RE: [SI-LIST] : What speed scope should I consider?

Dima Smolyansky (dima@tdasystems.com)
Thu, 20 May 1999 12:33:56 -0700

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Chris:

Have you considered the rise time of your signals? That is another =
factor to look at, and quite often is the decisive one. If you know your =
rise time, you can determine 3dB bandwidth as 0.35/tr; then the scope =
bandwidth should be about 3X that in order to get practically no =
distortion form the scope.=20

Alternatively, you can look at 5X your device clock speed, and if this =
number is higher than the one you got from the rise time, use it. Seems =
like this requirement is satisfied quite well in your case - your 1.5 =
Ghz scope will do fine for 66Mhz board speed.

In any event, remember that beside the scope you also need your cables =
and device interfaces with such performance that will allow you to =
maintain the desired bandwidth.

Thanks,

-Dima
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D
Dima Smolyansky
TDA Systems, Inc.
7465 SW Elmwood St.
Portland, OR 97223
(503) 977-3629
(503) 245-5684 (fax)
dima@tdasystems.com
http://www.tdasystems.com
=20
The Interconnect Modeling Company(TM)

-----Original Message-----
From: Chris Bobek [SMTP:cbobek@cadence.com]
Sent: Thursday, May 20, 1999 11:33 AM
To: si-list@silab.eng.sun.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 I
would like other opinions...

Thanks,

Chris

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