SAW Resonator Electrode Dielectric Layout for Lower Insertion Loss
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Solution Overview
Problem
There is a need for surface acoustic wave resonators with improved loss performance, particularly in multi-layer piezoelectric substrates used in radio frequency electronic systems, as existing technologies face challenges in achieving low insertion loss and high thermal dissipation while minimizing high frequency spurious responses.
Innovation Solution
The implementation of a surface acoustic wave device comprising a piezoelectric layer, an interdigital transducer electrode, and a dielectric layer, such as tantalum pentoxide, over a silicon dioxide layer, with a quartz layer and silicon support substrate, which reduces thermal impedance and high frequency spurious responses, and includes a dielectric layer disposed over specific regions of the interdigital transducer electrode to enhance loss performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a multi-layer piezoelectric substrate is used to achieve high quality factor, then the resonator performance is improved, but the loss performance deteriorates
Solution Approach 1:
The patent applies local quality by placing a dielectric layer specifically over the interdigital transducer electrode regions (bus bar and fingers) while leaving other regions of the piezoelectric substrate exposed. This localized modification reduces loss in critical areas without affecting the overall high quality factor achieved by the multi-layer piezoelectric structure. The dielectric layer is positioned only where it provides benefit for reducing loss, rather than uniformly covering the entire substrate.
2Productivity
If the interdigital transducer electrode structure is used for signal transmission, then the filtering function is achieved, but thermal impedance increases
Solution Approach 1:
The dielectric layer is applied locally over the interdigital transducer electrode regions where thermal generation occurs, providing targeted thermal management. The layer reduces thermal impedance in the high-power regions without interfering with the signal transmission function of the electrode structure. This localized approach allows the electrode to maintain its filtering capability while reducing heat buildup in critical areas.
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 results in improved loss performance, high power durability, and reduced high frequency spurious responses, enabling low insertion loss filters suitable for wide bandwidth applications and compatibility with higher frequency bands.
Implementation Method 1
A surface acoustic wave resonator can include an interdigital transductor electrode on a piezoelectric substrate. The surface acoustic wave resonator can generate a surface acoustic wave on a surface of the piezoelectric layer on which the interdigital transductor electrode is disposed.
Implementation Method 2
A dielectric layer is disposed over the interdigital transducer electrode outside the interdigital region and configured to reduce a loss of the surface acoustic wave device.
Implementation Method 3
An acoustic wave filter can include a plurality of resonators arranged to filter a radio frequency signal. Example acoustic wave filters include surface acoustic wave (SAW) filters and bulk acoustic wave (BAW) filters.
Data Source
AI summary
Aspects of this disclosure relate to a surface acoustic wave device. The surface acoustic wave device includes a piezoelectric layer and an interdigital transducer. The interdigital transducer electrode includes a pair of electrodes, each electrode having a bus bar and fingers extending from the bus bar. The interdigital transducer electrode has an interdigital region defined by a portion of the fingers of the electrodes that interdigitate with each other. A dielectric layer is disposed over the interdigital transducer electrode outside the interdigital region and configured to reduce a loss of the surface acoustic wave device.