SAW Filter Assembly for Wide Passband and Stopband Reflection
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Solution Overview
Problem
Existing RF filter assemblies struggle to achieve a wider passband while maintaining improved reflection coefficients at the stopband, which is crucial for efficient signal processing in RF communication systems.
Innovation Solution
The proposed filter assembly comprises a first filter with a plurality of resonators connected in series and parallel arms, where the resonators are formed on substrates with different cut angles to broaden the passband and improve reflection characteristics at the stopband. A second filter is also included, configured to allow signals to pass at a second passband using resonators formed on a specific substrate to enhance reflection characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a filter assembly uses traditional resonator configurations, then the structure is simple and manufacturing is easier, but the passband width is limited and reflection coefficients at stopband are not optimized
Solution Approach 1:
The patent applies local quality by using different resonator types at different locations within the filter assembly. Specifically, first resonators with different electrical lengths are used in series arms while second resonators are used in parallel arms near the output terminal. This localized differentiation optimizes reflection coefficients at the stopband without requiring complete redesign of the entire filter structure, thus balancing manufacturing complexity with performance improvement.
Solution Approach 2:
The filter assembly is segmented into multiple functional sections with different resonator configurations. The series arms contain first resonators with specific electrical lengths, while parallel arms contain second resonators with different electrical lengths. This segmentation allows each section to be optimized independently for its specific function (passband transmission or stopband rejection), resolving the contradiction between overall structure simplicity and localized performance optimization.
2Manufacturing precision
If resonators are configured for narrowband filtering, then reflection characteristics at stopband are improved, but the passband width is reduced
Solution Approach 1:
The patent employs parameter changes by varying the electrical lengths of different resonators to simultaneously achieve wide passband and good stopband rejection. First resonators in series arms have electrical lengths optimized for passband transmission, while second resonators in parallel arms have different electrical lengths optimized for stopband reflection. This parameter differentiation allows the filter to achieve both wide passband width and improved reflection coefficients without compromising either characteristic.
Solution Approach 2:
The filter assembly uses a composite configuration of different resonator types (first resonators and second resonators with different electrical lengths) to achieve combined performance benefits. This composite structure integrates the advantages of narrowband resonators (good reflection characteristics) with wideband resonators (wide passband), allowing the overall assembly to achieve both wide passband width and improved stopband rejection that neither resonator type could achieve alone.
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
This configuration allows for a wider passband and improved reflection coefficients at the stopband, enhancing the overall performance of RF filter assemblies in communication systems.
Implementation Method 1
Each of the first filter and the second filter is a ladder-type surface acoustic wave filter
Implementation Method 2
a first filter configured to allow signals received via an antenna node to pass at a first passband, the first filter including a plurality of resonators
Implementation Method 3
each of the first substrate and the second substrate is a piezoelectric substrate formed of lithium niobate (LiNbO3)
Data Source
AI summary
A filter assembly operating at wider passband with an enhanced reflection coefficient is provided herein. In certain embodiments, the filter assembly comprises a first filter configured to allow signals received via an antenna node to pass at a first passband, the first filter including a plurality of resonators connected in series and parallel arms, the plurality of resonators of the first filter including a first type of resonator configured to broaden the first passband, at least a series resonator nearest to the antenna node or a shunt resonator nearest to the antenna node among the plurality of resonators of the first filter being a second type of resonator configured to improve reflection characteristics at a stopband of the first filter, and a second filter configured to allow the signals received via the antenna node to pass at a second passband using the second type of resonators.