Asymmetric Multi-Point Wiring for Printed Circuit Boards
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Solution Overview
Problem
Existing multi-point wiring configurations in printed circuit boards for memory devices face challenges in maintaining signal quality due to undesired reflection and waveform distortion, which complicates the arrangement of components and restricts the total wiring length, making it difficult to achieve high-speed and high-capacity performance.
Innovation Solution
The implementation of a multi-point wiring configuration with non-equal spacing pitches between branch points, where the distance from the memory controller to the first branch is longer than the distances between subsequent branches, effectively reducing signal reflections and ensuring a wider voltage margin for noise resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If equal spacing pitches are used between branch points in multi-point wiring, then arrangement of components is simplified, but signal reflection and waveform distortion increase
Solution Approach 1:
The patent applies asymmetry by setting different spacing pitches between branch points in the multi-point wiring. Specifically, the first spacing pitch from the memory controller to the first branch point is made longer than the second spacing pitch between subsequent branch points. This asymmetric configuration reduces simultaneous superimposition of ring-back and capacity reflection components, thereby improving signal quality and reducing waveform distortion while maintaining component arrangement flexibility.
2Reliability
If distance from memory controller to first branch is increased to reduce reflection, then signal quality improves, but total wiring length becomes excessively long
Solution Approach 1:
The patent applies parameter changes by optimizing the spacing pitches between branch points. The first spacing pitch is set to be longer than the second spacing pitch, creating a specific parameter relationship that reduces signal reflection. This parameter optimization allows the total wiring length to be controlled within specifications (e.g., 100mm for data strobe signals) while maintaining improved signal quality and reducing waveform distortion.
3Speed
If wiring length is reduced to meet specifications, then signal transmission speed improves, but voltage margin decreases making correct transmission difficult
Solution Approach 1:
The asymmetric spacing pitch configuration (first pitch longer than second pitch) creates optimal signal transmission conditions by reducing simultaneous superimposition of reflection components. This improves waveform quality and maintains adequate voltage margins even when wiring lengths are reduced to meet strict specifications, enabling correct signal transmission at high speeds.
Data Source
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AI summary
In a printed wiring board, one transmitting circuit and N (N is an integer of 3 or more) receiving circuits are coupled by a multi-point wiring. First to N-th branch points are provided in sequence in the multi-point wiring having one end coupled to the transmitting circuit. Wirings branched at the respective branch points are coupled to the respective receiving circuits. Here, a wiring length from a coupling point of the transmitting circuit to a first branch point is configured to be longer than a wiring length from the first branch point to the second branch point. Wiring lengths between the adjacent branch points at and after a second branch point are configured to be shorter than the wiring length from the first branch point to the second branch point.