Shielded Multilayer Diplexer Layout for Filter Isolation
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Solution Overview
Problem
Existing diplexers lack effective isolation between low-pass and high-pass filters, leading to degradation of frequency characteristics due to inter-line capacitance and electromagnetic coupling, and cannot adjust inductance components and stray capacitance separately for each filter.
Innovation Solution
A diplexer design with independent first and second filter ground electrodes and a shield ground electrode, where the filters are connected through separate ground terminals and a common inductor, and the shield ground electrode provides shielding between the filters, allowing for independent adjustment of inductance and capacitance components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If filters are placed adjacent to each other in a multilayer substrate to save space, then device compactness is improved, but frequency characteristics deteriorate due to inter-line capacitance and electromagnetic coupling
Solution Approach 1:
A shield ground electrode is introduced as an intermediary element between the low-pass filter and high-pass filter. This shield ground electrode acts as a mediator that blocks electromagnetic coupling and inter-line capacitance between the two filters, thereby preventing frequency characteristic degradation while maintaining the compact multilayer structure.
Solution Approach 2:
The ground electrode system is segmented into multiple independent ground electrodes (first ground electrode for low-pass filter, second ground electrode for high-pass filter, and shield ground electrode between them). This segmentation allows each filter to have its own dedicated ground reference while the shield ground electrode provides isolation, resolving the contradiction between compactness and frequency characteristics.
2Device complexity
If a common ground electrode is used for both filters to simplify structure, then device complexity is reduced, but frequency characteristics deteriorate due to inability to independently adjust inductance and capacitance components
Solution Approach 1:
The ground electrode system is divided into multiple independent ground electrodes, each serving specific filters. The first ground electrode is dedicated to the low-pass filter, the second ground electrode is dedicated to the high-pass filter, and the shield ground electrode provides isolation. This segmentation enables independent adjustment of inductance and capacitance components for each filter, improving frequency characteristics while maintaining reasonable structural complexity.
3Reliability
If shield ground electrode is added between filters to improve isolation, then frequency characteristics are improved, but device complexity increases
Solution Approach 1:
The shield ground electrode is merged with the existing ground electrode system in the multilayer substrate. By integrating the shield function into the ground electrode structure rather than adding a separate component, the patent achieves improved filter isolation while minimizing increases in device complexity. The shield ground electrode is formed using the same manufacturing processes as other ground electrodes in the multilayer substrate.
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 design ensures excellent frequency characteristics by reducing coupling between filters, allowing for optimized frequency performance of both low-pass and high-pass filters without interference from each other.
Implementation Method 1
a shield ground electrode that provides shielding between the first filter and the second filter
Data Source
AI summary
A diplexer includes a multilayer substrate, first, second, and third terminals, and a ground terminal provided on the multilayer substrate. The first filter is between the first terminal and the second terminal, the second filter is between the first terminal and the third terminal. An interlayer spacing of the multilayer substrate includes a first filter ground electrode, a second filter ground electrode, and a shield ground electrode shielding between the first filter and the second filter. The ground terminal includes a first filter ground terminal connected to the first filter ground electrode, a second filter ground terminal connected to the second filter ground electrode, and a shield ground terminal connected to the shield ground electrode.