High-Velocity BAW Resonator Structure for Wideband RF Filtering
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Solution Overview
Problem
Conventional bulk acoustic wave resonators have limitations in frequency range, insertion loss, and filtering performance, particularly in mobile communication systems, where they cannot effectively filter radio frequency signals across a wide range of frequencies due to insufficient out-of-band rejection and poor rectangularity.
Innovation Solution
A bulk acoustic wave resonator design featuring a piezoelectric layer with an acoustic velocity of at least 18000 m/s, made from materials like hexagonal boron nitride, and incorporating a structure with a first electrode, a piezoelectric layer, and a second electrode, along with additional layers such as an inducing layer and encapsulation, to enhance frequency range and filtering efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional bulk acoustic wave resonator materials are used, then the resonator structure is simple to manufacture, but the frequency range is limited and insertion loss is high
Solution Approach 1:
The patent changes the acoustic velocity parameter of the piezoelectric layer material to at least 18000 m/s, which is significantly higher than conventional materials. This parameter change enables the resonator to operate at higher frequencies (1 GHz to 30 GHz) with lower insertion loss while maintaining manufacturing feasibility through established thin film deposition techniques
Solution Approach 2:
The patent employs composite material structure consisting of piezoelectric layer (such as AlN, ZnO, or PZT), electrode layers (such as Mo, Co, Ag, Ti, Pt, Ru, W, or Au), and base substrate materials. This composite approach optimizes both acoustic performance and electrical properties while maintaining compatibility with standard manufacturing processes
2Reliability
If conventional filter designs are used, then the device structure is simple, but out-of-band rejection is insufficient and rectangularity is poor
Solution Approach 1:
The filter is segmented into multiple resonator units (first resonator and second resonator) with different resonant frequencies (first resonant frequency and second resonant frequency). Each resonator handles specific frequency bands, enabling the filter to achieve high out-of-band rejection and good rectangularity across wide frequency ranges (1 GHz to 30 GHz) while maintaining a relatively simple overall structure
Solution Approach 2:
The patent transitions from single-frequency resonators to multi-frequency resonator systems operating in different dimensional frequency spaces. By designing resonators with different resonant frequencies and combining them in a filter structure, the system achieves superior frequency selectivity and rectangularity without significantly increasing structural complexity
3Adaptability or versatility
If higher acoustic velocity materials are used in the piezoelectric layer, then frequency range and filtering performance improve, but material selection and manufacturing precision requirements increase
Solution Approach 1:
The patent specifies a minimum acoustic velocity parameter of 18000 m/s for the piezoelectric layer material, enabling operation across an extended frequency range (1 GHz to 30 GHz). While this increases material selection criteria, it maintains manufacturing precision through well-established thin film deposition techniques and standard piezoelectric materials with known properties
Solution Approach 2:
The patent applies different material properties to different layers: the piezoelectric layer uses materials with high acoustic velocity (at least 18000 m/s) for frequency control, while electrode layers use materials with high electrical conductivity (such as Mo, Co, Ag, Ti, Pt, Ru, W, or Au). This local optimization of material quality achieves high frequency range adaptability while managing manufacturing precision through specialized material selection for each functional layer
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 achieves low insertion loss, small in-band ripple, large out-of-band rejection, and good rectangularity, enabling effective filtering across a wider frequency range, particularly from 1 GHz to 30 GHz, thereby improving signal quality in mobile communication systems.
Implementation Method 1
a radio frequency signal enters into the resonator from an electrode at one end of the resonator, then 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 2
the acoustic wave signal is transmitted to the electrode at the other end of the resonator, and is converted into the radio frequency signal at the interface of the metal electrode and the piezoelectric material through a piezoelectric effect
Implementation Method 3
the acoustic wave signal is formed as a resonant standing wave with a certain frequency in the sandwich structure including the first electrode, the piezoelectric material and the second electrode
Data Source
AI summary
The present disclosure provides a bulk acoustic wave resonator, a method for manufacturing a bulk acoustic wave resonator and an electronic device, and belongs to the field of communication technology. The bulk acoustic wave resonator of the present disclosure 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 second electrode is on a side of the first electrode away from the first base substrate, the piezoelectric layer is between the first electrode and the second electrode; and orthographic projections of any two of the first electrode, the piezoelectric layer and the second electrode on the first base substrate at least partially overlap with each other; wherein an acoustic velocity of a material of the piezoelectric layer is no less than 18000 m/s.