But several other things enter into the picture which at times are much more
significant than the mathematics of the scope bandwidth.
1) What type of probe does the unit have. If its bulky, like some of HP's
high freq. stuff, it may more suited to very
carefully setup lab situations where PCB space and clearances are not a
factor. As opposed to a .1in pitch(signal-gnd), low profile
active scope probe head.
2) Do you have test points on your proto-type PCB. If so, what are they.
1 pin headers, 2 pin headers, Mictors, SMA's?
3) Dependent upon (2) above, how do you plan to connect your scope probe
to these test points? How do you plan to connect your
scope ground to a ground point? The inductance and impedance of these
connections matter. Especially with rise times under 1ns.
The accuracy of the trace on the scope screen depends on the Scope, the
Probe and the connection to the PCB. If you are early enough in
your design cycle, I would take some time to review all of the above. Nick
> From: Chris Bobek[SMTP:firstname.lastname@example.org]
> Sent: Thursday, May 20, 1999 12:32 PM
> To: email@example.com
> Subject: [SI-LIST] : What speed scope should I consider?
> We are designing an SBC with a processor speed of 266MHz and bus speed of
> 66MHz. There are different logic families used on the board, some CMOS,
> some TTL -- just standard stuff (no ECL or GTL, etc.).
> Based upon that general scenerio, what bandwidth scope should be adequate
> for doing SI analysis on our board? We are currently looking at a scope
> with a 1.5GHz bandwidth (8GHz sampling rate). This seems sufficient, but
> would like other opinions...
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