[SI-LIST] Re: How to connect Chassis ground to DGND
- From: "Grasso, Charles" <Charles.Grasso@xxxxxxxxxxxx>
- To: "'cchalmers@xxxxxxxxxxx'" <cchalmers@xxxxxxxxxxx>,"'si-list@xxxxxxxxxxxxx'" <si-list@xxxxxxxxxxxxx>
- Date: Fri, 27 Feb 2004 09:48:09 -0700
Typically you want to make that connection as robust as possible - after all
it (the impedance of that connection) becomes the excitation source for the
antenna currents on the cable shield. Of course the amount of antenna
current on the shield depends on the system design - the better that is
accomplished the impedance of that connection is less of an issue
Best Regards
Charles Grasso
Senior Compliance Engineer
Echostar Communications Corp.
Tel: 303-706-5467
Fax: 303-799-6222
Cell: 303-204-2974
Email: charles.grasso@xxxxxxxxxxxx;
Email Alternate: chasgrasso@xxxxxxxx
-----Original Message-----
From: Chris Chalmers [mailto:cchalmers@xxxxxxxxxxx]
Sent: Friday, February 27, 2004 3:30 AM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] How to connect Chassis ground to DGND
Folks,
Sorry to bring this old chestnut back to life. I have a question in
relation
to Dr Howard Johnson's note on radiated ground noise (on sigcon website).
I have a board that has a graphics DVI connector on it. I have connected
the grounds on the
connector to DGND on my board. I have also put a chassis ground layer in
my stackup
next to a solid ground layer. From Dr J's note, I have connected DGND on
my board
to the chassis layer at the DVI connector. This is to pin the DGND to the
same potential as the
chassis ground (which should not be bobbing about like the DGND) at this
point so that
noise on my DGND is not radiated on to the graphics cable. Currently I
have made the
connection between CHGND and DGND with an 0603 resistor. Is this OK or
should
I make multiple connections with vias instead of the resistor?
I have a second question as well if I may. I have a connector at the
other end of the
board which I want to implement a similiar strategy. Can I do exactly the
same at this
other connector or will I start to have problems with ground loops between
the two.
Thanks in advance
Chris
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