Multilayer Filter Air-Core Flux Path Design

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Solution Overview

Problem

Miniaturization of multilayer filters leads to increased eddy-current loss due to magnetic flux obstruction by capacitors and inductors, resulting in higher insertion loss.

Innovation Solution

The multilayer filter design includes a region in the stacking direction where the air-core portion of the inductors is not obstructed by capacitors or inductors, allowing magnetic flux to pass through, reducing eddy-current loss and insertion loss.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If the multilayer filter is miniaturized to reduce size, then the size of the filter is reduced, but the air-core portion of inductors is obstructed by capacitors or other inductors in the stacking direction, causing increased eddy-current loss and insertion loss

Engineering Contradiction:
Improvesize of multilayer filterVSAvoideddy-current loss and insertion loss
Core Design Contradiction:
Volume of moving objectVSLoss of energy

Solution Approach 1:

The patent applies dimensional arrangement by distributing inductors and capacitors across multiple stacked dielectric layers. Specifically, first and second inductors are placed in a first inductor layer, while first to fifth capacitors and a third inductor are placed in subsequent layers. This vertical separation in the stacking direction creates unobstructed air-core portions for the first and second inductors, allowing magnetic flux to pass through without being blocked by capacitor electrodes or other inductors, thereby reducing eddy-current loss while maintaining compact overall size.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Area of stationary object

If capacitors and inductors are arranged closely to reduce device size, then the device becomes more compact, but magnetic flux from inductor air-core portions is blocked by capacitor electrodes, generating eddy currents and heat

Engineering Contradiction:
Improvearrangement space for inductors and capacitorsVSAvoideddy current and heat generation
Core Design Contradiction:
Area of stationary objectVSObject-generated harmful factors

Solution Approach 1:

The patent segments the arrangement space for inductors and capacitors into distinct regions across multiple dielectric layers. The first inductor layer contains first and second inductors with their air-core portions, while capacitor layers contain first to fifth capacitors. By separating these components into different layers with appropriate spacing, the patent ensures that capacitor electrodes do not obstruct the magnetic flux paths of the inductors, preventing eddy current generation while maintaining compact overall device dimensions.

Inventive Principle:
Principle #1Segmentation

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 design reduces insertion loss by minimizing eddy-current loss, improving the performance of multilayer filters in compact wireless communication devices.

Implementation Method 1

most of the magnetic flux generated at the air-core portion is blocked by an electrode of the capacitor

Methodology Applied
Scientific EffectMagnetic flux: Electromagnetic Induction

Implementation Method 2

an eddy current occurs at the electrode, which generates heat (eddy-current loss)

Methodology Applied
Scientific EffectEddy current: Eddy Currents

Data Source

PatentEP3276643B1Multilayer filter
Publication Date: 2019.08.07 MURATA MFG CO LTD
  • EP3276643B1 patent drawingFigure 1~2
  • EP3276643B1 patent drawingFigure 3
  • EP3276643B1 patent drawingFigure 4

AI summary

A multilayer filter according to an embodiment of the present invention is formed by a plurality of dielectric layers. The multilayer filter includes a first terminal, a second terminal, a first inductor, a second inductor, and first to fifth capacitors. In the stacking direction of the plurality of dielectric layers, at least one of a first air-core portion formed by the first inductor and a second air-core portion formed by the second inductor includes, in the region from the first inductor layer to the second inductor layer, a region enabling magnetic flux to pass therethrough without being obstructed by the first to fifth capacitors and the third inductor.