Ground-Trace Filter Module Layout for LTE Band Isolation
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Solution Overview
Problem
Existing filter modules for multiple carrier aggregation face challenges in reducing size while maintaining sufficient cross isolation between filter bands, as increasing the number of resonators for sharper rejection increases size and reduces the number of filters that can be incorporated.
Innovation Solution
Incorporating a metallic ground trace that bisects the substrate into sections, separating filters, allowing for improved cross isolation and reduced coupling between filters, enabling smaller module size with the same or fewer resonators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the number of resonators is increased to provide sharper rejection for out of band signals, then the band pass definition is improved, but the filter size increases and the number of filters that can be incorporated on a filter module is reduced
Solution Approach 1:
The filter module is segmented into multiple sections by ground traces, with each section containing specific filters. This segmentation allows for better isolation between filters, enabling the use of fewer resonators per filter while maintaining overall system performance. The ground traces create electrical isolation that compensates for the reduced number of resonators.
Solution Approach 2:
Ground traces are introduced as intermediary elements between adjacent filters on the substrate. These ground traces act as mediators that provide electrical isolation and reduce coupling between filters, allowing filters with fewer resonators to be placed closer together on the substrate without compromising band pass definition.
2Reliability
If the spacing between filters is increased to reduce interference between filter bands, then cross isolation is improved, but the filter module size increases and fewer filters can be incorporated
Solution Approach 1:
The substrate is divided into multiple sections by ground traces, creating distinct zones for different filters. This segmentation provides electrical isolation between filters, improving cross isolation without requiring large physical spacing. Each section can be independently optimized for its specific filter requirements.
Solution Approach 2:
Ground traces are strategically placed in specific locations between filters that require isolation, rather than uniformly across the entire substrate. This local application of grounding provides targeted cross isolation where needed, while maintaining compact overall module size. The ground traces are positioned to address specific interference paths between adjacent filters.
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 metallic ground trace enhances cross isolation, allowing more filters to be included in a smaller module, reducing interference and improving signal separation without increasing module size.
Implementation Method 1
a first metallic ground trace substantially bisecting the surface of the substrate into first and second substrate sections, such that the first filter is disposed on the first substrate section and the second filter is disposed on the second substrate section
Data Source
AI summary
A filter module for multiple carrier aggregation includes a substrate, a first filter and a second filter disposed on a first side of the substrate, and a metallic ground trace substantially bisecting the surface of the substrate into first and second substrate sections, such that the first filter is disposed on the first substrate section and the second filter is disposed on the second substrate section and a method of improving cross isolation in a multiple carrier aggregation filter module including a first filter disposed on a substrate for passing a first LTE band and a second filter disposed on the substrate for passing a second LTE band having a neighboring frequency to the first LTE band, the method including bisecting the substrate with a metallic trace such that the first filter is on a different section of the substrate to the second filter.