Parallel Acoustic Duplexer for High-Power Isolation and Low PIM
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Solution Overview
Problem
Current duplexer designs, particularly for high-power applications, face challenges with size, weight, cost, and power-handling capabilities, as well as passive intermodulation (PIM) and isolation requirements, where ceramic duplexers are often used due to their limitations in acoustic type duplexer designs.
Innovation Solution
The development of a duplexer utilizing multiple acoustic wave or low temperature co-fired ceramic (LTCC) band pass filters in an electrically parallel configuration, combined with 90° hybrid couplers and impedance matching circuits, to enhance power handling, reduce PIM, and improve isolation between transmit and receive ports.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If acoustic type duplexers are used, then size is reduced, but power handling capability and isolation are insufficient for high-power applications
Solution Approach 1:
The duplexer is segmented into multiple acoustic wave filters (at least three filters) operating in parallel, each handling a portion of the transmit power. This segmentation allows the system to maintain the compact size of acoustic filters while distributing the power handling load across multiple components, thereby achieving both small size and high power handling capability.
2Power
If ceramic filters are used, then power handling capability is improved, but size increases significantly
Solution Approach 1:
The patent replaces ceramic mechanical filters with acoustic wave filters that use piezoelectric effects and acoustic wave propagation. This substitution maintains power handling capability through proper circuit configuration (parallel arrangement with impedance matching) while achieving significantly smaller size, as acoustic filters are inherently more compact than their ceramic counterparts.
3Power
If multiple band pass filters are used in parallel, then power handling capability is improved, but device complexity increases
Solution Approach 1:
The patent manages complexity by carefully controlling impedance parameters - specifically designing the parallel filter configuration with matched impedances and using impedance transformation networks where needed. This parameter optimization allows multiple filters to be combined in parallel without creating significant complexity, as the impedance matching simplifies the overall circuit design and analysis.
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 results in smaller, lighter, and less expensive duplexers with improved power handling capabilities and reduced PIM, achieving higher isolation and efficiency compared to traditional designs, while maintaining a compact form factor.
Implementation Method 1
The band pass filters may be acoustic wave filters
Data Source
AI summary
Duplexers for high power applications are disclosed. In some embodiments, a duplexer includes 2N band pass filters, where N is an integer greater than 1. The 2N band pass filters each have an input and an output and are in an electrically parallel configuration. The duplexer includes a first adaptation circuit configured to couple a transmit signal received from a transmitter to each one of the 2N band pass filters. The duplexer includes a second adaptation circuit configured to couple outputs of the 2N band pass filters to an antenna, the second adaptation circuit providing an isolated path between the antenna and a receiver.