Timeline for How do PCB vias affect signal quality?
Current License: CC BY-SA 4.0
17 events
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| Oct 8, 2019 at 5:47 | history | edited | Voltage Spike♦ |
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| Apr 12, 2019 at 15:57 | comment | added | DKNguyen | 20ns risetime equates to a bandwidth of approximately 17.5MHz. The rough estimate is BW = 0.35/(risetime). | |
| Apr 12, 2019 at 15:42 | vote | accept | Jeff Wahaus | ||
| Apr 12, 2019 at 15:40 | history | edited | Jeff Wahaus | CC BY-SA 4.0 |
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| Apr 11, 2019 at 23:50 | comment | added | Nick Alexeev | @ChrisStratton I agree with you that 4MHz isn't high speed as high speed comes these days. For the sake of completeness, many signal integrity issues are driven by raise time, rather than fundamental frequency. A 4MHz clock may have a 20ns raise time. | |
| Apr 11, 2019 at 21:00 | history | tweeted | twitter.com/StackElectronix/status/1116445898605776896 | ||
| Apr 11, 2019 at 18:50 | history | became hot network question | |||
| Apr 11, 2019 at 18:46 | answer | added | Justme | timeline score: 3 | |
| Apr 11, 2019 at 16:43 | comment | added | analogsystemsrf | for a start, view each via as 1 nanoHenry inductance in series with a transmission line. Then you can refine this model. | |
| Apr 11, 2019 at 16:38 | answer | added | Voltage Spike♦ | timeline score: 4 | |
| Apr 11, 2019 at 16:30 | comment | added | TemeV | With two layer board there typically isn't a solid ground plane so the trace impedance is not constant anyway. Thus vias make little difference. And at least they don't cause (significant amount of) noise. Also 4 MHz is not high speed as mentioned in other comments. | |
| Apr 11, 2019 at 16:28 | answer | added | JYelton | timeline score: 6 | |
| Apr 11, 2019 at 16:28 | answer | added | D.A.S. | timeline score: 2 | |
| Apr 11, 2019 at 16:20 | comment | added | Chris Stratton | A 4 MHz SPI bus is hardly "high speed" today - you do need to think about signal integrity but sane via usage should not be an issue. You should not need five vias to accomplish a 5cm run - did you let an autorouter run wild? For boards someone asking your question would be making, you probably should be manually routing. The "noise" you are measuring is likely a result of how you are measuring, there probably is some overshoot and ringing, but it's not clear you are measuring that. | |
| Apr 11, 2019 at 16:16 | comment | added | ratchet freak | If you imagine the side view of a trace through a via, how would you expect that shape to affect the signal? | |
| Apr 11, 2019 at 16:10 | history | edited | JYelton | CC BY-SA 4.0 |
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| Apr 11, 2019 at 16:09 | history | asked | Jeff Wahaus | CC BY-SA 4.0 |