XBAR Matrix Filter Switching for Wideband 5G Frequency Selection
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Solution Overview
Problem
Current RF filters, including those using acoustic wave resonators, are not well-suited for the higher frequencies and wider bandwidths required by future communication networks, such as the 5G NR standard, which necessitates the development of more effective filters for frequencies above 3 GHz and wider communication channel bandwidths.
Innovation Solution
The use of Transversely-Excited Film Bulk Acoustic Resonator (XBAR) matrix filters with noncontiguous passbands and sub-filters connected in parallel, incorporating XBARs and switchable sub-filter configurations to achieve improved frequency selectivity and bandwidth capabilities, allowing for the design of filters suitable for frequencies above 3 GHz and supporting the 5G NR standard.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional acoustic wave resonators are used, then the filter structure is simple, but the frequency range is limited to below 3 GHz and bandwidth is insufficient
Solution Approach 1:
The filter is divided into multiple sub-filters, each handling a specific frequency band. Each sub-filter contains a subset of resonators that are selectively activated. This segmentation allows the overall filter to achieve wide bandwidth and high frequency capability (above 3 GHz) while keeping each individual sub-filter relatively simple in structure.
Solution Approach 2:
The patent employs switchable resonator configurations where resonators can be dynamically enabled or disabled based on the required frequency band. This dynamic reconfiguration allows the same physical filter structure to adapt to different frequency ranges and bandwidth requirements, achieving versatility without requiring multiple fixed filters.
2Adaptability or versatility
If more resonators are added to increase bandwidth, then bandwidth capability improves, but device complexity and size increase
Solution Approach 1:
Resonators are grouped into different sets, with each set assigned to handle specific frequency bands. Not all resonators are active simultaneously; instead, only the resonators needed for the current bandwidth requirement are enabled. This segmentation allows the filter to achieve high bandwidth capability when needed while maintaining lower complexity for narrower band operations.
Solution Approach 2:
The same resonator structure serves multiple functions across different frequency bands. By configuring resonators in different sets and using switching mechanisms, each resonator can contribute to multiple bandwidth scenarios, reducing the total number of resonators needed compared to having separate filters for each band.
3Measurement precision
If switchable sub-filter configurations are implemented, then frequency selectivity improves, but device complexity increases
Solution Approach 1:
The filter implements dynamic switching between different resonator sets to achieve precise frequency selection. By enabling or disabling specific resonators based on the desired frequency band, the filter achieves high frequency selectivity. The switching mechanism is integrated into the filter structure, allowing dynamic reconfiguration without adding excessive external complexity.
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 XBAR matrix filters provide enhanced frequency selectivity and bandwidth capabilities, enabling efficient filtering across the required frequency ranges with low loss and high rejection, addressing the limitations of existing technologies in handling higher frequencies and wider bandwidths.
Implementation Method 1
Transversely-Excited Film Bulk Acoustic Resonator (XBAR) matrix filters
Implementation Method 2
XBARs are acoustic resonators that rely on the piezoelectric effect to convert electrical signals to acoustic waves and back
Data Source
AI summary
There are disclosed matrix filters having an input port and sub-filters connected between the input port and respective output ports. Each of the sub-filters includes a ladder circuit with n transversely-excited film bulk acoustic resonator (XBAR) series elements and n−1 capacitor shunt elements, where n, the order of the sub-filter, is an integer greater than 2. Each sub-filter further has a first switch in parallel with a first capacitor shunt element and a second switch in parallel with a last capacitor shunt element.