# SPOT THE FLAW: This trace is carrying more than just a signal

**URL:** https://sierraconnect.protoexpress.com/t/spot-the-flaw-this-trace-is-carrying-more-than-just-a-signal/4335
**Category:** PCB Design Challenges
**Created:** [August 5, 2026, 2:29pm UTC](https://sierraconnect.protoexpress.com/t/spot-the-flaw-this-trace-is-carrying-more-than-just-a-signal/4335 "2026-08-05T14:29:28Z")
**Posts on this page:** 3
**Page:** 1

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### Author: ![lucy.sierracircuits](https://sea2.discourse-cdn.com/sierraconnect/user_avatar/sierraconnect.protoexpress.com/lucy.sierracircuits/32/8_2.png) [@lucy.sierracircuits](https://sierraconnect.protoexpress.com/u/lucy.sierracircuits)
#### Post date: [August 5, 2026, 2:29pm UTC](https://sierraconnect.protoexpress.com/t/spot-the-flaw-this-trace-is-carrying-more-than-just-a-signal/4335/1 "2026-08-05T14:29:28Z")

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![8-5_Uncontrolled impedance trace](https://global.discourse-cdn.com/sierraconnect/original/1X/215f4d8e823ddff1131216d4d7b8e5af54ac09b5.png)

Answer on Friday…

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### Author: ![aryanbrb](https://avatars.discourse-cdn.com/v4/letter/a/e0b2c6/32.png) [@aryanbrb](https://sierraconnect.protoexpress.com/u/aryanbrb)
#### Post date: [August 7, 2026, 5:19am UTC](https://sierraconnect.protoexpress.com/t/spot-the-flaw-this-trace-is-carrying-more-than-just-a-signal/4335/2 "2026-08-07T05:19:52Z")

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The diff pair does not seem to have a reference ground plane, so it’s carrying noise/jitter along with a signal.

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### Author: ![atar.mittal](https://sea2.discourse-cdn.com/sierraconnect/user_avatar/sierraconnect.protoexpress.com/atar.mittal/32/49_2.png) [@atar.mittal](https://sierraconnect.protoexpress.com/u/atar.mittal)
#### Post date: [August 7, 2026, 8:27pm UTC](https://sierraconnect.protoexpress.com/t/spot-the-flaw-this-trace-is-carrying-more-than-just-a-signal/4335/3 "2026-08-07T20:27:24Z")

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Great catch, @aryanbrb. The lack of a clear ref plane is definitely something to be concerned about, as it can lead to poor return current paths and increased EMI.

Let’s also point out this other flaw: the **uncontrolled impedance trace**. Without a properly defined impedance, high-speed signals can suffer from reflections, SI issues, and unreliable performance.

Thanks for pointing out another important issue, @aryanbrb it’s a good reminder that there can be more than one thing to spot in a PCB layout!