Re: [SI-LIST] : Measuring Ground Noise

Larry Smith (ldsmith@lisboa.eng.sun.com)
Tue, 23 Jun 1998 08:14:33 -0700 (PDT)

> Can anybody suggest a good way of measuring Noise on GND around
> devices?
>
> Thanks,
> Mark Nass

Measure Gnd noise with respect to Vdd... At signal integrity
frequencies, there is no such thing as an ideal reference point. All
signals and noises are differential (something with respect to
something else). A high bandwidth single ended probe with short (1/4
inch, if possible) leads for both Vdd and ground will work well. You
can measure Vdd WRT Gnd as well as any signal WRT ground. This is
excactly what a device located at that position will see and respond
to.

regards,
Larry D Smith
Sun Microsystems

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