cancel
Showing results for 
Show  only  | Search instead for 
Did you mean: 
wilsonteo
Visitor
Visitor
6,116 Views
Registered: ‎11-19-2009

Design Consideration for High Speed Signals

Hi,

 

I'm implementing a custom design FPGA board using Virtex-7 FPGA.

 

Using reference from the stackup on VC707, I realised that there are 3 different impedance control for this design. For example, PCIe 2.0 is likely using 85R differential impedance and LVDS clock are using 100R differential impedance.

 

Is there any documentation that stated the design consideration for using 80/85/100 differential impedance and what are the types of signals that need the impedance? Similarly for the single-ended signal using 40/50 ohms.

 

Also, for FMC connector, what are the considerations for length matching the HPC (LA, HA, HB) signals?

 

Thanks.

 

 

0 Kudos
Reply
2 Replies
kotir
Scholar
Scholar
6,112 Views
Registered: ‎02-03-2010

Hi,

 

Have a look at the             PCB.01#02 of the below link.

 

https://www.pcisig.com/specifications/pciexpress/technical_library/PCIeMotherboardChecklist1.0.doc

 

For 6 layer it is pointed as 100 Ohm and 8/10 layer boards are pointed to 85Ohm diff imp.

 

 

Regards,

KR

--------------------------------------------------​--------------------------------------------
Kindly note- Please mark the Answer as "Accept as solution" if information provided is helpful.

Give Kudos to a post which you think is helpful.
--------------------------------------------------​-------------------------------------------
0 Kudos
Reply
kotir
Scholar
Scholar
6,109 Views
Registered: ‎02-03-2010

Hi ,

 

Regarding the FMC board design.

I believe you should look at how it is done with existing cards.

 

http://www.xilinx.com/support/documentation/boards_and_kits/ug538.pdf - FMC XM101 card user guide.

 

http://www.xilinx.com/support/documentation/user_guides/ug483_7Series_PCB.pdf

 

Regards,

Koti Reddy

--------------------------------------------------​--------------------------------------------
Kindly note- Please mark the Answer as "Accept as solution" if information provided is helpful.

Give Kudos to a post which you think is helpful.
--------------------------------------------------​-------------------------------------------
0 Kudos
Reply