Switched RF Multiplexer Filter Branches

Solution Overview

Problem

Conventional filtering technologies for antenna multiplexers in mobile communication devices face challenges in achieving high bandwidth and steep roll-offs at ultra-high frequencies, particularly above 3 GHz, due to limitations in both high-Q acoustic wave resonators and low-Q LC filters.

Innovation Solution

A multiplexer design with selectable high-Q and low-Q filter branches, utilizing high-Q acoustic resonators for steep roll-off and low-Q components for high bandwidth, respectively, and switchable configurations to optimize filtering performance across various frequency bands.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of moving object

If high-Q acoustic wave resonators are used, then steep roll-off is achieved, but bandwidth is limited

Engineering Contradiction:

Improveroll-off steepnessVSAvoidbandwidth

Core Design Contradiction:

Length of moving objectVSAdaptability or versatility

Solution Approach 1:

The filter is divided into multiple stages: a first filter stage using high-Q acoustic wave resonators for steep roll-off, and a second filter stage using low-Q LC circuits for extended bandwidth. This segmentation allows each stage to specialize in one function, resolving the contradiction between roll-off steepness and bandwidth.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent merges two different filtering technologies (high-Q acoustic resonators and low-Q LC circuits) into a single hybrid filter structure. The high-Q stage provides steep roll-off while the low-Q stage extends the bandwidth, combining the advantages of both technologies to resolve the contradiction.

Inventive Principle:

Principle #5Merging (Combining)

2Adaptability or versatility

If low-Q LC filters are used, then high bandwidth is achieved, but roll-off steepness is insufficient

Engineering Contradiction:

ImprovebandwidthVSAvoidroll-off steepness

Core Design Contradiction:

Adaptability or versatilityVSLength of moving object

Solution Approach 1:

The filter is divided into multiple stages: a first filter stage using high-Q acoustic wave resonators for steep roll-off, and a second filter stage using low-Q LC circuits for extended bandwidth. This segmentation allows each stage to specialize in one function, resolving the contradiction between roll-off steepness and bandwidth.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent merges two different filtering technologies (high-Q acoustic resonators and low-Q LC circuits) into a single hybrid filter structure. The high-Q stage provides steep roll-off while the low-Q stage extends the bandwidth, combining the advantages of both technologies to resolve the contradiction.

Inventive Principle:

Principle #5Merging (Combining)

3Adaptability or versatility

If frequency separation is reduced to maximize bandwidth, then available bandwidth is increased, but filtering effectiveness decreases

Engineering Contradiction:

Improveavailable bandwidthVSAvoidfiltering effectiveness

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent employs switchable filter configurations that can dynamically adapt to different frequency bands. The multiplexer can switch between different filter stages and configurations depending on the operating frequency, allowing effective filtering even when frequency separation is reduced.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The filter system can change its characteristics by switching between high-Q and low-Q stages, and between different filter configurations. This parameter change capability allows the filter to maintain effectiveness across varying frequency separations while maximizing available bandwidth.

Inventive Principle:

Principle #35Parameter changes

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 enables concurrent use of multiple ultra-high frequency bands with minimal insertion loss and steep roll-offs, effectively addressing the limitations of existing technologies by providing both high bandwidth and steep roll-off characteristics.

Implementation Method 1

technologies that provide steep roll-off, are based on resonances with a high quality factor (i.e., 'high-Q'), such as acoustic wave resonances, e.g., in Bulk Acoustic Wave (BAW) or Surface Acoustic Wave (SAW) resonator devices using piezoelectric materials

Methodology Applied

Scientific EffectAcoustic wave resonance: Surface Acoustic Wave

Implementation Method 2

acoustic wave resonances, e.g., in Bulk Acoustic Wave (BAW) or Surface Acoustic Wave (SAW) resonator devices using piezoelectric materials

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentUS10587292B2Multiplexer with switched filter branch including high-Q components

Publication Date: 2020.03.10 AVAGO TECHNOLOGIES INTERNATIONAL SALES PTE LTD

AI summary

A multiplexer includes a common port, multiple filter branches and at least one switch included in a switched filter branch of the multiple filter branches. The filter branches are connected to the common port, and each filter branch corresponds to at least one predetermined frequency band and filters a radio frequency (RF) signal according to the corresponding at least one predetermined frequency band. In a first switch state of the at least one switch, the switched filter branch includes a high-Q filter having multiple high-Q components for improving roll-off of the filtered RF signal, and in a second switch state of the at least one switch, the switched filter branch includes a low-Q filter having multiple low-Q components that support a very high bandwidth for filtering the RF signal.