[SI-LIST] Re: Trace Width @ 3Gb/s
- From: "Mustansir Fanaswalla" <mustansi@xxxxxxxx>
- To: <hassan@xxxxxxxx>, "Rudy Sterner" <rsterner@xxxxxxxx>,<si-list@xxxxxxxxxxxxx>
- Date: Mon, 10 Jun 2002 09:19:17 -0700
Hi,
There is significant attenuation of the signal, consequently leading to bit
errors.
Your comments indicate that the narrow traces very well could be the cause.
Thanks
Mustansir
-x-x-x-x-x-x-x-x-x-x-x-x-x-x-x-x-
Mustansir Fanaswalla
LSI Logic Corporation
-x-x-x-x-x-x-x-x-x-x-x-x-x-x-x-x-
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx
[mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of Hassan O. Ali
Sent: Monday, June 10, 2002 9:01 AM
To: Rudy Sterner; si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: Trace Width @ 3Gb/s
Rudy,
Could you be specific on the kind of issues you have with the SerDes link?
That way you
can receive suggestions that are more specific to your situation.
Yes, 4-mil tracks can be a problem. With those tracks, in a microstrip
format you need
less than 3-mil height to achieve close to 50-ohm single-ended line
impedance (which
might be your goal). With that small height and at that data rate, component
pads
(especially AC-coupling cap pads, if you have any) start to dominate heavily
causing
tremendous impedance discontinuities.
In addition, narrow tracks give rise to higher loss - both line-loss and
reflection loss
due to pronounced discontinuities at various locations (the connector
launch-point is
one of the most important ones).
Regards.
Hassan.
On Jun 10, "Rudy Sterner" <rsterner@xxxxxxxx> wrote:
>
> Hello,
>
> We have some issues with a SerDes which we think
> may be related to the trace width on the serial line. The
> serial port is a differential pair passing data at 3 Gb/s.
> The trace width is 4 mils. Length is approximately 5 inches.
> The differential impedance is 100 Ohms. Other information
> which may be of use is the board material is FR-4 with an
> Er of 3.9. It is specified at this data rate.
>
> My question is: Are the traces too narrow? Should I
> expect better performance with 8-mil traces?
>
> Thank You
>
> Rudy Sterner
> LSI Logic
>
------------------------------------------------------------------
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 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
------------------------------------------------------------------
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 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:
