Bulk Acoustic Wave Resonator Functional Layer for Temperature Drift
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Solution Overview
Problem
Existing bulk acoustic wave resonators face challenges in maintaining frequency stability due to temperature drift, which affects their performance in filtering radio frequency signals.
Innovation Solution
A bulk acoustic wave resonator is designed with a functional layer made of conductive materials such as antimony, bismuth, or gallium, which is integrated between the piezoelectric layer and the electrodes. This functional layer suppresses temperature drift by adjusting the temperature coefficient of the resonator within a range of −10 ppm/K to +10 ppm/K.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional bulk acoustic wave resonator structure is used, then the device is simple to manufacture, but the frequency stability deteriorates due to temperature drift
Solution Approach 1:
The patent applies composite materials by integrating a functional layer with specific temperature coefficient characteristics into the resonator structure. This functional layer, positioned between the piezoelectric layer and the substrate, compensates for temperature drift through its unique material properties, thereby improving frequency stability without significantly complicating the manufacturing process
Solution Approach 2:
The patent implements parameter changes by adjusting the temperature coefficient of the resonator through the functional layer. The functional layer's specific material composition and thickness are designed to modify the overall temperature drift characteristics of the resonator, achieving a temperature coefficient within a specified range and thus improving frequency stability
2Reliability
If existing resonator designs are used, then the manufacturing process is straightforward, but the out-of-band rejection is insufficient
Solution Approach 1:
The functional layer serves as a composite material component that enhances the resonator's filtering characteristics. By incorporating this layer with specific acoustic and thermal properties, the resonator achieves improved out-of-band rejection while maintaining a relatively simple sandwich structure configuration
Solution Approach 2:
The functional layer is positioned specifically between the piezoelectric layer and the substrate, applying local quality enhancement at the critical interface where temperature compensation and acoustic wave control are most needed. This localized improvement enhances out-of-band rejection without requiring complex modifications throughout the entire resonator structure
3Reliability
If a simple sandwich structure is used, then the device complexity is low, but the in-band ripple is large
Solution Approach 1:
The functional layer acts as a composite material that smooths out in-band ripple by providing temperature compensation and acoustic impedance matching. This layer, with its specific material composition, reduces variations in resonant frequency across the passband, thereby decreasing in-band ripple while maintaining the overall simplicity of the sandwich structure
Solution Approach 2:
The functional layer serves as an intermediary between the piezoelectric layer and the substrate, mediating the interaction between these components. This intermediary layer compensates for temperature effects and acoustic impedance mismatches, resulting in reduced in-band ripple without requiring complex modifications to the existing sandwich structure
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 integration of the functional layer significantly improves the frequency stability and performance of the bulk acoustic wave resonator, achieving low insertion loss, small in-band ripple, large out-of-band rejection, and good rectangularity, making it suitable for high-frequency applications in mobile communication.
Implementation Method 1
a material of the functional layer has a positive temperature coefficient, and is configured such that a temperature drift coefficient of the bulk acoustic wave resonator is in a range from −10 ppm/K to +10 ppm/K
Implementation Method 2
is converted into an acoustic wave signal of mechanical vibration at an interface of the piezoelectric material and the metal electrode through an inverse piezoelectric effect
Implementation Method 3
is converted into the radio frequency signal at the interface of the metal electrode and the piezoelectric material through a piezoelectric effect
Data Source
AI summary
A bulk acoustic wave resonator, a method for manufacturing a bulk acoustic wave resonator and an electronic device are provided, and belongs to the field of communication technology. The bulk acoustic wave resonator includes: a first base substrate, a first electrode, a piezoelectric layer, and a second electrode; the first electrode is on the first base substrate; the piezoelectric layer is on a side of the first electrode away from the first base substrate; the second electrode is on a side of the piezoelectric layer away from the first electrode; a functional layer is formed on a side of the piezoelectric layer close to the first base substrate and/or on a side of the piezoelectric layer away from the first base substrate; the functional layer is made of a conductive material, and the functional layer is configured to suppress a temperature drift of the bulk acoustic wave resonator.