Bragg Resonator Structure for Border Mode Harmonic Suppression
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Solution Overview
Problem
The presence of a border ring in resonators introduces border mode harmonics, which negatively affect the performance of radio frequency filters, particularly in electronic devices like mobile phones, by causing fluctuations in the passband and deteriorating filter performance.
Innovation Solution
A resonator design incorporating a Bragg reflection layer with a low acoustic-impedance structure and a first high acoustic-impedance structure with a discontinuous structure, such as a groove or step, is used to suppress border mode harmonics. The high acoustic-impedance structure is embedded within the low acoustic-impedance structure and has a large radial-to-circumferential size ratio, altering the acoustic wave reflection state and maintaining a high quality factor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a border ring is disposed on the resonator to improve quality factor, then the quality factor is improved, but border mode harmonics are introduced that deteriorate filter performance
Solution Approach 1:
The resonator structure is segmented into distinct functional regions: a first resonance region without border ring for main resonance, and a second resonance region with border ring for quality factor enhancement. The Bragg reflection layer is also segmented with alternating high and low acoustic impedance structures to control wave propagation differently in each region, allowing simultaneous achievement of high Q-factor and suppression of border mode harmonics.
Solution Approach 2:
Different regions of the resonator are given different structural qualities: the first resonance region has a simple structure optimized for main resonance, while the second resonance region incorporates the border ring for Q-factor enhancement. The Bragg reflection layer uses alternating high and low acoustic impedance structures with different properties in different regions to achieve localized control over acoustic wave behavior, suppressing border mode harmonics where needed while maintaining high Q-factor where required.
2Reliability
If a border ring is added to the resonator, then quality factor is improved, but the structure complexity increases
Solution Approach 1:
The resonator is divided into two functional regions: a first resonance region without border ring that maintains simple structure, and a second resonance region with border ring that enhances quality factor. This segmentation allows the simple structure to be preserved where possible while adding complexity only where needed for Q-factor improvement.
Solution Approach 2:
The border ring structure serves multiple functions: it enhances the quality factor of the resonator while also being integrated into the Bragg reflection layer design. The alternating high and low acoustic impedance structures in the Bragg reflection layer simultaneously provide acoustic isolation and support the border ring configuration, reducing overall structural complexity despite the added functionality.
3Object-generated harmful factors
If the first high acoustic-impedance structure with discontinuous structure is used, then border mode harmonics are suppressed, but manufacturing complexity increases
Solution Approach 1:
The Bragg reflection layer is segmented into alternating high acoustic impedance structures and low acoustic impedance structures, with the high impedance structures having discontinuous configurations. This segmentation enables effective suppression of border mode harmonics through the discontinuous high impedance regions while maintaining manufacturability by using standard layered deposition techniques that can create such patterns through mask-based processes.
Solution Approach 2:
The acoustic impedance parameters of the Bragg reflection layer structures are optimized to achieve effective border mode harmonic suppression. By carefully selecting the impedance values, thicknesses, and discontinuous pattern geometries of the high and low acoustic impedance structures, the design achieves harmonic suppression while maintaining compatibility with existing semiconductor manufacturing processes.
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 proposed resonator design effectively suppresses border mode harmonics, improving the passband of filters and maintaining a high quality factor while being feasible to manufacture with a low complexity process.
Implementation Method 1
a Bragg reflection layer... Along the stacking direction, the Bragg reflection layer includes a low acoustic-impedance structure and a first high acoustic-impedance structure embedded in the low acoustic-impedance structure... configured to reflect an acoustic wave
Implementation Method 2
a piezoelectric layer... A first electrode is disposed on a surface that is of the piezoelectric layer and that faces the Bragg reflection layer, and a second electrode is disposed on a surface that is of the piezoelectric layer and that is away from the Bragg reflection layer
Implementation Method 3
The discontinuous structure corresponds to the second resonance region, and the discontinuous structure herein is configured to suppress a border mode harmonic... affecting propagation of an acoustic wave
Data Source
AI summary
Disclosed are a resonator and a manufacturing method thereof, a filter, and an electronic device. The resonator includes a substrate, a Bragg reflection layer, and a piezoelectric layer that are sequentially stacked. A first electrode is disposed on a surface that is of the piezoelectric layer and that faces the Bragg reflection layer, a second electrode is disposed on a surface that is of the piezoelectric layer and that is away from the Bragg reflection layer, a border ring is disposed on a surface that is of the second electrode and that is away from the piezoelectric layer, and the resonator has a first resonance region and a second resonance region corresponding to the border ring.