Split-band Duplexer Filter Assembly with Switching Circuitry
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Solution Overview
Problem
Existing duplexer filters in cellular communication systems require a large guard band between frequency bands, which limits miniaturization and efficient use of bandwidth, especially with the allocation of new frequency bands like 2.5 and 2.7 GHz, necessitating a solution for high rejection with minimal or no guard band in a compact form.
Innovation Solution
A duplexer filter assembly with separate, selectably coupled filters using acoustic wave or resonator filters and MEMS switches allows for split-band operation at disparate frequency bands, enabling high rejection between receive and transmit bands without the need for a guard band, and is designed to be compact in size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a guard band is used to separate frequency bands in existing duplexer filters, then high rejection between receive and transmit bands is achieved, but the device size increases and bandwidth utilization decreases
Solution Approach 1:
The duplexer filter is divided into separate transmit and receive filter sections, each optimized for its specific frequency band. This segmentation allows independent optimization of each filter's characteristics, enabling high rejection ratios without requiring a guard band between the frequency bands, thereby reducing overall device size and improving bandwidth utilization.
Solution Approach 2:
The patent employs advanced filter design techniques that change key parameters such as filter order, topology, and component values to achieve steep roll-off characteristics. By optimizing these parameters, the filter achieves high rejection between bands without needing a guard band, thus reducing the frequency spectrum waste and device size.
2Reliability
If a guard band is used to separate frequency bands, then high rejection between receive and transmit bands is achieved, but bandwidth utilization decreases
Solution Approach 1:
By segmenting the duplexer into separate transmit and receive filter paths, each filter can be independently optimized for its designated band. This eliminates the need for a guard band between bands, allowing adjacent frequency bands to be fully utilized for communication, thereby maximizing bandwidth utilization while maintaining high rejection ratios.
Solution Approach 2:
The patent uses optimized filter parameters including higher order filtering and specialized topologies that achieve sharp frequency selectivity. This allows the filters to provide high rejection between bands without requiring frequency separation through guard bands, thus enabling full utilization of the allocated spectrum and improving bandwidth efficiency.
3Reliability
If conventional duplexer filters are used, then high rejection between frequency bands is achieved, but the device complexity and size increase
Solution Approach 1:
The duplexer filter is segmented into distinct transmit and receive filter sections with separate signal paths. This segmentation allows each section to be independently designed and optimized, simplifying the overall structure by eliminating the need for complex guard band management while maintaining high rejection performance through dedicated filter designs for each band.
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 solution achieves high rejection levels between receive and transmit bands, allowing for increased bandwidth usage and reduced size, enabling efficient operation in new frequency bands with minimal physical dimensions, such as those proposed for 2.5 and 2.7 GHz, while eliminating the need for guard bands.
Implementation Method 1
A first duplexer filter is selectably coupled to the communication circuitry. The first duplexer filter exhibits frequency pass bands at frequencies of a first frequency-band subset of the frequency-band set. A second duplexer filter is also selectably coupled to the communication circuitry. The second duplexer filter exhibits frequency pass bands at frequencies of a second frequency-band subset of the frequency-band set.
Implementation Method 2
A duplexer filter assembly with separate, selectably coupled filters using acoustic wave or resonator filters
Data Source
AI summary
A duplexer filter assembly, and an associated method, for a communications device capable of operation at a frequency-band set. Separate duplexer filters, each formed of a transmit part and a receive part, are switchingly coupled to the communication circuitry of the communication device. A selected one, or the other, of the duplexer filters is connected to the communication circuitry by switch circuitry depending upon at which parts of the communication device is to be operated.