Acoustic-Wave Ladder Filter Topology for Low Loss and High Rejection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing radio frequency (RF) communication systems face challenges in designing bandpass filters with low in-band loss and high out-of-band rejection, particularly in supporting carrier aggregation schemes for advanced cellular technologies like 5G NR.
Innovation Solution
The development of a radio frequency acoustic filter configuration that includes series and shunt acoustic resonators, along with tunable inductors, to achieve low in-band loss and high out-of-band rejection. This configuration allows for mutual coupling between inductors and includes additional filter cells with specific inductor connections to enhance filtering performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional bandpass filter designs are used, then device complexity is reduced, but in-band loss increases and out-of-band rejection decreases
Solution Approach 1:
The filter is divided into multiple filter cells (first filter cell, second filter cell, third filter cell) with distinct functions. Each cell contains specific resonator and inductor configurations that contribute to overall performance. This segmentation allows optimization of in-band loss in certain cells while other cells focus on out-of-band rejection, resolving the contradiction between low loss and complex configuration.
Solution Approach 2:
The filter incorporates tunable inductors that can dynamically adjust their inductance values. This dynamic capability allows the filter to optimize its performance characteristics (in-band loss and out-of-band rejection) based on operating conditions, resolving the contradiction by enabling adaptive configuration rather than fixed complex structures.
2Object-generated harmful factors
If conventional bandpass filter designs are used, then device complexity is reduced, but out-of-band rejection decreases
Solution Approach 1:
Different filter cells have specialized local configurations optimized for specific functions. The first filter cell with its series resonator and coupled inductors is optimized for out-of-band rejection, while other cells handle different aspects of signal filtering. This local quality differentiation allows high out-of-band rejection without requiring every part of the filter to be maximally complex.
Solution Approach 2:
The filter employs a composite structure combining surface acoustic wave resonators, bulk acoustic wave resonators, and electromagnetic resonators in specific configurations. This composite approach leverages the strengths of different resonator types to achieve superior out-of-band rejection that would be difficult to obtain with a single resonator technology, resolving the contradiction between performance and complexity.
3Object-generated harmful factors
If filter configurations with multiple resonators and coupled inductors are used, then out-of-band rejection increases, but device complexity increases
Solution Approach 1:
Multiple filter cells are merged into a single integrated filter structure with shared components and common signal paths. The coupled inductors between cells create interconnected functionality that achieves high out-of-band rejection through coordinated operation of all cells rather than requiring each cell to independently provide maximum rejection, thus reducing overall component count while maintaining performance.
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 proposed filter configuration effectively allows transmission within a passband while providing high out-of-band rejection, which is crucial for supporting carrier aggregation and other advanced RF communication technologies.
Implementation Method 1
The series acoustic resonator and the shunt acoustic resonator can be surface acoustic wave resonators or bulk acoustic wave resonators
Implementation Method 2
The first inductor and the second inductor can be mutually coupled
Data Source
AI summary
Aspects of this disclosure relate to bandpass filters with enhanced out of band rejection. The bandpass filters include a stage that is modified using a network of three inductors two of which are mutually coupled inductors. Related methods, radio frequency systems, radio frequency modules, and wireless communication devices are also disclosed.