Multilayer Low-Pass Filter Coil Layout for High Inductance Q
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Solution Overview
Problem
Existing low-pass filters face a challenge in increasing coil inductance without reducing the Q value, as increasing the number of conductive layers leads to increased resistance and decreased Q value due to the connection of conductive layers to external electrodes on the side surface of the multilayered substrate.
Innovation Solution
A low-pass filter design featuring a laminate with a plurality of insulating layers, a first external electrode, and a first coil with via-hole conductors extending from the coil ends to the external electrode, allowing for increased inductance while maintaining low resistance and preventing Q value reduction by optimizing the connection between the coil and external electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the number of conductive layers of each coil is increased to increase inductance, then the inductance value increases, but the resistance increases and the Q value decreases
Solution Approach 1:
The patent transitions from planar conductive layers to three-dimensional via-hole conductors that extend vertically through multiple insulating layers. This dimensional change allows the coil structure to achieve increased inductance through vertical stacking while maintaining low resistance by providing direct vertical connection paths to external electrodes, thereby preventing Q value degradation.
Solution Approach 2:
The via-hole conductors serve as intermediary elements that connect the coil structures to external electrodes. These intermediaries provide low-resistance vertical connection paths, eliminating the need for extensive lateral conductive layer connections that would increase resistance and reduce the Q value while still achieving the desired inductance increase.
2Length of moving object
If the distance between the bottom of the external electrode and the region in which the conductive layer and the external electrode are connected is increased, then the inductance increases, but the resistance increases and the Q value decreases
Solution Approach 1:
The patent utilizes the vertical dimension through via-hole conductors to increase the effective inductance path length without increasing the lateral distance that would contribute to resistance. The via-hole conductors provide direct vertical connections that minimize resistive losses while allowing the coil structure to achieve the required inductance through multi-layer stacking.
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 significant increase in coil inductance while maintaining a high Q value by reducing the resistance through strategic via-hole conductor placement, ensuring efficient signal processing without interference from magnetic fields.
Implementation Method 1
The first via-hole conductor extends from the second end of the first coil toward the first side in the stacking direction. The first external electrode and the second end of the first coil are electrically coupled to each other through the first via-hole conductor.
Implementation Method 2
The first coil is incorporated in the laminate, has a spiral shape having a central axis extending in the stacking direction, and includes a first end on the first side in the stacking direction and a second end on a second side in the stacking direction.
Data Source
AI summary
A low pass filter includes a laminate including a plurality of insulating layers stacked in a z-axis direction and a mounting surface on a negative side in the z-axis direction. An external electrode is disposed on a lower surface of the laminate and is grounded. The laminate houses a substantially spiral coil having a central axis extending in the z-axis direction. Via-hole conductors extend from the end on the positive side in the z-axis direction of the coil toward the negative side in the z-axis direction. The external electrode and the end on the positive side in the z-axis direction of the coil are electrically coupled to each other through the via-hole conductors.