Duplexer Multilayer Substrate Electromagnetic Shielding
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Solution Overview
Problem
Existing duplexer designs for mobile communication devices face challenges in reducing electromagnetic coupling between transmission and reception terminals, especially in downsized devices, leading to saturation of isolation levels.
Innovation Solution
A duplexer with a multilayer substrate and a specific arrangement of conductors and ground terminals is used to electromagnetically shield the transmission terminal, including a first conductor surrounding the area projected by the transmission terminal and ground terminals placed between the terminal and the substrate's edges, effectively blocking electromagnetic waves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the physical distance between transmission and reception terminals is increased to reduce electromagnetic coupling, then isolation characteristic is improved, but device area increases
Solution Approach 1:
The patent transitions from two-dimensional planar separation to three-dimensional spatial arrangement by stacking filter patterns across multiple layers. The transmission filter pattern is placed on a first main surface while the reception filter pattern is placed on a second main surface of a multilayer substrate, utilizing the vertical dimension to achieve electromagnetic isolation without increasing the horizontal footprint of the device.
Solution Approach 2:
The patent introduces a ground pattern as an intermediary element positioned between the transmission filter pattern and reception filter pattern. This ground pattern acts as an electromagnetic shield that blocks coupling between the two filter patterns, enabling isolation without requiring increased physical distance or area.
2Object-affected harmful factors
If shield electrodes are arranged between transmission and reception filter patterns to improve isolation, then electromagnetic coupling is reduced, but device complexity increases
Solution Approach 1:
The patent combines multiple functions into the ground pattern: it serves as both an electromagnetic shield to reduce coupling and as a reference plane for both transmission and reception filter patterns. This merged structure eliminates the need for separate shield electrodes, reducing device complexity while maintaining isolation performance.
Solution Approach 2:
The ground pattern performs multiple functions simultaneously: it acts as a shield between transmission and reception filters, provides a reference potential plane for both filter patterns, and serves as an electrical connection layer. This multi-functionality reduces the overall number of components needed compared to traditional shield electrode designs.
3Area of stationary object
If filter patterns are placed close together to reduce device area, then area is reduced, but electromagnetic coupling increases
Solution Approach 1:
The patent resolves the area-coupling tradeoff by moving the reception filter pattern to a different layer (second main surface) rather than placing it adjacent to the transmission filter pattern on the same layer. This vertical separation maintains compact horizontal area while effectively reducing electromagnetic coupling through the multilayer substrate.
Solution Approach 2:
The ground pattern serves as an intermediary barrier between the closely spaced transmission and reception filter patterns on different layers, blocking electromagnetic coupling while allowing the filters to be positioned near each other in the horizontal plane, thus maintaining small device area.
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 improves the isolation characteristic by approximately 10 dB in the transmission band and outside of passbands, reducing electromagnetic coupling and enhancing the duplexer's performance in compact device designs.
Implementation Method 1
a first conductor provided on a first surface of a first layer out of the multiple layers so as to surround at least one of a first area defined by projecting the transmission terminal onto the first layer and a second area defined by projecting the first reception terminal thereon; and a ground terminal provided on a second surface of the first layer opposite to the first surface and located between the transmission terminal and a fourth side opposite to the first side and/or between the first reception terminal and the fourth side
Data Source
AI summary
In one aspect of the invention, a duplexer including a multilayer substrate with multiple stacked layers and a back surface with a rectangular shape is disclosed. An antenna terminal, a transmission terminal, a reception terminal, a ground terminal, and a conductor are provided in various positions on the multilayer substrate for improved performance.