Acoustic Wave Multiplexer Layout for Higher Passband Reflection

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Solution Overview

Problem

Acoustic wave filters in multiplexers face challenges in achieving low insertion loss and high reflection coefficient in passbands, with existing solutions often degrading reflection coefficients at higher frequencies.

Innovation Solution

The implementation of a multiplexer design that includes a series inductor and shunt acoustic resonators coupled to a common node, where the first ladder stage starts with a shunt acoustic resonator, effectively increasing the reflection coefficient in higher passbands while minimizing insertion loss.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If acoustic wave filters are arranged in a multiplexer, then signal routing capability is improved, but insertion loss increases due to loading from other filters

Engineering Contradiction:

Improvesignal routing capabilityVSAvoidinsertion loss

Core Design Contradiction:

Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The multiplexer is segmented into multiple independent filter paths (first filter with first passband, second filter with second passband, third filter with third passband) that are coupled to a common node. This segmentation allows each filter to operate independently in its own passband, reducing mutual loading effects and insertion loss while maintaining signal routing capability across multiple frequency bands.

Inventive Principle:

Principle #1Segmentation

2Adaptability or versatility

If acoustic wave filters are arranged in a multiplexer, then signal routing capability is improved, but reflection coefficient decreases in passbands of other filters

Engineering Contradiction:

Improvesignal routing capabilityVSAvoidreflection coefficient

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

Each filter is designed with local quality optimization - the first filter has its reflection coefficient optimized specifically in the second passband and third passband (passbands of other filters), while the second filter has its reflection coefficient optimized in the first passband. This local quality approach ensures high reflection coefficients in the respective passbands of other filters, improving signal routing isolation and reliability.

Inventive Principle:

Principle #3Local quality

3Ease of manufacture

If conventional filter designs are used in multiplexers, then manufacturing simplicity is maintained, but reflection coefficient degrades at higher frequencies

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidreflection coefficient at higher frequencies

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent applies parameter changes to the filter design - specifically, the first filter uses a series inductor and shunt acoustic resonator configuration with specific impedance values optimized for high reflection coefficients at higher frequencies (second and third passbands). The second filter similarly uses optimized parameters for the first passband. These parameter changes maintain manufacturing simplicity while significantly improving reflection coefficient performance at higher frequencies.

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

This design achieves relatively low insertion loss and high reflection coefficients across a range of frequencies, enhancing the performance of acoustic wave filters in multiplexers by mitigating bulk mode impacts and maintaining high reflection coefficients at higher frequencies.

Implementation Method 1

The series inductor and the shunt acoustic resonator of the first filter are together arranged to increase a reflection coefficient of the first filter in the second passband

Methodology Applied

Scientific EffectImpedance transformation:

Implementation Method 2

An acoustic wave filter can include a plurality of resonators arranged to filter a radio frequency signal

Methodology Applied

Scientific EffectAcoustic resonance: Resonance

Implementation Method 3

A surface acoustic wave resonator can include an interdigital transductor electrode on a piezoelectric substrate. The surface acoustic wave resonator can generate a surface acoustic wave on a surface of the piezoelectric layer

Methodology Applied

Scientific EffectSurface acoustic wave: Surface Acoustic Wave

Implementation Method 4

In BAW resonators, acoustic waves propagate in a bulk of a piezoelectric layer

Methodology Applied

Scientific EffectBulk acoustic wave: Acoustic Radiation Pressure

Implementation Method 5

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentUS11742829B2Multiplexer with filter having increased reflection characteristic

Publication Date: 2023.08.29 SKYWORKS SOLUTIONS INC

AI summary

Aspects of this disclosure relate to a multiplexer that includes at least a first filter having a first passband and a second filter having a second passband. The first filter includes acoustic wave resonators coupled to a common node by a series inductor. The acoustic wave resonators start with a shunt acoustic resonator from the common node. The series inductor and the shunt acoustic resonator of the first filter are together arranged to increase a reflection coefficient of the first filter in the second passband.