My response was incomplete. As I understand it reverse crosstalk will reach
some maximum magnitude and then level off. Achieving this maximum magnitude is
a function of both coupled length and rise time, hence the sensitivity to
frequency.
Conrad
From: Conrad Herse <herse@xxxxxxxxxxxxx>
To: "scott@xxxxxxxxxxxxx" <scott@xxxxxxxxxxxxx>; Boris Bakshan
<bbakshan@xxxxxxxxx>
Cc: "si-list@xxxxxxxxxxxxx" <si-list@xxxxxxxxxxxxx>
Sent: Thursday, June 18, 2015 5:44 PM
Subject: [SI-LIST] Re: NEXT vs. Frequency
Does rise time not also effect the *duration* of reverse crosstalk and NEXT?
Conrad
   From: Scott McMorrow <scott@xxxxxxxxxxxxx>
To: Boris Bakshan <bbakshan@xxxxxxxxx>
Cc: "si-list@xxxxxxxxxxxxx" <si-list@xxxxxxxxxxxxx>
Sent: Thursday, June 18, 2015 4:01 PM
Subject: [SI-LIST] Re: NEXT vs. Frequency
Â
You are mixing up NEXT with Reverse Crosstalk, and FEXT with Forward
Crosstalk
Reverse and Forward crosstalk are traveling waves the propagate on coupled
conductor in the forward and reverse directions.
NEXT and FEXT are the measurements made at the near end and far end sides
of the victim interconnect. NEXT is subject to discontinuities in
interconnect, including imperfect termination at the near and far ports.
These discontinuities give rise to frequency dependent variations in NEXT.
Scott McMorrow
Consultant - R&D
Teraspeed Consulting - A Division of Samtec
16 Stormy Brook Rd
Falmouth, ME 04105
(401) 284-1827 Business
http://www.teraspeed.com
On Thu, Jun 18, 2015 at 4:46 PM, Boris Bakshan <bbakshan@xxxxxxxxx> wrote:
Hello experts!
It is well known that NEXT coefficient is dictated by the properties of the
interconnect (mutual capacitance and inductance between the two
interacting lines). I do not see why is it that NEXT should change with
respect to frequency?
With FEXT, since we have rise time taken into account then the frequency
dependence is more trivial.
What am I missing with NEXT?
Thanks,
Boris.
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