[SI-LIST] Re: Series termination
- From: "Patrick Zilaro" <pzilaro@xxxxxxxxxxxx>
- To: vinayak.agrawal@xxxxxx, si-list@xxxxxxxxxxxxx
- Date: Mon, 27 Dec 2004 14:06:38 -0800
Are you planning on using a "current steering" approach for your driver? =
If
so, I don't think I've ever seen series termination on the outputs, . . =
.
only parallel termination.
If you want to add real resistance to your output impedance, in addition =
to
the impedance of the transistors switching, . . . most people place the
resistors on-chip in series with the current source (as opposed to in =
series
with the output pins).
Regards,
Patrick
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] =
On
Behalf Of Vinayak AGRAWAL
Sent: Monday, December 27, 2004 3:49 AM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Series termination
Hi
I am designing a transceiver that will use series termination. The IO is =
a differential driver, so while one pin will be connected to high=20
voltage (external pin) through a series resistor of 50ohms, the other=20
will be connected to gnd (and the connectivity switches to toggle the=20
output) the same way.
when I started design I thought it should be good enough to terminate in =
this way, because I had seen many single-ended (as opposed to=20
differential) drivers doing the same. However now I'm worried whether=20
the differential termination will be good enough for a 100ohm =
termination.
Specifically I'm concerned about the return path for the current. As I=20
see it, it is something like: into the negative pin, through 50ohm, gnd, =
gnd-vdd coupling, vdd, 50ohms resistor, positive going pin. I doubt=20
whether gnd-vdd coupling will be good enough for high speed data=20
transfer (300-6000Mbps). On the other hand I believe similar issues=20
should come for single-ended drivers.
Can someone point to any reading material. Also any criticisms of the=20
approach are welcome.
Regards
Vinayak
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List FAQ wiki page is located at:
http://si-list.org/wiki/wiki.pl?Si-List_FAQ
List technical documents are available at:
http://www.si-list.org
List archives are viewable at: =20
//www.freelists.org/archives/si-list
or at our remote archives:
http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
=20
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List FAQ wiki page is located at:
http://si-list.org/wiki/wiki.pl?Si-List_FAQ
List technical documents are available at:
http://www.si-list.org
List archives are viewable at:
//www.freelists.org/archives/si-list
or at our remote archives:
http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
Other related posts:
