Layered Low-Pass Filter Grounding Path Design
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Solution Overview
Problem
Existing layered low-pass filters face challenges in increasing attenuation in specific narrow frequency bands within the stop band without increasing insertion loss, particularly when the narrow frequency band is close to the cut-off frequency, as the attenuation pole closest to the pass band is difficult to adjust effectively.
Innovation Solution
A layered low-pass filter design featuring a series connection of first and second inductors, capacitors, and a conducting portion that connects the grounding conductor layer to the grounding terminal via a path longer than the shortest distance, creating a second attenuation pole at a lower frequency, allowing for increased attenuation in specific narrow frequency bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a notch filter is provided in series to increase attenuation in a specific narrow frequency band, then attenuation in that frequency band is improved, but insertion loss in the pass band increases
Solution Approach 1:
The patent changes the inductance parameter of the external electrode portion by adjusting its length. This modifies the frequency position of the attenuation pole to achieve better attenuation in specific frequency bands without requiring additional notch filters, thereby avoiding increased insertion loss in the pass band
Solution Approach 2:
The patent utilizes the spatial dimension of the external electrode length to control the electrical characteristic (inductance) and thereby control the attenuation pole frequency. This provides an additional degree of freedom for frequency control without adding complex filter structures
2Measurement precision
If the attenuation pole frequency is adjusted by changing the external electrode length, then the frequency position of the attenuation pole is improved, but it is difficult to increase attenuation in frequency bands higher than the cut-off frequency
Solution Approach 1:
The patent divides the grounding structure into multiple segments: a grounding conductor layer within the layered substrate and external electrode portions extending from the substrate. This segmentation allows independent optimization of each part's contribution to the overall attenuation characteristic, enabling effective attenuation control in higher frequency bands
Solution Approach 2:
The external electrode portions serve multiple functions: they provide grounding connection, generate inductance for attenuation pole control, and extend the effective grounding range to higher frequency bands. This multi-functionality allows the same structure to address both low-frequency and high-frequency attenuation requirements
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 effectively increases attenuation in specific narrow frequency bands within the stop band without the need for additional notch filters, maintaining low insertion loss and satisfying size and thickness reduction requirements for portable electronic devices.
Implementation Method 1
a conducting portion (6) provided within the layered substrate and connecting the grounding conductor layer (441) to the grounding terminal (25)
Implementation Method 2
a layered low-pass filter that includes: a layered substrate (20) including a plurality of dielectric layers (31-44) stacked
Data Source
AI summary
A layered low-pass filter includes: a layered substrate; an input terminal, an output terminal and a grounding terminal each disposed on a periphery of the layered substrate; first and second inductors connected in series and provided between the input terminal and the output terminal; first to fifth capacitors formed within the layered substrate; a grounding conductor layer provided within the layered substrate; and a conducting portion formed within the layered substrate. The conducting portion includes a conductor layer connected to the grounding terminal, and a conducting path formed of a plurality of through holes. The conducting portion connects the grounding conductor layer to the grounding terminal via a path longer than the shortest distance between the grounding conductor layer and the grounding terminal.