Shared Acoustic Track XBAR Filters for Wideband 5G RF
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Solution Overview
Problem
Current RF filters using acoustic wave resonators are not well-suited for higher frequencies and wider bandwidths required in future communications networks, such as those defined in the 5G NR standard, which necessitates the development of more effective band-pass filters capable of handling higher frequency bands and wider communication channel bandwidths.
Innovation Solution
The use of Transversely-Excited Film Bulk Acoustic Resonators (XBARs) with shared acoustic tracks in RF filters, which allows for a more compact design and improved performance by acoustically coupling series and shunt resonators, reducing the footprint and enabling efficient handling of higher frequency bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If traditional acoustic wave resonators (SAW, BAW, FBAR) are used in RF filters, then the filters can operate at standard frequencies, but they cannot effectively handle higher frequencies and wider bandwidths required for future communication networks
Solution Approach 1:
The patent changes the fundamental operating parameters of the resonator by transitioning from surface acoustic wave (SAW) or bulk acoustic wave (BAW) modes to transverse electric (TE) mode resonators. This parameter change enables operation at higher frequencies (e.g., 28 GHz and above) while maintaining the required performance characteristics for wideband 5G communication systems
Solution Approach 2:
The patent replaces traditional mechanical acoustic wave propagation mechanisms (SAW/BAW) with an electromechanical resonator structure that uses piezoelectric materials to generate and detect acoustic waves in TE mode. This substitution enables higher frequency operation and better bandwidth performance while maintaining the acoustic filtering function
2Device complexity
If separate acoustic tracks are used for series and shunt resonators, then each resonator can be independently designed, but the overall filter footprint becomes larger
Solution Approach 1:
The patent merges the acoustic tracks of series and shunt resonators into a shared common acoustic track. Multiple resonators (both series and shunt types) are acoustically coupled through this shared track, allowing them to share the same physical space and significantly reducing the overall filter footprint while maintaining independent electrical design capabilities
Solution Approach 2:
The shared acoustic track serves multiple functions simultaneously: it acts as the acoustic path for both series resonators and shunt resonators, provides acoustic coupling between different resonator types, and enables compact integration of multiple resonators in a single filter structure. This multi-functionality reduces the number of separate components needed
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 XBARs with shared acoustic tracks provide enhanced performance and reduced manufacturing costs by allowing for smaller filter designs that can effectively handle the higher frequency bands and wider bandwidths needed for future communication systems, such as 5G NR, while maintaining high electromechanical coupling and frequency capability.
Implementation Method 1
The resonator includes a piezoelectric material and an interdigital transducer (IDT) formed on a surface of the piezoelectric material
Implementation Method 2
High performance RF filters for present communication systems commonly incorporate acoustic wave resonators including surface acoustic wave (SAW) resonators, bulk acoustic wave (BAW) resonators
Implementation Method 3
A radio frequency (RF) filter is a two-port device configured to pass some frequencies and to stop other frequencies
Data Source
AI summary
Acoustic filters devices and methods of making the same. A filter device includes two or more series resonators acoustically coupled along a shared acoustic track, and two or more shunt resonators electrically coupled to the two or more series resonators.