BAWR Compensation Layers for Temperature-Stable Frequency
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Solution Overview
Problem
The limited frequency resources in mobile communication terminals require a band gap between transmission and reception frequencies, which reduces available frequency resources and necessitates a reduction in this gap to prevent signal interference, while existing technologies struggle to maintain reliable operation across varying temperatures.
Innovation Solution
A bulk acoustic wave resonator (BAWR) with a compensation layer that adjusts the temperature coefficient of frequency (TCF) to zero, allowing for a narrow band gap between transmission and reception frequencies, is implemented. This BAWR includes a piezoelectric layer and electrodes with materials that modify resonance frequencies based on temperature, and compensation layers made of silicon oxide or silicon nitride doped with impurities to fine-tune the TCF.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a band gap is maintained between transmission and reception frequencies to prevent signal interference, then communication reliability is improved, but available frequency resources are reduced
Solution Approach 1:
The patent applies parameter changes by introducing compensation layers with specific temperature coefficients to counteract the temperature-induced frequency drift of the BAWR. By carefully selecting materials and thicknesses of compensation layers, the overall temperature coefficient of frequency is adjusted to minimize frequency variation, enabling stable operation across temperature ranges with reduced band gap requirements.
2Quantity of substance
If the band gap is reduced to increase available frequency resources, then frequency resource utilization is improved, but signal interference between transmission and reception increases
Solution Approach 1:
The patent reduces signal interference by changing the temperature stability parameter of the resonator through compensation layers. This allows for narrower band gaps without increasing interference, as the compensated BAWR maintains more stable resonance frequencies across temperature variations, reducing frequency drift that would cause interference.
3Reliability
If compensation layers are added to adjust the temperature coefficient of frequency, then frequency stability across temperature is improved, but device complexity increases
Solution Approach 1:
The patent uses composite material structures by combining the BAWR piezoelectric layer with compensation layers made of different materials (such as silicon oxide, silicon nitride, or other dielectric materials). These composite layered structures enable temperature compensation through the different thermal and piezoelectric properties of the constituent materials, achieving frequency stability without requiring complex active control systems.
Solution Approach 2:
The compensation layers are strategically positioned at specific locations within the BAWR structure (between electrodes or around the piezoelectric layer) to provide localized temperature compensation. This local quality approach allows temperature coefficient adjustment without requiring complete structural redesign of the entire resonator.
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 BAWR with a low TCF ensures reliable operation across ambient temperatures, providing a narrow band gap and reducing frequency variance, thus enhancing communication efficiency and expanding frequency resources without signal interference.
Implementation Method 1
a piezoelectric layer disposed between the first electrode and the second electrode
Implementation Method 2
at least one compensation layer including a material that adjusts the resonance frequency modified based on the temperature in a direction opposite to a direction of the modification
Data Source
AI summary
A bulk acoustic wave resonator (BAWR) includes a bulk acoustic resonance unit and at least one compensation layer. The bulk acoustic resonance unit includes a first electrode, a second electrode, and a piezoelectric layer disposed between the first electrode and the second electrode. The first electrode, the second electrode, and the piezoelectric layer each include a material that modifies a resonance frequency based on a temperature, and the at least one compensation layer includes a material that adjusts the resonance frequency modified based on the temperature in a direction opposite to a direction of the modification.