Multilayer PCB Differential Signal Synchronization via Anti-Pad Capacitance
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Solution Overview
Problem
Conventional methods for designing multilayer printed boards with differential signal wiring require labor-intensive adjustments of via shapes and land diameters to achieve synchronized signal transmission, leading to inefficiencies in electric length adjustments.
Innovation Solution
The implementation of a multilayer printed board structure with equal-sized circular vias and pads, where the anti-pad radius is varied to adjust capacitance between signal vias and constant potential layers, allowing for equalization of signal propagation times across different signal lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the shapes of vias or lands are made different to adjust electric lengths of differential signal wiring, then signal synchronization is improved, but design complexity and labor hours increase
Solution Approach 1:
The patent applies local quality by varying the anti-pad radius specifically around vias on one layer of the differential pair, while keeping other via parameters uniform. This localized modification adjusts the electric length of specific via segments without requiring changes to all via structures throughout the board, thus achieving signal synchronization while minimizing design complexity.
Solution Approach 2:
The patent changes the parameter of anti-pad radius to adjust the capacitance and electric length of differential signal vias. By modifying this specific geometric parameter rather than changing via shapes or land configurations, the patent achieves precise control over signal propagation delay while maintaining manufacturing simplicity and design efficiency.
2Duration of action of moving object
If via shapes are altered from circular to elliptical to adjust electric lengths, then signal propagation time is improved, but manufacturing complexity increases
Solution Approach 1:
The patent modifies the anti-pad radius parameter instead of changing the via shape from circular to elliptical. This approach achieves the same effect of adjusting signal propagation time through capacitance modification, while maintaining circular via shapes that are simpler and more cost-effective to manufacture using standard drilling and plating processes.
3Manufacturing precision
If land diameters of vias are made different to adjust electric lengths, then signal synchronization is improved, but design time and complexity increase
Solution Approach 1:
The patent changes the anti-pad radius parameter to adjust electric lengths, providing a more straightforward and automated approach compared to varying land diameters. This parameter modification can be easily implemented in PCB design software, reducing manual calculation and iteration time, thus decreasing design labor hours while achieving precise signal synchronization.
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 approach simplifies the design process by maintaining consistent via and pad diameters, effectively adjusting electric lengths and ensuring synchronized signal arrival times without increasing operational steps or wiring regions.
Implementation Method 1
Distances between peripheries of the pad and the constant potential layer in each of the wiring layers are set so that a capacitance between the constant potential layers and a signal via included in one of the signal lines constituting the differential signal wiring, which has a longer route from a transmission end to a reception end, is smaller than a capacitance between the constant potential layers and another signal via included in the other one of the signal lines.
Data Source
AI summary
According to one embodiment, a multilayer printed board includes an insulating substrate, a differential signal wiring, and anti-pad regions. Distances between peripheries of the pad and a constant potential layer in each of the wiring layers are set so that a capacitance between the constant potential layers and a signal via included in a signal line constituting the differential signal wiring, which has a longer route from a transmission end to a reception end, is smaller than a capacitance between the constant potential layers and another signal via included in the other signal line.