Spiral Winding Common Mode Choke on Circuit Board
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Solution Overview
Problem
Conventional common mode chokes face challenges in effectively suppressing common mode noise, especially at high frequencies, due to frequency-dependent permeability of magnetic cores, which increases insertion loss for differential mode signals and reduces common mode noise suppression.
Innovation Solution
A circuit board module with a common mode choke structure formed by conducting lines with spiral winding segments, where the mutual inductance coupling coefficient between adjacent spiral winding segments is greater than 0.3, allowing for effective common mode noise suppression without using ferromagnetic materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ferromagnetic materials are used in the magnetic core to enhance mutual inductance, then insertion loss for differential mode signal is reduced, but at high frequencies the permeability decreases causing insertion loss to increase and common mode noise suppression to decrease
Solution Approach 1:
The patent removes the ferromagnetic material from the common mode choke structure, extracting the problematic frequency-dependent permeability characteristic while retaining the essential mutual inductance function through air-core spiral windings. This eliminates the high-frequency performance degradation caused by ferromagnetic material limitations.
Solution Approach 2:
The patent changes the fundamental parameter of magnetic permeability from high (ferromagnetic) to low (air core), and compensates by optimizing the geometric parameters of the spiral windings (number of turns, winding density, spacing) to achieve the required mutual inductance without frequency-dependent degradation.
2Reliability
If the inductance value is increased to shift the common mode transmission zero to a lower frequency, then common mode noise suppression is improved, but the length of conducting lines increases causing larger layout size and higher line losses
Solution Approach 1:
The patent employs spiral (curved) winding geometry instead of straight conducting lines to achieve the required inductance values. The spiral configuration increases the effective length of the conducting path within a compact area, providing both the necessary inductance and the magnetic coupling between adjacent windings while controlling the overall layout size.
Solution Approach 2:
The patent transitions from planar straight-line layouts to three-dimensional spiral configurations, utilizing the vertical dimension and radial spacing to achieve higher inductance values without proportionally increasing the footprint area. The spiral windings are arranged in multiple layers with optimized spacing to maximize inductance density.
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 circuit board module achieves effective suppression of common mode noise across a wide frequency range without increasing insertion loss for differential mode signals, even at high frequencies, due to the absence of ferromagnetic materials.
Implementation Method 1
the mutual inductance coupling coefficient between the spiral winding segments of two adjacent ones of the conducting lines is greater than 0.3
Implementation Method 2
the conducting lines cooperatively form a common mode choke structure in which the conducting lines extend in such a way that each of the conducting lines has a spiral winding segment
Data Source
AI summary
A circuit board module capable of suppressing common mode noise includes a circuit board, and a first circuit and a second circuit that are disposed on the circuit board. The circuit board includes an insulating substrate, and a plurality of metal layers. The metal layers are disposed in the insulating substrate, are spaced apart from each other, and include a first metal layer and a second metal layer. The metal layers are formed to include a plurality of conducting lines. The conducting lines cooperatively form a common mode choke structure in which the conducting lines extend in a spiral pattern, so that each of the conducting lines has a spiral winding segment in the spiral pattern. In the spiral pattern, a mutual inductance coupling coefficient between the spiral winding segments of two adjacent ones of the conducting lines is greater than 0.3.