Near-Synchronous SAW Resonator Layout for Fewer Passband Spikes

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Solution Overview

Problem

Conventional dual mode surface acoustic wave (DMS) resonators suffer from passband resonance spikes due to significant asynchronous design elements, such as cavities and high pitch variations between transducers, which affect performance and manufacturability, especially in frequency bands approaching the limits of finger pitch manufacturability.

Innovation Solution

The design of DMS resonators with near synchronous operation by minimizing or eliminating the transition area between adjacent transducers, maintaining a nearly constant finger period, and controlling pitch variations to less than 3%, thereby reducing spurious parasitic modes and enhancing manufacturing feasibility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If significant asynchronous design elements (cavities and high pitch variations) are used in conventional DMS resonators, then device size is reduced, but passband resonance spikes occur affecting performance

Engineering Contradiction:

Improvedevice sizeVSAvoidpassband performance

Core Design Contradiction:

Volume of moving objectVSReliability

Solution Approach 1:

The patent applies parameter changes by controlling pitch variations to less than 3% across all IDTs and minimizing transition areas between adjacent transducers. This parameter control eliminates the harmful asynchronous design elements while maintaining the compact device structure, thereby resolving the contradiction between small size and passband performance.

Inventive Principle:

Principle #35Parameter changes

2Device complexity

If high pitch variations between transducers are used, then device complexity is reduced, but manufacturing precision becomes difficult to achieve

Engineering Contradiction:

Improvetransducer design complexityVSAvoidfinger pitch manufacturability

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The patent applies local quality by making the pitch variation consistent and controlled across all transducers rather than allowing random variations. By standardizing the pitch to vary by less than 3% uniformly across the device, the patent simplifies manufacturing while maintaining precision, resolving the contradiction between device complexity and manufacturing precision.

Inventive Principle:

Principle #3Local quality

3Object-generated harmful factors

If transition areas between adjacent transducers are minimized, then spurious parasitic modes are reduced, but device area increases

Engineering Contradiction:

Improvespurious parasitic modesVSAvoidresonator area

Core Design Contradiction:

Object-generated harmful factorsVSArea of stationary object

Solution Approach 1:

The patent applies parameter changes by optimizing the transition area dimensions and pitch variations to less than 3%, which reduces spurious parasitic modes through controlled parameter variation rather than simply minimizing area. This resolves the contradiction by using parameter control to reduce harmful effects without proportionally increasing device area.

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 configuration reduces passband spikes, improves manufacturing ease, and maintains high performance with reduced insertion loss and increased impedance, allowing for smaller and more efficient filter devices.

Implementation Method 1

Using a piezoelectric material as a vibrating medium, acoustic resonators operate by transforming an electrical signal wave that is propagating along an electrical conductor into an acoustic wave that is propagating via the piezoelectric material.

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

Near synchronous dual mode surface acoustic wave resonators

Methodology Applied

Scientific EffectSurface acoustic wave: Surface Acoustic Wave

Data Source

PatentUS12438514B2Near synchronous dual mode surface acoustic wave resonators

Publication Date: 2025.10.07 RF360 SINGAPORE PTE LTD

AI summary

An apparatus is disclosed for a surface acoustic wave (SAW) device a dual mode (DMS) resonator configuration with near synchronous operation. One aspect comprises a piezoelectric material, a first reflector disposed over the piezoelectric material, a second reflector disposed over the piezoelectric material, and a plurality of interdigitated transducers (IDTs) disposed over the piezoelectric material and positioned between the first reflector and the second reflector, wherein a magnitude of a pitch of electrode fingers in the first reflector and the second reflector is higher than a pitch of electrode fingers in the plurality of interdigitated transducers, wherein a variation of the pitch of the electrode fingers in the plurality of interdigitated transducers is less than 3% across the plurality of interdigitated transducers.