[SI-LIST] Re: How to Measure Ground Noise
- From: "Joe Paul" <joepaulm@xxxxxxxxxxxxx>
- To: si-list@xxxxxxxxxxxxx
- Date: Wed, 6 Apr 2005 22:27:09 +0550
The method you described, measures the potential difference between the GND
of CRO and your GND.
(If you consider the GND of CRO as a Good reference)
If you have a differential probe you can try these with its gnd connected to
one of the measuring
points (you may use 2 single ended probes with their gnds clipped together, but
have more loop
length/inductance which gather more noise) You may measure Ground Bounce as
1)
Difference between the potential of GNDs at point you are interested and at the
power source (o/p
of Regulator or Power entry point of card which ever is applicable)
2)
Difference between the potential of GNDs at points.
Eg: GNDs at Source Buufer and GND at load buffer
The second one seems more relevant to me.
Refer High-Speed Digital Design, by Howard Johnson for better understanding
Joe Paul
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On
Behalf Of ospyng
Sent: Wednesday, April 06, 2005 11:53 AM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] How to Measure Ground Noise
hi,
I was taught to measure ground noise, by having the ground of the probe connect
to ground TP of the
board and the tip of the probe measuring the same TP.
is this the correct where? and Why?
is it because of the ground cable (3 inch) cause a loop, therefore the
reference and the tip of the
probe has a different voltage?
thanks
pyng
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