BAW Powerbar and Quadbar Layout for Beat Mode Suppression
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Solution Overview
Problem
In bulk acoustic wave (BAW) resonators, the acoustic and electromagnetic asymmetries lead to differences in series and parallel resonant frequencies, causing beat modes that degrade the second harmonic suppression performance, especially in ultra-high-band (UHB) operation where shunt resonators become too small.
Innovation Solution
The implementation of powerbar and quadbar configurations with capacitive loading of individual resonators to compensate for differences in parasitic capacitance, combined with shielding structures for equipotentialing, to mitigate beat mode issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If powerbar configuration is used in UHB operation, then shunt resonators can be placed in powerbar configuration, but beat mode is generated at fp inside the passband causing unwanted spikes
Solution Approach 1:
The patent adjusts the resonant frequency parameters of individual resonators within the powerbar by modifying their physical dimensions or material properties. This parameter tuning allows the resonators to operate at slightly different frequencies, thereby eliminating the beat mode phenomenon that occurs when all resonators operate at the same frequency in UHB powerbar configurations.
2Manufacturing precision
If individual resonators have different parasitic capacitance, then manufacturing variations occur, but beat mode performance degrades
Solution Approach 1:
The patent introduces shielding structures (ground planes) positioned at specific potentials around the resonators. These shielding structures create equipotential regions that compensate for differences in parasitic capacitance between individual resonators. By establishing equal potential distributions, the system achieves uniform electrical characteristics despite manufacturing variations, thereby preventing beat mode generation.
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 effectively suppresses beat modes, maintaining the performance of BAW filters by compensating for parasitic capacitance differences and reducing unwanted spikes in linear and thermal responses.
Implementation Method 1
a piezoelectric layer disposed on the bottom electrode
Implementation Method 2
Bulk acoustic wave (BAW) resonators, such as thin-film bulk acoustic resonators (FBAR)
Implementation Method 3
capacitive loading of individual resonators to compensate for differences in parasitic capacitance
Implementation Method 4
shielding structures for equipotentialing, to mitigate beat mode issues
Data Source
AI summary
A resonator for beat mode suppression is provided. A resonator includes a substrate comprising a top surface, a bottom electrode disposed on the top surface of the substrate, a piezoelectric layer disposed on the bottom electrode, and a top electrode disposed on the piezoelectric layer. The bottom electrode includes a first elongated member configured to extend longitudinally along the top surface on a first side of the substrate.