Common Mode Filter with Segmented Resonant Circuits for High-Frequency Noise
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional common-mode choke coils with large inductance and coupling coefficient are ineffective at high frequencies due to low self-resonant frequency and high signal transmission loss, making them unsuitable for high-frequency differential transmission lines like USB or HDMI.
Innovation Solution
A common mode filter with small inductance and coupling coefficient, utilizing a configuration of inductance and capacitance elements arranged in series and parallel resonant circuits, along with an ESD-protection circuit integrated into the semiconductor substrate, to effectively attenuate common mode noise across a wide frequency band with minimal differential mode signal loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If large inductance and large coupling coefficient are used in common-mode choke coil, then common mode noise suppression is improved, but self-resonant frequency decreases and transmission loss increases
Solution Approach 1:
The common-mode filter is divided into multiple independent resonant circuits (first through sixth resonant circuits) with different resonant frequencies. Each resonant circuit targets a specific frequency range, allowing effective noise suppression across a broad spectrum without requiring large inductance values that would limit the self-resonant frequency.
Solution Approach 2:
The invention changes the approach from using large inductance values to using multiple resonant circuits with carefully selected inductance and capacitance values. By adjusting the resonant frequencies of individual circuits, the filter achieves broadband noise suppression while maintaining high self-resonant frequency and low transmission loss in the operating band.
2Object-affected harmful factors
If large inductance and large coupling coefficient are used in common-mode choke coil, then common mode noise suppression is improved, but self-resonant frequency decreases
Solution Approach 1:
The filter is segmented into multiple resonant circuits, each handling a specific frequency range. This allows the overall system to achieve broadband suppression without requiring any single component to have large inductance, thereby maintaining high self-resonant frequency.
Solution Approach 2:
Instead of relying on a single dimension (inductance value) for noise suppression, the invention introduces multiple dimensions by creating several resonant circuits with different frequency characteristics. This multi-dimensional approach enables effective suppression across wide bandwidth while maintaining high self-resonant frequency.
3Object-affected harmful factors
If multiple resonant circuits with different resonant frequencies are provided, then common mode noise suppression across wide frequency band is improved, but device complexity increases
Solution Approach 1:
Multiple resonant circuits are merged into a single integrated filter structure with shared components and common signal paths. The first through sixth resonant circuits are combined such that they work together as one unified device, reducing overall complexity compared to separate filters for each frequency range.
Solution Approach 2:
The filter structure is designed with universal characteristics where the same basic resonant circuit topology is reused multiple times with different parameter values. This modular universal design simplifies the overall complexity by applying a proven template rather than designing unique circuits for each frequency range.
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 solution provides excellent high-frequency performance with small transmission loss and reduced component count on circuit boards, effectively suppressing common mode noise while maintaining low differential mode signal loss.
Implementation Method 1
a first resonant circuit (series resonant circuit) is defined by the first inductance element, the third inductance element, the second capacitance element, and the fifth inductance element; a second resonant circuit (series resonant circuit) is defined by the second inductance element, the third capacitance element, the fourth capacitance element, the fourth inductance element and the fifth inductance element; a third resonant circuit (parallel resonant circuit) is defined by the first inductance element, the first capacitance element and the second capacitance element
Implementation Method 2
a common-mode choke coil includes two coils, the two coils being configured such that magnetic fields generated around the coils by differential mode signals (normal mode signals) cancel each other out and the magnetic fields strengthen each other for common mode signals (common mode noise)
Data Source
AI summary
On a first-signal-line side, a first resonant circuit is defined by a first inductance element, a first capacitance element, a second capacitance element, a third inductance element and a fifth inductance element, a third resonant circuit is defined by the first inductance element, the first capacitance element and the second capacitance element, and a fifth resonant circuit is defined by the first inductance element, the third inductance element, the first capacitance element, the second capacitance element and the fifth capacitance element. Similarly, on a second-signal-line side, a second resonant circuit, a fourth resonant circuit and a sixth resonant circuit are provided.