Stacked Multiplexer PCB Layout Without Through Vias
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Solution Overview
Problem
Traditional multiplexers have complex signal wiring structures that lead to impedance mismatch and transmission interference due to the use of numerous through vias, resulting in poor signal transmission quality.
Innovation Solution
A multiplexer design with a stacked board structure that employs non-contact signal coupling between metal layers, utilizing the same wiring structure for signal transmission paths and filters, reducing the need for through vias and minimizing impedance mismatch and interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If through vias are used to transmit signals between different layers, then signal transmission can be achieved, but impedance mismatch and transmission interference occur resulting in poor signal transmission quality
Solution Approach 1:
The patent transitions from vertical signal transmission through vias to horizontal signal transmission along metal layers. By routing signals along the surface of metal layers and using capacitive coupling for inter-layer communication, the design eliminates the need for through vias and resolves the impedance mismatch and interference problems associated with vertical via transmission.
Solution Approach 2:
The patent replaces the physical mechanical connection of through vias with electromagnetic field-based capacitive coupling. Instead of direct conductive paths through the substrate, signals are transmitted via electric fields between adjacent metal layers, eliminating the harmful mechanical drilling and plating processes that create impedance discontinuities.
2Device complexity
If a complex signal wiring structure with many through vias is used, then signal transmission between layers is possible, but the structure becomes complex and prone to transmission interference
Solution Approach 1:
The patent redistributes signal routing from the vertical dimension (through vias) to the horizontal dimension (along metal layers). This dimensional shift simplifies the wiring structure by eliminating the need for complex via arrangements while maintaining signal transmission capability through capacitive coupling between layers.
Solution Approach 2:
The patent divides the signal transmission function into separate components: horizontal signal routing along metal layers and vertical signal coupling through capacitive interfaces. This segmentation allows each component to be optimized independently, reducing overall system complexity while improving signal quality.
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 stacked board structure achieves improved signal transmission quality by eliminating impedance mismatch and interference, ensuring efficient transmission of communication signals across different frequency bands.
Implementation Method 1
The signal coupling between the at least one first signal transmission path structure and the at least one filter structure is performed in a non-contact manner
Implementation Method 2
The signal coupling between the at least one filter structure and the at least one second signal transmission path structure is performed in a non-contact manner
Data Source
AI summary
A multiplexer includes a first circuit board, a second circuit board, and a third circuit board. The first circuit board includes a first metal layer, a first substrate layer, and a second metal layer sequentially stacked along a first direction. The second circuit board includes a third metal layer, a second substrate layer, and a fourth metal layer sequentially stacked along the first direction. The third circuit board includes a fifth metal layer, a third substrate layer, and a sixth metal layer sequentially stacked along the first direction. The second and third metal layer have same wiring structure, and the second metal layer connects to the third metal layer to form a first signal transmission path structure and a filter structure. The fourth and fifth metal layer have same wiring structure, and the fourth metal layer connects to the fifth metal layer to form a second signal transmission path structure.