Best Practices for Differential Pair Signal Transitioning
I'm in the midst of transitioning a differential pair between layers on my PCB design, and I want to make sure I'm following the best practices to maintain signal integrity. Could you share some industry insights on how to do this effectively, considering factors like via placement and impedance matching?
Solution:Jump to solution
Considering a dielectric constant of about 4, the signal propagation speed is about 150.000.000 m/s. The cycle of your clock is 5 ns. The distance the signal travels during a single clock cycle is 150.000.000 m/s x 5 ns = 750 mm. If your transmission channel is shorter than 30 mm, I recommend focusing on other things than this transmission channel.
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What is the maximal frequency your transmission channel will carry? What is your PCB stack-up? How long is your transmission channel?
Max Frequency = 200MHz, stackup = sig,gnd,gnd,sig , length = less than 30mm
Achieving this at an optimal level will involve asking your fab house for assistance. Guiding you in getting the right impedence value based on your stackup plan. For better signal Integrity.
Solution
Considering a dielectric constant of about 4, the signal propagation speed is about 150.000.000 m/s. The cycle of your clock is 5 ns. The distance the signal travels during a single clock cycle is 150.000.000 m/s x 5 ns = 750 mm. If your transmission channel is shorter than 30 mm, I recommend focusing on other things than this transmission channel.