Multiplexer Filter Layout for Stable Inductance and Suppression
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Solution Overview
Problem
LC filters used in high-frequency applications, such as 5G mobile communication systems, face challenges in achieving sufficient suppression and stability due to varying inductance in matching circuits and increased filter size with multiple stages.
Innovation Solution
A filter design incorporating an acoustic wave resonator with a specific configuration of inductors and capacitors, where the ground terminal overlaps more area than the signal terminals, and inductors are strategically placed to reduce the impact of mounting distance on filter characteristics, enhancing suppression and miniaturization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the number of stages in the filter is increased to increase the suppression, then the suppression performance is improved, but the filter size becomes larger
Solution Approach 1:
The patent changes the structural parameters of the inductor by increasing the overlap area between the line and ground terminal, which increases the inductance value. This allows achieving the required suppression performance with fewer filter stages, thereby reducing the overall filter size while maintaining reliability
Solution Approach 2:
The patent utilizes the vertical dimension by stacking dielectric layers to create a three-dimensional inductor structure. The line is positioned on one dielectric layer while the ground terminal is on another layer, creating overlapping regions that generate inductance. This vertical stacking approach increases inductance without increasing the horizontal footprint, thus reducing filter size while maintaining suppression performance
2Ease of manufacture
If an inductor is used as a matching circuit in the filter, then the filter can be constructed, but the inductance varies according to the distance between the inductor and the mounting board, causing filter characteristics to vary
Solution Approach 1:
The patent performs preliminary action by pre-establishing a stable inductance value through the overlapping structure of the line and ground terminal on different dielectric layers. This inductance is determined by the fixed geometric parameters of the overlapping regions rather than by the variable distance to the mounting board, thereby ensuring filter characteristics remain stable regardless of mounting variations
Solution Approach 2:
The patent changes the inductance generation mechanism from relying on distance to mounting board to relying on the overlap area between line and ground terminal. By increasing the overlap area, the inductance value is increased and made independent of mounting distance variations, thus improving filter characteristics stability while maintaining ease of construction
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 proposed filter design improves attenuation characteristics and reduces the dependence on mounting distance, achieving better suppression and miniaturization, suitable for high-frequency applications like 5G systems.
Implementation Method 1
a filter including an acoustic wave resonator having an excellent steepness
Implementation Method 2
Filters including both an inductor and a capacitor (i.e., LC filters) have been widely used in the communications field as high-frequency filters
Data Source
AI summary
A filter includes first and second signal terminals, a filter circuit connected between the first and second signal terminals, a substrate having first and second surfaces, the first and second signal terminals being located on the first surface, a part of the filter circuit being located at a side of the second surface, a line located closer to the first surface than the filter circuit in the substrate, a first end of the line being connected to one of the first and second signal terminals, and a ground terminal that is located on the first surface and to which a second end of the line is connected, an area of a region where the line overlaps with the ground terminal being greater than an area of a region where the line overlaps with the one of the first and second signal terminals when the substrate is viewed in plan view.