From 2cfcda7ac04b9f11f04034dc9d939b0be511862a Mon Sep 17 00:00:00 2001
From: Claudio Fritsche <claudio.fritsche@gmail.com>
Date: Wed, 12 Feb 2025 10:57:45 +0100
Subject: [PATCH] vault backup: 2025-02-12 10:57:45

---
 .obsidian/workspace.json       | 22 ++++++++++++++++++----
 Temporary/PCB Design Review.md | 15 +++++++++++++++
 2 files changed, 33 insertions(+), 4 deletions(-)
 create mode 100644 Temporary/PCB Design Review.md

diff --git a/.obsidian/workspace.json b/.obsidian/workspace.json
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@@ -313,9 +313,23 @@
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@@ -328,10 +342,11 @@
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@@ -365,7 +380,6 @@
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diff --git a/Temporary/PCB Design Review.md b/Temporary/PCB Design Review.md
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+---
+title: PCB Design Review
+created_date: 2025-02-12
+updated_date: 2025-02-12
+aliases:
+tags:
+---
+# PCB Design Review
+
+## Rise Time vs Length
+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):
+First lets calculate the wave length in free space:
+$$\lambda = \frac{c}{f} = \frac{3*10^{8}}{100*10^6} = 3m$$
+In a PCB you can take roughly $\frac{\lambda}{2}$ as the wavelength, which would be $1.5m$. 
+One sixth of this results in roughly $25cm$.
\ No newline at end of file