inductance, then inductance reduction is compensated, but the Q value is reduced and insertion loss increases
Solution Approach 1:
The magnetic insulating layer acts as a mediator that prevents magnetic flux from the series coil from inducing eddy currents in the parallel coil. This eliminates the need to increase coil area for compensation, thereby maintaining both inductance stability and high Q value with low insertion loss
4Adaptability or versatility
If magnetic coupling between coils is strengthened, then filter characteristics are enhanced, but eddy current loss increases causing Q value reduction
Solution Approach 1:
The magnetic insulating layer is introduced as an intermediary that selectively blocks the harmful component of magnetic flux (causing eddy currents) while allowing the useful magnetic coupling for filter characteristics to be maintained. This resolves the contradiction by preventing eddy current loss in the parallel coil
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 reduces or prevents the reduction in inductance and Q value, resulting in lower insertion loss and higher attenuation, achieving desired filter characteristics by maintaining a high Q value and minimizing heat loss.
Implementation Method 1
a first coil connected in series between the first terminal pair and the second terminal pair and including a first coil conductor wound around a winding axis, and a second coil connected in parallel between the first terminal pair and the second terminal pair, including a second coil conductor wound around the winding axis, and magnetically coupled to the first coil
Implementation Method 2
eddy current may occur in the other coil and the eddy current may cause eddy current loss to cause loss
Data Source
AI summary
A low pass filter includes a first terminal pair, a second terminal pair, a first coil connected in series between the first terminal pair and the second terminal pair and including a first coil conductor wound around a winding axis, and a second coil connected in parallel between the first terminal pair and the second terminal pair, including a second coil conductor wound around the winding axis, magnetically coupled to the first coil. An area of the first coil conductor is larger than an area of the second coil conductor.