Re: What scope freq do I need?

From: Robert Lacoste (see-www-alciom-com-for-email-adress)
Date: 07/12/04 

Date: Mon, 12 Jul 2004 15:12:31 +0200

"alpha_uma" <none_such@home.com> a écrit dans le message de
news:ukoIc.74910$P7.18105@pd7tw3no...
> To look at the digital signals/waveforms of a modern CPU, say, f = 1GHz
> Pentium to be specific, how "slow" can an oscilloscope be? Is it governed
by
> Nyquist criteria here? Thanks
> Al-U

Except if you are a mother board designer you will very probably not need to
look at these high frequency signals... And I guess that even motherboard
designers don't... Firstly because all external buses are far slower (400MHz
max ?), then because probing such signals is a nightmare (just calculate how
many pF you can afford to have a low impact on 1GHz digital signals that
have bandwidths up to 10GHz...), and lastly because you will very probably
not be able to do anything useful with the scope's outputs...

So my guess is that a standard (say 200-500MHz) scope is working for 99,99%
of the applications (all I/O applications). If you need really to look at
high speed buses then don't buy a scope but a quick logic analyzer, and
especially buy VERY GOOD probes. By the way look at the recent announcements
from Tek or HP : they are all working at least as much on the probes than on
the analyzers...

Friendly,
Robert