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1. minute (mntmn@mastodon.social)'s status on Tuesday, 23-Jul-2024 01:17:43 JST minute

   > Contrary to popular belief, differential signalling does not affect noise cancellation

   • minute (mntmn@mastodon.social)'s status on Tuesday, 23-Jul-2024 01:21:18 JST minute

     in reply to

     > There exists great confusion as to what constitutes a balanced interface

   • minute (mntmn@mastodon.social)'s status on Tuesday, 23-Jul-2024 01:45:03 JST minute

     in reply to

     • niconiconi

     @niconiconi yes, this is also how i understand it. so i'm wondering if intra-pair skew has a bigger bad effect on PCIe 3.0 signal integrity than the diff pair impedance. it's somehow hard to find some good material on the effect of different impedance values on diff signalling integrity.

   • niconiconi (niconiconi@mk.absturztau.be)'s status on Tuesday, 23-Jul-2024 01:45:05 JST niconiconi

     in reply to

     @mntmn@mastodon.social One gets noise cancellation just by terminating V+ and V- to the same impedance, instead of terminating one side to circuit ground. External noise induces roughly the same noise voltages on both lines, so noise is rejected. It works regardless of whether the signal is symmetric or not. This is called "balanced" signaling. "Differential" signaling is a special case of balanced signaling in which the voltages on both lines are also equal and opposite. My understanding, if I got it right, is that balanced signaling is sufficient for low-noise audio, so it's wrong to say this noise suppression comes from differential "signaling" - it does not, it comes from the termination impedance. But for high-speed digital interfaces, I think differential signaling is still needed to suppress radiated EMI.