Multilayer Filter Phase Balance via Grounded Coil Segmentation
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Solution Overview
Problem
The existing multilayer balanced filters face challenges in setting a phase balance between balanced output terminals due to the direct connection of inductor ends to the output terminals, making it difficult to achieve a desired phase balance characteristic.
Innovation Solution
A multilayer filter design with an unbalanced-side inductor connected to a ground and a balanced-side inductor electromagnetically coupled with the unbalanced-side inductor, where the balanced-side inductor has a helical coil electrode connected to the ground at a specific point for phase reference, and a grounding capacitor is used to separate DC bias from signal frequencies, allowing for accurate phase balance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the inductor ends are directly connected to the balanced output terminals, then the structure is simple, but the phase balance between terminals cannot be accurately controlled
Solution Approach 1:
The inductor structure is segmented into multiple sections along its winding direction, with each section having different ground connection configurations. This segmentation allows independent control of phase balance at different terminal pairs while maintaining the overall inductor structure, resolving the contradiction between structural simplicity and phase balance accuracy.
Solution Approach 2:
Ground connection electrodes are introduced as intermediary elements between the inductor and ground. These electrodes provide additional connection points that enable precise phase balance control without requiring direct connection between inductor ends and output terminals, thus maintaining structural simplicity while achieving high precision.
2Manufacturing precision
If the coil electrode is connected to ground at multiple points, then the phase balance can be controlled, but the device complexity increases
Solution Approach 1:
The ground connection electrodes serve multiple functions: they provide phase reference potential, enable phase balance control, and act as return paths for current. This multi-functionality reduces the need for separate components, achieving high precision phase balance without proportionally increasing device complexity.
Solution Approach 2:
Multiple ground connection points are established along the coil electrode to maintain equipotential regions. This creates stable phase reference points that simplify the control of phase balance while avoiding the need for complex active control circuits, thus managing device complexity.
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 design achieves a high-accuracy balance characteristic by optimizing the ground connection point and electromagnetic coupling, reducing insertion loss and ensuring stable phase balance regardless of the filter's mounting configuration.
Implementation Method 1
a balanced-side inductor electromagnetically coupled with the unbalanced-side inductor
Data Source
AI summary
A multilayer filter includes a laminate including a plurality of dielectric layers stacked on each other. Inner layer electrodes and outer terminals are provided in the laminate. A second coil electrode constituting a balanced-side inductor is defined by one of the inner layer electrodes. The second coil electrode has a coiled shape, and includes a first end connected to a first coil electrode through a via electrode and a second end connected to a third coil electrode through a via electrode. The second coil electrode is connected at a predetermined position along the winding direction thereof to a ground terminal, as one of the outer terminals, through an electrode for connection to a ground. The position where the ground connection electrode is connected to the second coil electrode is determined based on a balance characteristic in the balanced terminal side.