Tiled XBAR Filter Architecture for High-Power 5G RF Bands
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Solution Overview
Problem
Current RF filters using acoustic wave resonators are not well-suited for higher frequencies and bandwidths required in future communications networks, such as those defined in the 5G NR standard, particularly for bands n77, n79, and millimeter wave frequencies, which demand improved performance in terms of power handling and frequency range.
Innovation Solution
The development of tiled XBAR filters, which utilize transversely-excited film bulk acoustic resonators (XBARs) with interleaved IDT fingers on a piezoelectric diaphragm, allowing for higher electromechanical coupling and frequency capability, and are configured in various architectures such as ladder filters with series and shunt resonators, and tiled configurations to enhance power handling and frequency range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional acoustic wave resonators (SAW, BAW, FBAR) are used, then the filter can operate at standard frequencies, but the filter cannot handle higher frequencies and bandwidths required for 5G NR bands n77, n79, and millimeter wave communications
Solution Approach 1:
The filter is divided into multiple identical or non-identical sub-filters arranged in a tiled configuration. Each sub-filter handles a portion of the total power and frequency range, allowing the overall system to achieve both high frequency operation and high power handling capability that individual conventional resonators cannot achieve alone.
2Power
If the filter is designed for wider bandwidth and higher frequencies, then the power handling capability improves, but the insertion loss and temperature increase worsen
Solution Approach 1:
By segmenting the filter into multiple sub-filters, the power handling capacity is distributed across parallel paths. This segmentation reduces the power burden on each individual sub-filter, thereby reducing insertion loss and temperature increase while maintaining overall high power handling capability.
Solution Approach 2:
Multiple sub-filters are combined in a tiled configuration where their individual contributions to power handling and frequency range are merged. The combined system achieves superior performance in power handling and bandwidth while the distributed architecture mitigates insertion loss and thermal issues that would plague a single large filter.
3Adaptability or versatility
If tiled XBAR filter configurations are used, then power handling and frequency range improve, but the device complexity increases
Solution Approach 1:
The filter architecture is segmented into modular sub-filters that can be independently designed and fabricated. This modularity, while increasing the number of components, allows for standardized designs that can simplify the overall development and manufacturing process despite the increased device complexity.
Solution Approach 2:
The tiled XBAR filter configuration provides multi-functionality by simultaneously achieving high frequency operation, wide bandwidth, and high power handling capability. The same basic sub-filter design can be replicated and tiled to achieve different performance levels, making the architecture universally applicable across multiple 5G NR bands and frequency ranges.
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
Tiled XBAR filters demonstrate improved insertion loss, power transfer, and maximum available gain across wider frequency ranges, enabling better performance in high-frequency applications like 5G NR bands n77 and n79, and millimeter wave communications, with increased power handling and reduced temperature increase.
Implementation Method 1
a piezoelectric material such as lithium niobate, lithium tantalate, lanthanum gallium silicate, gallium nitride, or aluminum nitride
Implementation Method 2
The IDT includes a first set of parallel fingers, extending from a first busbar and a second set of parallel fingers extending from a second busbar. The first and second sets of parallel fingers are interleaved. A microwave signal applied to the IDT excites a shear primary acoustic wave in the piezoelectric diaphragm.
Data Source
AI summary
Tiled filters are disclosed. A filter includes an n×m array of sub-filters, where n is a number of sub-filters in parallel and m is a number of sub-filters in series. n and m are non-zero positive integers and at least one of n and m is greater than one. All of the nm sub-filters are bandpass filters with substantially the same passbands.