[SI-LIST] Re: crosstalk

  • From: "Massoud Shakeri" <massoud@xxxxxxxxxxx>
  • To: <si-list@xxxxxxxxxxxxx>
  • Date: Mon, 8 Aug 2011 23:08:17 -0700

Brian,
If the length of these two tracks is 1 or 2 inches at 20mils distance,
usually it should not be a problem, because SDA is around 1 Mbps and orders
of magnitude less than SERDES. But there are some issues that you need to
consider:
   - Say you have 300 mV budget for crosstalk on SERDES, and crosstalks from
other lines are already close to the budget, so passing SDA line close to
SERDES may cause crosstalk to surpass the budget, and you need to change
something to bring it lower.
  - Crosstalk from SERDES on SDA usually cannot make SDA to malfunction. But
more important issue is SDA line can be a good antenna for 10GB/s signal if
it's on top or bottom layer, and you may have more trouble with EMI/EMC.
  - For an exact answer you need to do a post-routing simulation, for
example with Hyperlynx. It does not take much time to do that. You can
perform simulation on a few nets including SERDES and status lines close to
them.

Massoud Shakeri


-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On
Behalf Of tianluchuan2005
Sent: Monday, August 08, 2011 6:12 PM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] crosstalk

I have a question need your help.

There is a via, the net is SDA of I2C, is close to 10Gb/s SERDES, the
distance is about only 20mils.
And I am afraid if there is the crosstalk between the SDA and SERDES.
I don't know if the distance is safe, or the SDA have no influence to SERDES
?

Thanks !


-Brian Tian


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