Phase-Cancelling SAW Filter Layout for Acoustic Interference Suppression

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Solution Overview

Problem

Existing multi-layer piezoelectric substrate surface acoustic wave devices face interference issues due to acoustic wave reflections and coupling between phase cancelling circuits and resonators, which degrade the performance of the filters.

Innovation Solution

The integration of a phase cancelling circuit with a tapered sidewall structure and strategic positioning to offset the acoustic track from resonators, combined with interference suppression structures, reduces unwanted reflections and coupling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a phase cancelling circuit is integrated with the filter circuit in an MPS-SAW device, then signal leakage is reduced and isolation is improved, but acoustic wave reflections and coupling between the phase cancelling circuit and resonators cause interference that degrades performance

Engineering Contradiction:

Improvefilter isolationVSAvoidacoustic wave interference

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent extracts and removes the harmful acoustic wave reflections by introducing acoustic wave absorption structures that selectively absorb reflected acoustic waves while allowing the main signal to pass through. This separates the harmful reflected waves from the useful signal path, eliminating the interference that degrades phase cancelling circuit performance.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces acoustic wave absorption structures as intermediary elements between the phase cancelling circuit and the resonators. These intermediary structures mediate the acoustic wave interactions by absorbing harmful reflections and preventing direct coupling between the phase cancelling circuit and resonators, thereby reducing interference while maintaining the isolation benefits.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Volume of moving object

If the phase cancelling circuit is positioned closer to the resonators to improve integration, then device compactness is improved, but acoustic wave coupling between the circuits increases causing interference

Engineering Contradiction:

Improvedevice footprintVSAvoidacoustic wave coupling

Core Design Contradiction:

Volume of moving objectVSObject-affected harmful factors

Solution Approach 1:

The patent places acoustic wave absorption structures as intermediary elements between the phase cancelling circuit and resonators. These intermediaries enable close positioning for compactness while preventing harmful acoustic wave coupling by absorbing the acoustic energy that would otherwise transfer between the closely-spaced circuits.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent applies acoustic wave absorption structures locally at specific positions where acoustic wave coupling occurs between the phase cancelling circuit and resonators. This localized treatment allows compact integration while selectively eliminating coupling interference only where needed, rather than requiring uniform spacing throughout the device.

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

Enhances filter isolation and performance by minimizing interference, achieving high isolation and reduced signal leakage in multi-layer piezoelectric substrate surface acoustic wave devices.

Implementation Method 1

surface acoustic wave (SAW) device

Methodology Applied

Scientific EffectSurface acoustic wave: Surface Acoustic Wave

Implementation Method 2

piezoelectric layer having a first side facing the support substrate

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 3

phase cancelling circuit integrated with the filter circuit

Methodology Applied

Scientific EffectPhase cancellation: Interference

Data Source

PatentUS20250317124A1Phase cancelling circuit in multi-layer piezoelectric substrate surface acoustic wave device with interference suppression structure

Publication Date: 2025.10.09 SKYWORKS SOLUTIONS INC

AI summary

A multi-layer piezoelectric substrate surface acoustic wave device is disclosed. The acoustic wave device can include a multi-layer piezoelectric substrate including a support substrate and a piezoelectric layer, a filter circuit including a plurality of resonators in electrical communication with the piezoelectric layer, a phase cancelling circuit integrated with the filter circuit, and a pair of acoustic obstruction structures including a first acoustic obstruction structure and a second acoustic obstruction structure positioned such that the phase cancelling circuit is located between the pair of acoustic obstruction structures along an acoustic track of the phase cancelling circuit.