How do I measure signals in the GHz range?

Hello,

I've got a storage oscilloscope here with a bandwith of 6 GHz. Unfortunately only the default probes with 500 MHz bandwidth are included.

Now I would like to measure signals in the range of 2.5 gigabit per second. Thus, I am looking for suitable probes with sufficient high bandwidth. But I think bandwidth is not all there is to consider. There is also the question whether to use active or passive probes and probably impedance and capacitance will also play a mayor role.

In addition, the signals I would like to measure on the board are routed differentially (selfevident at the frequencies!), so that differential probe would surely be the suitable choice here. But wouldn't it be possible to measure asymmetrically to ground potential, anyway?

Guys, how do I find the right solution for my task? Unfortunately I'm an absolute newbie in measurement technique so pardon me for bothering you. I already hit some books but I couldn't find out, anyhow.

Thanks for support. Saul

Reply to
Saul Bernstein
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Talk to whoever made your scope - (Tek, Agilent or LeCroy ?). The probes are going to cost you well over £1000 each so you might be able to arrange a demo and get some free instruction that way. The big 3 manufacturers all have web sites with a reasonable amount of information about measuring technique.

Michael Kellett

Reply to
MK

Hello,

you should take a look at

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regards, A.S.

Reply to
sca

Though I never tried GHz range stuff, I did use the resistive probe as described:

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And cheap too :-)

--
 - Blarp the Enigmatic
Reply to
René

What kind of scope is it?

John

Reply to
John Larkin

What's so "self-evident" about it? Your sat TV receiver works at 12GHz and is 100% unbalanced.

You don't say what the measurements are supposed to be for. When working with data at these rates, the correct tool these days is a BERT, or J-BERT, not a scope.

Unless your "scope" is a BERT with a missing personality module...

Reply to
a7yvm109gf5d1

The initial test on multi-GB systems I know of, is done by looking at the recovered signal with a scope. BERT is only good on a path that was once known "good" but is now showing system errors. IMO a BERT test set is something you use to prove there really is (or isn't) something wrong, just before you grab your scope.

Reply to
Don Bowey

Scopes do the basic electrical signal integrity measurements, levels and timing and jitter and eye diagrams. Packets and protocols are higher levels from there.

John

Reply to
John Larkin

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Heterodyne the 2.5GHz signals down to 200MHz or so ;)

Reply to
larwe

Pardon the French, but that's nonsense. Nothing in a sat receiver works at 12 GHz. That's self-evident if you take just a quick look at the antenna cable --- no way a 12 GHz signal can survive 10+ meters of that coax cable and connectors.

The only place 12 GHz take place in a sat TV setup is in the LNB (for those who don't know: that's the gadget at the end of that arm, near the center of the dish). From there onwards the signal is in the 1..2 Ghz range, at most.

Reply to
Hans-Bernhard Bröker

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Allthoug I dont work with HF ... I think there will be a problem with measuring a 2.5 G bit signal with a 6 Ghz scope unless the signal is a sine. ..if its a square signal ,the third harmonic have to be shown too ,to get a usable picture ,and that is allready 7.5 Ghz. So if you could get a picture of the signal, you would not know if it was true. alex

Reply to
Alex

6G's should be fine, if it can be probed properly. 2.5 GBPS is equivalent to a 1.25 GHz square wave, 400 ps per data element, and the rise time of a 6GHz scope will be around 60 ps.

John

Reply to
John Larkin

That all depends on what you are looking for. Time relationships, the relation of a pulse position relative to others, is valid.

Reply to
Don Bowey

F'up abuse detected.

[plonk]

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Reply to
Peter Hucker

Heard 599 here.

Reply to
Don Bowey

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oh yes ..your right John it is , only 1.25 G hz, and Also ,I agree , Don. Alex

Reply to
Alex

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