Interdigital Resonator Layout for Spurious Peak Suppression

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Solution Overview

Problem

Real resonators typically produce spurious peaks that interfere with target modes when combined in a circuit or device, leading to unwanted signal interference.

Innovation Solution

A resonator device is designed with a first and second interdigital transducer, where at least one of the electrode width or pitch of the first transducer differs from the respective electrode width or pitch of the second transducer, allowing for reduced amplitude of spurious peaks when both are electrically connected, thereby decoupling unwanted acoustic modes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If multiple resonators are combined in a circuit or device, then the target mode signal strength is improved, but spurious peaks appear that interfere with the target mode

Engineering Contradiction:

Improvetarget mode signal strengthVSAvoidspurious peaks

Core Design Contradiction:

PowerVSObject-generated harmful factors

Solution Approach 1:

The patent applies local quality by making each interdigital transducer have different electrode characteristics (different electrode widths, pitches, or numbers of electrode pairs) while maintaining the same resonant frequency. This local differentiation causes each transducer to generate different spurious peak patterns, and when combined in parallel, these different patterns interfere destructively, reducing the overall spurious peak amplitudes while maintaining the target mode signal strength.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent employs asymmetry by intentionally designing the interdigital transducers with asymmetric electrode configurations relative to each other. Specifically, at least one transducer has different electrode parameters (width, pitch, or number of pairs) compared to the others, creating asymmetric spurious peak distributions that cancel out when combined, thereby reducing harmful interference while preserving the symmetric target mode response.

Inventive Principle:

Principle #4Asymmetry

2Object-generated harmful factors

If interdigital transducers have different electrode configurations, then spurious peaks are reduced, but manufacturing complexity increases

Engineering Contradiction:

Improvespurious peaksVSAvoidfabrication process

Core Design Contradiction:

Object-generated harmful factorsVSEase of manufacture

Solution Approach 1:

The patent applies parameter changes by modifying specific geometric parameters of the interdigital transducers (electrode width, electrode pitch, or number of electrode pairs) while keeping the resonant frequency constant. These parameter variations are designed to shift spurious peak frequencies and reduce their amplitudes when transducers are combined, achieving signal quality improvement through controlled geometric parameter differentiation.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent segments the electrode structure into multiple interdigital transducer units, each with slightly different electrode configurations. By dividing the overall resonator system into these segmented transducer elements with differentiated parameters, the patent enables independent optimization of each segment's spurious peak characteristics while maintaining ease of fabrication through standardized design modules.

Inventive Principle:

Principle #1Segmentation

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 resonator device effectively attenuates spurious peaks while maintaining the target mode frequency, improving inter-device mode decoupling without external components and enabling monolithic fabrication on a single chip.

Implementation Method 1

both the first interdigital transducer and the second interdigital transducer are configured to resonate at a common frequency

Methodology Applied

Scientific EffectResonance: Resonance

Implementation Method 2

Each of the first interdigital transducer and the second interdigital transducer may include a common bottom electrode, a piezoelectric layer over the common bottom electrode, and a top electrode over the piezoelectric layer

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentUS11811390B2Resonator devices and methods of fabricating resonator devices

Publication Date: 2023.11.07 GLOBALFOUNDRIES SINGAPORE PTE LTD

AI summary

According to various embodiments, there is provided a resonator device that includes a first interdigital transducer and a second interdigital transducer that is electrically connected to the first interdigital transducer. Both the first interdigital transducer and the second interdigital transducer are configured to resonate at a common frequency. At least one of an electrode width and an electrode pitch of the first interdigital transducer is different from the respective electrode width and/or electrode pitch of the second interdigital transducer such that spurious peaks of the resonator device are lower in amplitude as compared to spurious peaks of each of the first interdigital transducer and the second interdigital transducer.