Multilayer LC Filter Layout to Reduce Resonator Coupling
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Solution Overview
Problem
Miniaturization of multilayered LC filters leads to increased coupling between resonators, degrading filter characteristics, as positioning resonators towards the center to reduce coupling between connection electrodes and resonators results in stronger resonator coupling, affecting filter performance.
Innovation Solution
The LC filter design incorporates a multilayer body with plate-shaped electrodes and vias connecting them, reducing coupling between connection electrodes and resonance circuits, and between resonance circuits themselves, by using vias instead of side surface electrodes for connections, thereby maintaining filter quality during size reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If resonators are positioned towards the center of the multilayer body to reduce coupling between connection electrodes and resonators, then coupling between connection electrodes and resonators is reduced, but coupling between resonators increases leading to degradation of filter characteristics
Solution Approach 1:
The patent transitions from planar positioning of resonators on the inner side to three-dimensional positioning using multiple dielectric layers. By distributing resonators across different layers (first dielectric layer, second dielectric layer) and using via electrodes to connect them, the design achieves both reduced coupling with connection electrodes and maintained filter characteristics through vertical separation and strategic horizontal positioning.
2Volume of moving object
If the size of the LC filter is reduced for miniaturization, then the filter becomes more compact suitable for portable devices, but coupling between resonators increases degrading filter performance
Solution Approach 1:
The patent implements nesting by placing resonators in different dielectric layers within the same compact footprint. The first resonator is formed in the first dielectric layer while the second resonator is formed in the second dielectric layer, allowing vertical stacking that reduces the horizontal area occupied by each resonator while maintaining adequate spacing to control coupling effects.
Solution Approach 2:
The invention moves from two-dimensional planar arrangement to three-dimensional layered structure. By utilizing the vertical dimension with multiple dielectric layers and via electrodes, the filter achieves miniaturization in the horizontal plane while maintaining performance through controlled vertical and lateral spacing between resonating elements.
3Reliability
If plate-shaped connection electrodes are used on side surfaces to connect first and second electrodes, then electrical connection is achieved, but strong coupling with resonators occurs increasing filter loss
Solution Approach 1:
The patent extracts the connection function from the side surface connection electrodes and relocates it to via electrodes positioned at corners of the multilayer body. This separation removes the harmful coupling effect of side surface electrodes while preserving the essential electrical connection function through the via electrodes that connect the first electrode to the second electrode through the ground potential.
Solution Approach 2:
The via electrodes serve as intermediaries that provide the necessary electrical connection between the first electrode and second electrode while minimizing harmful coupling with resonators. By positioning via electrodes at corner locations rather than on side surfaces adjacent to resonators, the design mediates between the need for electrical connection and the need to reduce parasitic coupling.
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 reduces filter loss and improves attenuation characteristics in non-pass bands while maintaining or improving performance in pass bands, ensuring the filter characteristics are not degraded during miniaturization.
Implementation Method 1
The first inductor via and the first capacitor electrode form a first resonance circuit that receives a signal from the input terminal
Implementation Method 2
The second inductor via and the second capacitor electrode define a second resonance circuit that transfers a signal to the output terminal
Implementation Method 3
The first ground via and the second ground via connect the first electrode and the second electrode
Data Source
AI summary
An LC filter includes a multilayer body including dielectric layers layered therein, plate electrodes, capacitor electrodes, inductor vias, and ground vias. The plate electrodes are provided on different layers of the multilayer body. The capacitor electrodes each define a capacitor between itself and the electrode. The inductor via is connected with the electrode and the capacitor electrode, while the inductor via is connected with the electrode and the capacitor electrode. The ground vias connect the plate electrodes to each other. The inductor via and the capacitor electrode define a resonance circuit that receives a signal from an input terminal. The inductor via and the capacitor electrode define a resonance circuit that transfers a signal to the output terminal.