Multi-Spiral Layer Common Mode Filter for High Impedance

The patent transitions from a planar winding structure to a three-dimensional multilayer structure. Multiple coil patterns are stacked across different layers (first, second, third, and fourth coil patterns) with insulating layers between them, enabling the filter to achieve higher impedance without increasing the lateral footprint. This vertical stacking in the Z-dimension resolves the contradiction between impedance and area.

The patent implements a nested configuration where multiple coil patterns are embedded within each other across different layers. The first and third coil patterns are connected in series, as are the second and fourth coil patterns, creating a compact nested arrangement that maximizes the effective winding count within a confined space, thereby increasing impedance without expanding the filter's external dimensions.

The patent applies local quality by varying the geometric parameters (such as trace width, spacing, and pattern dimensions) of specific coil patterns in different layers to achieve desired cutoff frequencies. Each coil pattern can be locally optimized with different dimensions while maintaining the overall multilayer structure, allowing frequency adjustment without requiring a complete redesign of the entire coil structure.

The patent utilizes parameter changes by modifying physical dimensions of the coil patterns (such as the width, length, and spacing of conductive traces) to adjust the inductance and resonant characteristics. By changing these geometric parameters in the coil patterns, the cutoff frequency can be tuned without fundamentally altering the multilayer spiral structure, thus achieving adaptability while controlling complexity.