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I'm working on an analogue audio, video and sync board for my Dreamcast. Something I've been wondering about is the tolerance for analogue video, specifically RGB, in regards to the delta for trace length.

In my case my total Red and Blue traces are 61.382mm and my total Green trace is 55.964mm, and all three have a 220µF electrolytic capacitor (C1, C2 and C3) around the middle of their traces. The max voltage through the traces is 0.7VAC, they operate at 14MHz, my trace width is 0.414mm (for 75 ohm impedance) and the distance between them is around 5.50mm. Will that 5.418mm delta cause problems? Because I'm having a tough time exactly matching Green with the other traces.

This is my current circuit, in case it helps.

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  • \$\begingroup\$ With a 20-odd meter wavelength, do you really think a few mm one way or another would make even the slightest difference? Compared to the cables you plug in and the wiring in the monitor a few mm on a trace would be swamped by other length differences. \$\endgroup\$ – Majenko May 27 '18 at 9:26
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    \$\begingroup\$ On FR-4 (average stuff, dielectric constant about 4), that length mismatch amounts to 36 picoseconds. I strongly doubt that will be an issue. \$\endgroup\$ – Peter Smith May 27 '18 at 14:56
  • \$\begingroup\$ @Peter Smith. Thank you very much. I'm learning the ropes of PCB design since I'm out of school now so I really appreciate the input from you and Majenko. Due to the wavelength of my audio waveforms I'm fairly certain that the delta of my audio traces won't matter either in this applications. Again, thank you. \$\endgroup\$ – residentevilman64 May 27 '18 at 17:06

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