15 lines
626 B
Markdown
15 lines
626 B
Markdown
---
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title: PCB Design Review
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created_date: 2025-02-12
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updated_date: 2025-02-12
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aliases:
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tags:
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---
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# PCB Design Review
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## Rise Time vs Length
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The rule of thumb is that a track length shall be shorter than 1/6th of the rise time. According to [this comment](https://electronics.stackexchange.com/a/258992) the rule of thumb can be applied like this (example with 100MHz signal):
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First lets calculate the wave length in free space:
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$$\lambda = \frac{c}{f} = \frac{3*10^{8}}{100*10^6} = 3m$$
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In a PCB you can take roughly $\frac{\lambda}{2}$ as the wavelength, which would be $1.5m$.
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One sixth of this results in roughly $25cm$. |