Max 'useable' bandwidth on Agilent x2024a?

[StubbornGreek]

Can anyone who has a x2024a or x2022a comment on when the signal actually starts to become misrepresented by the scope? I know the rated b/w is 200MHz; just trying to get an idea how far you can actually push these.

Also, if someone has the means and is willing to contribute a small bit of their time, I'm curious to know how bad a 370MHz signal looks on one of these. Thank you.

[StubbornGreek]

Bumpers...

[alm]

Bumping your topic because you didn't get an answer within a day is not going to make you very popular.

I don't have access to one of those scopes. The bandwidth represents the -3 dB point, so a 1 Vpp 200 MHz sine will be displayed as a 0.7 Vpp 200 MHz sine. Rule of thumb for analog signals used to be that the scope should have a bandwidth about 5x higher than the frequency of the signal. This was for a qualitative assessment on a CRT only.

For digital signals it's better to look at the rise times. For accurate rise times measurement, the system rise time of the scope and probe should be lower than the rise time of the signal. How much lower depends on the required accuracy. Here are some appnotes on this topic.

A 370 MHz signal will most likely look like a severely attenuated sine wave, regardless of the original signal. How much attenuation depends on the frequency response of the front-end. Aliasing might also start to become a problem. Keep in mind that a square wave is composed of a large number of odd harmonics, these harmonics will be even more attenuated than the fundamental.

[EEVblog]

IIRC my 500MHz 3000X series had a -3dB point of >600MHz, and I was able to display a 1GHz sine wave at very low amplitude of course.

Dave.

[alm]

Another issue might be trigger bandwidth. It will not necessarily trigger at signals far beyond the rated bandwidth. The trigger will be less sensitive at higher frequencies.

[StubbornGreek]

Thank you very much for your input. Sorry to bump so early but I was trying to take advantage of a time-sensitive buying opportunity (which didn't come to fruition).

alm: Thank you for the links (good reading) and quick summation - your time is appreciated. Also, triggering is part of the reason I asked for a 370MHz example.

Dave: I remember that episode, as a matter of fact, that episode is what made me wonder of the x2xxx series ability past its rated bandwidth.

Regardless, I think missing the deal is almost a good thing. I really wanted more bandwidth and pushing a scope that far is just foolish.