High-Frequency Filter Circuit for Multi-Band Antenna Isolation

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Solution Overview

Problem

In small-size communication devices with multiple bands, achieving good isolation characteristics between transmitting/receiving circuits is challenging, leading to intermodulation distortion and degradation of receiving sensitivity, especially when multiple bands share a single antenna.

Innovation Solution

An electronic component with a first circuit and a second circuit connected in parallel, featuring filters that transmit and reflect signals with phase inversion, effectively canceling out leakage signals and improving isolation characteristics between the circuits.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple high frequency devices are mounted to support different communication methods, then communication versatility is improved, but isolation characteristics between circuits deteriorate

Engineering Contradiction:

Improvecommunication versatilityVSAvoidisolation characteristics

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

A third circuit is introduced as an intermediary between the first and second circuits. This third circuit includes a transmission filter that transmits a third transmission signal and a reception filter that transmits a third reception signal, acting as a mediator to improve isolation between the multiple communication circuits while maintaining their respective functions

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If isolation characteristics are insufficient and multiple transmitting/receiving circuits transmit simultaneously, then communication functionality is maintained, but intermodulation distortion occurs degrading receiving sensitivity

Engineering Contradiction:

Improvecommunication functionalityVSAvoidreceiving sensitivity

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The third circuit serves as a protective intermediary that prevents harmful interactions between the first and second circuits. By inserting this intermediate stage with dedicated transmission and reception filters, the system maintains communication functionality while preventing intermodulation distortion that would otherwise degrade receiving sensitivity

Inventive Principle:

Principle #24Intermediary (Mediator)

3Object-affected harmful factors

If a plurality of filters are connected in series to improve signal separation, then isolation characteristics are improved, but device complexity increases

Engineering Contradiction:

Improveisolation characteristicsVSAvoidcircuit complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The filtering function is segmented across three separate circuits rather than using a single complex filter. Each circuit handles specific frequency ranges with dedicated transmission and reception filters, distributing the complexity while achieving better overall isolation characteristics

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 solution effectively suppresses intermodulation distortion and maintains good transmission characteristics, ensuring sufficient receiving sensitivity even when multiple bands are used simultaneously.

Implementation Method 1

a first filter that transmits the first signal set and reflects the second signal set

Methodology Applied

Scientific EffectFrequency-selective transmission and reflection: Filter (electronic)

Implementation Method 2

a second filter that transmits the second signal set and reflects the first signal set

Methodology Applied

Scientific EffectFrequency-selective transmission and reflection: Filter (electronic)

Implementation Method 3

the second circuit reflects the first transmission signal and the second transmission signal, transmits a part of the first transmission signal and a part of the second transmission signal, and inverts a phase of the part of the first transmission signal and a phase of the part of the second transmission signal

Methodology Applied

Scientific EffectPhase inversion:

Data Source

PatentUS9041485B2High frequency electronic component

Publication Date: 2015.05.26 TAIYO YUDEN KK

AI summary

An electronic component includes: a first circuit connected to a first common terminal for inputting/outputting a first signal set, a second common terminal for inputting/outputting a second signal set having a frequency higher than the first signal set, and a third common terminal for being connected to an antenna; and a second circuit connected in parallel to the first circuit between the first and second common terminals, wherein the first circuit includes a first filter transmitting the first signal set and reflecting the second signal set, and a second filter transmitting the second signal set and reflecting the first signal set, the third common terminal is located between the first and second filters, and the second circuit reflects a first transmission signal and a second transmission signal, transmits parts of the first and second transmission signals, and inverts phases of the parts of the first and second transmission signals.