Magnetically Cross-Coupled Bandpass Filter for IPD Selectivity

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Solution Overview

Problem

Current cross-coupled bandpass filters face difficulties in generating a transmission zero in a high frequency rejection band during integrated passive device (IPD) fabrication, particularly with electric cross-coupling methods, which are prone to short circuits and inefficient in producing high selectivity.

Innovation Solution

A magnetically cross-coupled bandpass filter design featuring resonators with inductors and capacitors arranged to generate positive mutual inductance, allowing for effective transmission zero creation in a high frequency rejection band, utilizing magnetic semiconductor or metal materials and symmetrical configurations to enhance selectivity and compatibility with IPD processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If electric cross-coupling is used to generate a transmission zero in a high frequency rejection band, then the selectivity is improved, but the risk of short circuits increases during IPD fabrication

Engineering Contradiction:

ImproveselectivityVSAvoidshort circuit risk

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent replaces electric cross-coupling with magnetic cross-coupling. Instead of using capacitive coupling between adjacent resonators which causes short circuits during IPD fabrication, the invention uses inductive coupling through magnetic fields. This substitution maintains the ability to generate transmission zeros for high selectivity while eliminating the harmful short circuit effect during the fabrication process

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Ease of manufacture

If magnetic cross-coupling is used during IPD fabrication, then the process compatibility is improved, but the transmission zero generation in high frequency rejection band becomes difficult

Engineering Contradiction:

ImproveIPD process compatibilityVSAvoidtransmission zero generation capability

Core Design Contradiction:

Ease of manufactureVSMeasurement precision

Solution Approach 1:

The patent introduces asymmetry in the coupling configuration between resonators. By creating asymmetric magnetic coupling paths with different coupling coefficients, the invention enables magnetic cross-coupling to generate transmission zeros in the high frequency rejection band, overcoming the limitation of conventional symmetric magnetic coupling structures

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The patent modifies the coupling parameters by adjusting the geometric parameters of the resonators and coupling elements. By changing the distance, orientation, and dimensions of the inductive coupling elements, the invention optimizes the magnetic coupling strength to achieve transmission zero generation in the desired high frequency rejection band while maintaining IPD fabrication compatibility

Inventive Principle:

Principle #35Parameter changes

3Device complexity

If conventional bandpass filter design is used, then the structure is simple, but the selectivity requirement for portable communication devices cannot be met

Engineering Contradiction:

Improvefilter structureVSAvoidpass band selectivity

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent divides the bandpass filter into multiple resonator sections with specific cross-coupling configurations. By segmenting the filter structure into resonators with controlled magnetic coupling, the invention achieves high pass band selectivity required for portable communication devices while maintaining a manageable structural complexity

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

The magnetically cross-coupled bandpass filter successfully generates a transmission zero in a high frequency rejection band, improving selectivity and process compatibility, as demonstrated by a significant transmission zero of −61.529 dB at 3.292 GHz, surpassing conventional methods.

Implementation Method 1

a magnetically cross-coupled bandpass filter design featuring resonators with inductors and capacitors arranged to generate positive mutual inductance

Methodology Applied

Scientific EffectMagnetic cross-coupling: Electromagnetic Induction

Implementation Method 2

generate positive mutual inductance, allowing for effective transmission zero creation in a high frequency rejection band

Methodology Applied

Scientific EffectMutual inductance: Electromagnetic Induction

Implementation Method 3

a second resonator comprised of a second inductor, an interconnecting inductor and a second capacitor... a first resonator comprised of a first inductor and a first capacitor... a third resonator comprised of a third inductor and a third capacitor

Methodology Applied

Scientific EffectResonance: Resonance

Data Source

PatentUS9054670B2Cross-coupled bandpass filter

Publication Date: 2015.06.09 SILICONWARE PRECISION IND CO LTD

AI summary

A cross-coupled bandpass filter includes first, second and third resonators such that a positive mutual inductance is generated between the first and third resonators and mutual inductance generated between the first and second resonators and mutual inductance generated between the second and third resonators have the same polarity, thereby generating a transmission zero in a high frequency rejection band.