Mixed SAW-BAW Acoustic Wave Filter for Low Harmonic Distortion

Solution Overview

Problem

Acoustic wave filters, particularly in 5G New Radio applications, face challenges in achieving low second harmonic distortion and insertion loss, with existing BAW resonators experiencing spikes in frequency response due to lateral and recessed frame modes, while TCSAW resonators have higher insertion loss and degraded quality factor.

Innovation Solution

A multiplexer design incorporating a receive filter with a shunt SAW resonator and a plurality of BAW resonators, where the shunt SAW resonator has a resonant frequency within the transmit passband, reducing second harmonic distortion and achieving low insertion loss, and a transmit filter with a second plurality of BAW resonators, improving system-level linearity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If BAW resonators are used in acoustic wave filters, then insertion loss is reduced, but second harmonic distortion increases due to lateral and recessed frame mode spikes in frequency response

Engineering Contradiction:

Improveinsertion lossVSAvoidsecond harmonic distortion

Core Design Contradiction:

Loss of energyVSObject-generated harmful factors

Solution Approach 1:

The filter is segmented to include two distinct types of resonators: BAW resonators for reducing insertion loss and TCSAW resonators for suppressing second harmonic distortion. Each resonator type is strategically placed in different filter sections based on its performance characteristics

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different resonator types are assigned to different locations within the filter structure. TCSAW resonators are specifically placed in sections where second harmonic suppression is most needed, while BAW resonators are used in sections where low insertion loss is prioritized

Inventive Principle:

Principle #3Local quality

2Object-generated harmful factors

If TCSAW resonators are used in acoustic wave filters, then second harmonic distortion is reduced, but insertion loss increases and quality factor degrades

Engineering Contradiction:

Improvesecond harmonic distortionVSAvoidinsertion loss

Core Design Contradiction:

Object-generated harmful factorsVSLoss of energy

Solution Approach 1:

The filter is segmented to include two distinct types of resonators: BAW resonators for reducing insertion loss and TCSAW resonators for suppressing second harmonic distortion. Each resonator type is strategically placed in different filter sections based on its performance characteristics

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different resonator types are assigned to different locations within the filter structure. TCSAW resonators are specifically placed in sections where second harmonic suppression is most needed, while BAW resonators are used in sections where low insertion loss is prioritized

Inventive Principle:

Principle #3Local quality

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 design effectively reduces second harmonic distortion and maintains low insertion loss, enhancing the linearity and performance of the multiplexer, particularly in 5G New Radio applications by leveraging the better second harmonic performance of SAW resonators and the insertion loss characteristics of BAW resonators.

Implementation Method 1

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 2

The surface acoustic wave resonator can generate a surface acoustic wave on a surface of the piezoelectric layer on which the interdigital transductor electrode is disposed

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 3

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

Methodology Applied

Scientific EffectBulk acoustic wave: Acoustic Emission

Data Source

PatentUS12176883B2Acoustic wave filter including different types of resonators

Publication Date: 2024.12.24 SKYWORKS SOLUTIONS INC

AI summary

Aspects of this disclosure relate to acoustic wave filter. The acoustic wave filter can include different types of acoustic wave resonators. The acoustic wave filter can include shunt acoustic wave resonator that has lower second harmonic distortion than other acoustic wave resonators of the acoustic wave filter. In certain embodiments, the shunt acoustic wave resonator can be a surface acoustic wave resonator. Related multiplexers, radio frequency modules, wireless communication devices, and methods are also disclosed.