BAW Resonator Plate Geometry for Lateral Spurious Wave Suppression
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current high-power filters in mobile communication devices, such as wireless base stations, are large in size, making them unsuitable for integration into RF front-end chips, and they struggle to suppress crosstalk between lateral spurious waves and longitudinal bulk acoustic wave signals in film bulk acoustic wave resonators (BAWRs).
Innovation Solution
A film bulk acoustic wave resonator design featuring a piezoelectric oscillation plate with an irregular polygonal boundary, sandwiched between two electrodes, is developed, along with a fabrication method that includes forming cavities and conductive films on substrates to minimize lateral spurious waves and enhance energy efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If cavity filters are used to achieve high power (hundreds of watts), then power capability is improved, but size becomes too large for integration into RF front-end chips
Solution Approach 1:
The patent employs thin film structures to create BAW resonators that can be integrated into RF front-end chips. The film-based construction enables high power capability while maintaining a compact form factor suitable for chip integration, directly resolving the contradiction between power capability and size.
2Power
If dielectric filters are used to achieve power over 5 watts, then power capability is improved, but size remains very large
Solution Approach 1:
The patent uses thin film BAW resonator technology to achieve compact high-power filters. The film-based construction enables power capability exceeding 5 watts while maintaining a small size suitable for modern communication devices, resolving the contradiction between power and size.
3Ease of manufacture
If regular polygonal boundaries are used in piezoelectric oscillation plates, then manufacturing is simplified, but lateral spurious waves and standing wave oscillations increase
Solution Approach 1:
The patent employs irregular polygonal boundaries for the piezoelectric oscillation plate instead of regular polygons. This asymmetric design disrupts the formation of standing wave oscillations and reduces lateral spurious waves, while the irregular shape can still be fabricated using standard photolithography and etching processes, thus resolving the contradiction between manufacturing ease and spurious wave suppression.
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 solution effectively reduces energy consumption and improves filtering performance by eliminating standing wave oscillations and minimizing lateral spurious wave energy, thereby enhancing the quality factor of the BAWR.
Implementation Method 1
an acoustic-wave resonant plate, including a first electrode, a piezoelectric oscillation plate, and a second electrode stacked on the first insulating material layer
Implementation Method 2
how to suppress the lateral resonant waves and their reflection in the piezoelectric film and also minimize the reduction of the energy consumption due to the acoustic waves propagating out from the device oscillation plate
Data Source
AI summary
A film bulk acoustic wave resonator includes a first substrate; a first insulating material layer, formed on the first substrate; a first cavity, formed in the first insulating material layer with an opening facing away from the first substrate; and an acoustic-wave resonant plate, including a first electrode, a piezoelectric oscillation plate, and a second electrode stacked on the first insulating material layer. The piezoelectric oscillation plate is disposed between the first electrode and the first electrode. The first electrode includes a first electrode cavity above the first cavity. The second electrode includes a second cavity above the first cavity. At least a portion of a boundary of the piezoelectric oscillation plate is formed by a boundary of the first electrode cavity and a boundary of the second electrode cavity. The boundary of the piezoelectric oscillation plate has an irregular polygonal shape without having two parallel edges.