Adjacent Filter Inductor Layout for Magnetic Coupling Cancellation

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Solution Overview

Problem

Inductive coupling between adjacent filters in electronic circuits leads to mutual interference, resonance shifting, and undesired attenuation or amplification, which degrades filter performance.

Innovation Solution

Arrange adjacent filters such that at least one inductor of a filter has an opposite polarity to its neighbor by alternating the winding direction, canceling magnetic coupling currents.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If filters are implemented physically adjacent to one another, then space is saved and integration is improved, but magnetic coupling between inductors causes interference and performance degradation

Engineering Contradiction:

Improvespace utilizationVSAvoidmagnetic coupling interference

Core Design Contradiction:

Area of stationary objectVSObject-affected harmful factors

Solution Approach 1:

The patent applies the principle of converting harmful magnetic coupling into beneficial cancellation by introducing dummy inductors that generate opposing magnetic fields. The dummy inductors are positioned adjacent to the signal inductors and carry currents that create magnetic fields equal in magnitude but opposite in direction, thereby canceling the harmful coupling effects and converting the interference problem into a solution.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The dummy inductors serve as intermediary elements that mediate between the signal inductors of adjacent filters. These dummy inductors do not directly process signal information but instead provide magnetic field cancellation, acting as a buffer that eliminates the harmful interaction between adjacent filter inductors while allowing the filters to remain physically close.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Area of stationary object

If inductors are placed close together to reduce area, then manufacturing precision requirements increase due to coupling sensitivity

Engineering Contradiction:

Improveinductor spacingVSAvoidcoupling tolerance

Core Design Contradiction:

Area of stationary objectVSManufacturing precision

Solution Approach 1:

By introducing dummy inductors specifically designed to generate canceling magnetic fields, the patent converts the sensitive coupling effect into a controllable parameter. The dummy inductors are sized and positioned to provide precise cancellation, thereby reducing the impact of manufacturing variations on overall filter performance and relaxing the effective tolerance requirements.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent changes the magnetic field parameters by adding dummy inductors with specific inductance values and positioning them at optimized distances from the signal inductors. This parameter adjustment creates a magnetic cancellation effect that compensates for variations in physical dimensions, thereby reducing sensitivity to manufacturing precision requirements.

Inventive Principle:

Principle #35Parameter changes

3Object-affected harmful factors

If shielding is added between adjacent filters to eliminate coupling, then isolation is improved but device complexity and area increase

Engineering Contradiction:

Improvefilter isolationVSAvoidshielding structure

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent extracts the magnetic field cancellation function from the traditional shielding approach and implements it through dummy inductors. Instead of using physical shielding materials that block magnetic fields, the solution extracts the essential function of field management and implements it through active inductive elements that generate canceling fields, thereby eliminating the need for complex shielding structures.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The dummy inductors serve as intermediary elements that provide isolation between adjacent filters without requiring physical shielding. These inductors mediate the magnetic interaction by generating canceling fields, achieving filter isolation through electromagnetic cancellation rather than physical barriers, thereby reducing device complexity and area.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 arrangement significantly improves filter performance by eliminating induced coupling currents, reducing noise, and eliminating the need for shielding between filters.

Implementation Method 1

magnetic coupling currents induced into one another are canceled

Methodology Applied

Scientific EffectMagnetic coupling: Electromagnetic Induction

Data Source

PatentUS12562706B2Isolation between filters using inductive coupling cancellation

Publication Date: 2026.02.24 APPLE INC

AI summary

Techniques for isolation between filters using inductive coupling cancellation are disclosed. An apparatus includes a first filter including a first plurality of inductors and a second filter including a second plurality of inductors. The first and second filters are implemented physically adjacent to one another. First and second ones of the first plurality of inductors and a first one of the second plurality of inductors are polarized in a first direction, while a second one of the second plurality of inductors is polarized in a second direction opposite that of the first direction. The second one of the second plurality of inductors is physically adjacent to one of the first and second ones of the first plurality of inductors such that magnetic coupling currents induced into one another are canceled.