via or longer trace, which one you prefer
altay , 07-16-2018, 08:46 PM
Hi,
On my project I faced the case to choose between longer path or use VIA for high speed interface (SATA in my case)
for similar high speed interfaces such as GigE,SATA,PCIE,DDR Ram,etc. what would you prefer?
PS: I now its recommended no to make a via for some high speed interfaces but its recommendation and I am not sure what would be consequences if violated
Thanks
On my project I faced the case to choose between longer path or use VIA for high speed interface (SATA in my case)
for similar high speed interfaces such as GigE,SATA,PCIE,DDR Ram,etc. what would you prefer?
PS: I now its recommended no to make a via for some high speed interfaces but its recommendation and I am not sure what would be consequences if violated
Thanks
Paul van Avesaath , 07-17-2018, 06:16 AM
A via is no problem in your transmission line, I do not know your layer stack but try to keep via stubs to a minimum.. most cases it will be top to bottom, that works fine!
make your via as transparent as possible by adding GND via's around it (and keep those identical and same distance to all sides). you can calculate Via properties with Saturn PCB calculator (its free) and then you know how big your clearence around the Via should be.
shorter trace with via is recommended..
make your via as transparent as possible by adding GND via's around it (and keep those identical and same distance to all sides). you can calculate Via properties with Saturn PCB calculator (its free) and then you know how big your clearence around the Via should be.
shorter trace with via is recommended..
robertferanec , 07-18-2018, 09:03 AM
Often I route high speed signals inside PCB (because of EMC and EMI). So it may depend on your stackup and product (industrial of office use).
If I would go inside of PCB, I may try to use as much as possible from the length of VIA, so there is minimum stub in VIA. However routing the whole track on TOP or BOTTOM layer is also fine (I do it this way for very high speed signals and FPGA / CPU boards where I do not want to use VIAs or I do not want to have stub in VIA). And often these tracks are long - no problem.
If I would go inside of PCB, I may try to use as much as possible from the length of VIA, so there is minimum stub in VIA. However routing the whole track on TOP or BOTTOM layer is also fine (I do it this way for very high speed signals and FPGA / CPU boards where I do not want to use VIAs or I do not want to have stub in VIA). And often these tracks are long - no problem.
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