Multilayer LC Filter Layout for Lower Coupling Loss
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Solution Overview
Problem
Multilayered LC filters face challenges in improving attenuation characteristics without increasing filter loss, particularly due to strong coupling between resonators in portable communication devices, which affects signal attenuation in non-pass bands.
Innovation Solution
The LC filter configuration includes resonance circuits connected to input and output terminals directly with ground vias, reducing magnetic coupling and enhancing attenuation characteristics while maintaining Q values by positioning ground vias symmetrically around signal transfer paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the number of resonator stages is increased to improve attenuation characteristics in non-pass bands, then attenuation performance is improved, but filter loss increases due to stronger coupling between resonators
Solution Approach 1:
The patent introduces ground vias as intermediary elements between resonators to control and adjust the coupling strength. These ground vias act as mediators that can be strategically positioned to weaken magnetic coupling between adjacent resonators, thereby reducing filter loss while maintaining the necessary number of stages for adequate attenuation performance.
Solution Approach 2:
The patent modifies the coupling parameters between resonators by adjusting the position, size, and distribution of ground vias. By changing these geometric parameters, the magnetic coupling strength is controlled to achieve optimal balance between attenuation characteristics and filter loss, allowing multiple resonator stages to be used without proportionally increasing loss.
2Reliability
If ground vias are positioned to reduce magnetic coupling between resonators, then attenuation characteristics improve, but the structural complexity increases
Solution Approach 1:
The patent applies local quality by positioning ground vias specifically at locations where magnetic coupling is strongest between adjacent resonators. Rather than uniformly distributing ground vias throughout the structure, they are strategically placed in critical coupling regions, thereby achieving effective decoupling with minimal additional structural complexity.
Solution Approach 2:
The patent employs asymmetric positioning of ground vias relative to the resonator configuration. The ground vias are not symmetrically distributed but are placed asymmetrically to target specific coupling paths between resonators, optimizing the weakening of magnetic coupling while maintaining a relatively simple overall structure.
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 configuration effectively improves attenuation in non-pass bands while preventing an increase in filter loss, achieving up to 60 dB attenuation and maintaining comparable bandwidth and insertion loss in pass bands.
Implementation Method 1
achieves desired filter characteristics by means of magnetic coupling and/or capacitive coupling between the resonator of each stage and adjacent other resonators
Implementation Method 2
achieves desired filter characteristics by means of magnetic coupling and/or capacitive coupling between the resonator of each stage and adjacent other resonators
Data Source
AI summary
An LC filter includes an input terminal, an output terminal, a multilayer body, plate electrodes, connection electrodes connecting the plate electrodes, capacitor electrodes, and a inductor vias. Each of the capacitor electrodes opposes the plate electrode. One end of an inductor via is connected with the input terminal with a capacitor electrode interposed therebetween. Another end of the inductor via is connected to an intermediate point of a connection electrode. An inductor via is connected between the plate electrode and a capacitor electrode. An inductor via is connected between the plate electrode and a capacitor electrode. One end of an inductor via is connected with the output terminal with a capacitor electrode interposed therebetween. Another end of the inductor via is connected to an intermediate point of a connection electrode.