Shared Acoustic Track XBAR Filters for Wideband High-Frequency RF

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Solution Overview

Problem

Existing RF filters using acoustic wave resonators are not well-suited for higher frequencies and wider bandwidths required in future communication networks, such as the 5G NR standard's bands n77 and n79, and WiFi bands at 5 GHz and 6 GHz.

Innovation Solution

The use of Transversely-Excited Film Bulk Acoustic Resonators (XBARs) with shared acoustic tracks in band-pass filters, which allows for a more compact design and improved performance at higher frequencies by acoustically coupling resonators on shared diaphragms.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional acoustic wave resonators are used in RF filters, then the filters can operate at standard frequencies, but they are not well-suited for higher frequencies and wider bandwidths required in future communication networks

Engineering Contradiction:

Improvefrequency range and bandwidth capabilityVSAvoidperformance suitability for high frequency applications

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent changes the fundamental operating parameters of the resonator by transitioning from surface acoustic wave (SAW) or bulk acoustic wave (BAW) mechanisms to transverse electromagnetic (TEM) mode resonators operating at microwave frequencies. This parameter change enables the filter to handle higher frequencies (e.g., 5 GHz, 6 GHz WiFi bands, 5G NR bands) and wider bandwidths while maintaining reliability and performance

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If multiple resonators are used to achieve wider bandwidth and higher frequency performance, then the filter performance improves, but the filter footprint increases

Engineering Contradiction:

Improvebandwidth and frequency capabilityVSAvoidfilter footprint

Core Design Contradiction:

Adaptability or versatilityVSArea of stationary object

Solution Approach 1:

The patent merges multiple resonators onto a single shared diaphragm structure, allowing them to share common acoustic tracks and mechanical support. This merging approach enables multiple resonators to achieve wider bandwidth and higher frequency performance while significantly reducing the overall filter footprint compared to conventional separate resonator designs

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The shared diaphragm structure serves multiple functions simultaneously: it acts as the mechanical support for multiple resonators, provides common acoustic coupling paths, and functions as the resonating element for all resonators on the diaphragm. This multi-functionality reduces the total component count and footprint while maintaining performance

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 solution enables RF filters to handle higher transmit powers and wider bandwidths, achieving similar performance to conventional filters while significantly reducing the filter's footprint, leading to cost savings and improved manufacturing efficiency.

Implementation Method 1

Each resonator includes an interdigital transducer (IDT), with at least the fingers of the IDT disposed on the diaphragm

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

High performance RF filters for present communication systems commonly incorporate acoustic wave resonators including surface acoustic wave (SAW) resonators, bulk acoustic wave (BAW) resonators

Methodology Applied

Scientific EffectAcoustic wave propagation: Acoustics

Data Source

PatentUS12289099B2Acoustic filters with shared acoustic tracks for series and shunt resonators

Publication Date: 2025.04.29 MURATA MFG CO LTD

AI summary

Acoustic filters devices and methods of making the same. A filter device includes a first plurality of acoustic resonators including at least one first series resonator and at least one first shunt resonator. The at least one first series resonator and the at least one first shunt resonator are acoustically coupled along a first shared acoustic track.