Multilayer Multiplexer Coil Layout for Stable Filter Isolation
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Solution Overview
Problem
Existing multiplexers for mobile phones face variations in magnetic coupling due to manufacturing inaccuracies and substrate properties, leading to unstable isolation characteristics between radio-frequency filters.
Innovation Solution
A multiplexer design with a multilayer substrate featuring coil patterns on different dielectric layers, where the inductance value of one coil pattern is higher than the other, reducing variations in magnetic coupling and ensuring stable isolation characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If coil patterns are arranged close to generate magnetic coupling between inductors, then attenuation characteristics and isolation characteristics are improved, but variations in magnetic coupling degree occur due to manufacturing inaccuracies and substrate property variations
Solution Approach 1:
The patent transitions from planar arrangement of coil patterns to a three-dimensional stacked arrangement on different dielectric layers. This vertical separation in the Z-dimension reduces the impact of lateral dimensional variations while maintaining magnetic coupling through controlled proximity, thereby improving isolation characteristics stability despite manufacturing tolerances
Solution Approach 2:
The patent optimizes the inductance value ratio between coupled inductors (setting it to 0.5-2.0) and controls the number of coil patterns to achieve stable magnetic coupling. By adjusting these parameters, the system maintains consistent isolation characteristics even when subject to manufacturing variations in coil dimensions and positions
2Reliability
If coil patterns are arranged close to each other, then magnetic coupling is generated improving attenuation characteristics, but the degree of magnetic coupling varies due to substrate property variations
Solution Approach 1:
The patent introduces dielectric layers as intermediaries between the coil patterns of coupled inductors. These dielectric layers provide a controlled electromagnetic environment that stabilizes magnetic coupling by isolating the coils from direct substrate property variations while maintaining the necessary magnetic interaction through the layered structure
Solution Approach 2:
By arranging coil patterns on different dielectric layers in the vertical dimension rather than adjacent positions in the horizontal plane, the patent reduces sensitivity to substrate property variations. The vertical stacking configuration maintains magnetic coupling while minimizing the impact of lateral substrate inhomogeneities
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 stable attenuation and cross-isolation characteristics by minimizing variations in magnetic coupling, maintaining high isolation between filters across different frequency bands.
Implementation Method 1
a third coil pattern provided on the first dielectric layer and magnetically coupled to the first coil pattern
Data Source
AI summary
A multiplexer includes a transmission filter and a reception filter connected to a common terminal, a first inductor connected to the common terminal, and a multilayer substrate on which the transmission filter and the reception filter are mounted and which includes dielectric layers. The transmission filter includes a parallel-arm resonator connected to a path between the common terminal and a transmission terminal and a parallel-arm terminal, and a second inductor connected to the parallel-arm terminal and ground. The first inductor includes a first coil pattern on a first dielectric layer and a second coil pattern on a second dielectric layer. The second inductor includes a third coil pattern on the first dielectric layer and that is magnetically coupled to the first coil pattern. The inductance value of the second coil pattern is greater than that of the first coil pattern.