Multicore Transmission Line Layout for Signal Isolation in Tight Space
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Solution Overview
Problem
Existing multicore transmission lines face challenges in reducing size in both thickness and width directions as the number of signal lines increases, making it difficult to integrate them into devices with limited housing sizes while maintaining effective isolation and reducing interference.
Innovation Solution
A transmission line configuration with a conductor pattern and insulating substrates, where signal lines are parallel and separated by ground connection conductors, reducing width and thickness without interposing ground conductors between signal lines, ensuring isolation through frequency differences and ground connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the number of signal lines is increased by spacing them apart or adding ground conductors, then isolation between signal lines is improved, but the size of the transmission line in thickness or width direction increases
Solution Approach 1:
The patent transitions from two-dimensional spacing (width direction) to three-dimensional stacking (thickness direction) by laminating multiple insulating substrates with conductor patterns at different positions. This allows signal lines to be isolated vertically across layers rather than horizontally within a single layer, achieving both compact width and effective isolation.
Solution Approach 2:
The patent embeds ground conductors within the laminated insulating substrate structure, nesting them between signal lines in the thickness direction. This nested arrangement provides isolation between adjacent signal lines without increasing the overall width, as ground conductors are integrated into the multi-layer construction rather than added as separate lateral elements.
2Reliability
If adjacent signal lines are disposed at different positions in lamination direction to increase distance, then isolation is enhanced, but the number of laminated insulating substrates increases and total thickness increases
Solution Approach 1:
The patent combines multiple functions into the ground conductor layer: it serves as both the isolation barrier between signal lines and the reference plane for impedance control. By merging these functions into a single conductor pattern on the insulating substrate, the design achieves effective isolation without requiring additional layers that would increase thickness.
Solution Approach 2:
The patent optimizes the thickness of insulating substrates and the positioning of conductor patterns to achieve effective isolation with minimal total thickness. By carefully controlling parameters such as substrate thickness, conductor trace width, and spacing, the design achieves the required isolation performance while minimizing the overall thickness of the laminated structure.
3Reliability
If ground conductors are disposed between adjacent signal lines to secure isolation, then isolation is improved, but the width of the transmission line increases
Solution Approach 1:
The patent moves the isolation function from the width dimension to the thickness dimension by placing ground conductors on separate laminated layers rather than between signal lines in the same layer. This vertical separation achieves effective isolation while maintaining a compact width, as the ground conductors are positioned in the thickness direction through lamination rather than expanding the width horizontally.
Data Source
AI summary
A transmission line includes first, second, and third signal lines defining a parallel portion. No conductor connecting the first ground conductor and the second ground conductor is between the first signal line and the second signal line, and the first signal line is closer to the ground connection conductor than the second signal line. A closest frequency difference between a fundamental wave of one of the first signal and the second signal and a fundamental wave or a higher harmonic wave of the other of the first signal and the second signal is equal to or larger than a closest frequency difference between a fundamental wave of one of the first signal and the third signal and a fundamental wave or a higher harmonic wave of the other of the first signal and the third signal.