Carbon-Based Bulk Acoustic Wave Resonator for Stable RF Frequency
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Solution Overview
Problem
Existing bulk acoustic wave resonators face challenges in achieving high acoustic wave propagation speed, low electric resistance, and stable heat characteristics, especially when ambient temperature changes, which affect their performance in wireless communication devices.
Innovation Solution
The use of carbon-based materials, such as carbon nanotubes and graphene, for the electrodes and temperature coefficient of frequency (TCF) compensation layers in bulk acoustic wave resonators, which improve acoustic wave reflection characteristics and reduce temperature-related frequency variance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If traditional metal electrodes are used in bulk acoustic wave resonators, then electrical conductivity is achieved, but acoustic wave propagation speed is limited and temperature stability is poor
Solution Approach 1:
The patent changes the material parameters of the electrodes from traditional metals to carbon-based materials (carbon nanotubes, graphene). These carbon-based materials have fundamentally different physical parameters including higher acoustic wave propagation speed and near-zero temperature coefficient of frequency, thereby resolving the contradiction between speed and temperature stability
Solution Approach 2:
The patent employs composite material structures where carbon-based materials are integrated with piezoelectric layers to form the resonator. The carbon-based electrodes combine electrical conductivity with superior acoustic properties and thermal stability, achieving both high speed and reliability simultaneously
2Speed
If carbon-based materials are used for electrodes, then acoustic wave propagation speed increases, but manufacturing complexity increases
Solution Approach 1:
The patent replaces traditional mechanical sputtering or evaporation processes for metal electrode deposition with chemical vapor deposition (CVD) methods for growing carbon-based materials. This substitution enables better control over material properties and simplifies the manufacturing process for carbon-based electrodes
Solution Approach 2:
By changing the deposition method parameters (using CVD instead of physical vapor deposition) and controlling growth conditions (temperature, pressure, gas composition), the patent achieves manufacturable processes for carbon-based electrodes while maintaining their superior acoustic properties
3Use of energy by moving object
If conventional electrodes are used, then device structure is simple, but electric resistance is high and power efficiency is low
Solution Approach 1:
The patent changes the electrical conductivity parameter of the electrodes by using carbon-based materials with inherently lower resistivity. This material parameter change directly improves power efficiency by reducing ohmic losses in the electrode structures
Solution Approach 2:
The patent uses thin-film carbon-based electrode structures that can be deposited in ultra-thin layers while maintaining low resistance. These thin-film electrodes reduce material usage and simplify the overall device structure compared to traditional thick metal electrode layers
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 enhances the resonator's acoustic wave propagation speed, reduces electric resistance, and stabilizes heat characteristics, leading to improved performance and reliability in wireless communication devices by maintaining a near-zero temperature coefficient of frequency.
Implementation Method 1
improve acoustic wave reflection characteristics
Implementation Method 2
In response to a high frequency signal being applied to the electrodes, the piezoelectric layer oscillates
Data Source
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AI summary
Provided is a bulk acoustic wave resonator (BAWR). The BAWR may include a first electrode, a piezoelectric layer disposed on the first electrode, a second electrode disposed on the piezoelectric layer. In various aspects, at least one of the first electrode, the piezoelectric layer, and the second electrode are formed of a carbon-based material.