Multi-Pitch SAW Resonator Reflectors for Spurious Signal Suppression

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Solution Overview

Problem

Existing surface acoustic wave (SAW) resonators face challenges in effectively suppressing spurious signals and reducing discontinuities in filter insertion loss due to standing waves and external reflections, particularly when resonators with overlapping apertures have uniform electrode finger pitches.

Innovation Solution

Implementing surface acoustic wave resonators with interdigital transducer (IDT) and reflector electrodes featuring varying pitches, including a first constant pitch for IDT electrodes and increasing pitches for reflector electrodes, to minimize spurious signal generation and improve filter performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If uniform pitch is used for electrode fingers in SAW resonators, then manufacturing is simplified, but spurious signals and discontinuities in filter insertion loss increase

Engineering Contradiction:

Improveelectrode fabrication simplicityVSAvoidspurious signal magnitude

Core Design Contradiction:

Ease of manufactureVSObject-generated harmful factors

Solution Approach 1:

The patent applies local quality by varying the pitch of reflector electrode fingers across different regions. The first reflector portion has a first pitch while the second reflector portion has a second pitch different from the first, creating spatially varying local properties that suppress spurious signals at different locations within the resonator structure

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The reflector electrodes are segmented into multiple portions with different pitches. This segmentation divides the uniform reflector structure into distinct zones (first reflector portion and second reflector portion), each with optimized pitch characteristics for suppressing different spurious signal components

Inventive Principle:

Principle #1Segmentation

2Device complexity

If uniform pitch is used for electrode fingers, then device complexity is reduced, but filter insertion loss discontinuities worsen

Engineering Contradiction:

Improveelectrode pitch configurationVSAvoidfilter insertion loss continuity

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

Different pitch values are assigned to different reflector portions based on their specific functional requirements. The first reflector portion uses a first pitch optimized for its region, while the second reflector portion uses a second pitch optimized for its region, creating locally optimized performance that improves overall filter reliability

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The pitch parameter is deliberately changed across different reflector portions rather than maintaining a constant value. This parameter variation (from first pitch to second pitch) is used to control acoustic wave reflections and suppress spurious signals, thereby improving filter insertion loss characteristics

Inventive Principle:

Principle #35Parameter changes

3Object-generated harmful factors

If varying pitches are implemented for reflector electrodes, then spurious signal suppression improves, but manufacturing complexity increases

Engineering Contradiction:

Improvespurious signal magnitudeVSAvoidelectrode fabrication complexity

Core Design Contradiction:

Object-generated harmful factorsVSEase of manufacture

Solution Approach 1:

The reflector electrode structure is segmented into discrete portions with different pitches, which can be fabricated as separate elements or blocks. This segmentation allows each portion to be manufactured independently with its specific pitch, then assembled into the complete resonator structure

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Each reflector portion is manufactured with its specific local pitch requirement. The first reflector portion is fabricated with the first pitch and the second reflector portion with the second pitch, allowing localized optimization without requiring complete redesign of the entire electrode structure

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 modified pitch profile significantly reduces spurious signal magnitude and discontinuities in filter insertion loss, enhancing the overall performance of SAW filters.

Implementation Method 1

a die comprising a plurality of surface acoustic wave resonators

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

reflector electrodes with reflector electrode fingers having at least two different pitches

Methodology Applied

Scientific EffectAcoustic wave reflection: Reflection

Data Source

PatentUS20260025123A1Surface acoustic wave filter including resonator with multi-staged reflector

Publication Date: 2026.01.22 SKYWORKS SOLUTIONS INC

AI summary

Aspects and embodiments disclosed herein include a die comprising a plurality of surface acoustic wave resonators. At least one of the plurality of surface acoustic wave resonators has an aperture that at least partially overlaps an aperture of at least one other of the plurality of surface acoustic wave resonators. The at least one of the plurality of surface acoustic wave resonators includes interdigital transducer electrodes with interdigital transducer electrode fingers having a first average pitch and reflector electrodes with reflector electrode fingers having at least two different pitches. Each of the at least two different pitches are greater than the first average pitch.