pcb layers on BGAs Spartan-3

"Sylvain Munaut" schrieb im Newsbeitrag news:42a9fdac$0$346$ snipped-for-privacy@news.skynet.be...

OK, so this proves the old suggestion. "Use your head before opening your mouth". ;-)

Regards Falk

Single ended? Cheers, Syms.

Yup.

John

Wow, I'm impressed! Single ended clock signal I guess, not random data? Cheers, Syms.

Here's one of our gadgets, built for the NIF laser...

All the fast stuff is EclipsLite logic, pecl mode, and most of it is single-ended except for a major clock which is a diff microstrip.

If you want low jitter, you have to know The Secret.

John

I guess you might need to know more than one Secret!! I see why you refer all your stuff to the power plane, makes sense with the single ended stuff in your logic family of choice. (ECL is referred to ground, so PECL is referred to the power plane.) I tend to use exclusively diff pairs, LVDS, PECL and CML, referred to ground. Works fine. I wonder if diff pairs work slightly better referred to VCC? Hmmm. I see the single digit jitter you mentioned is RMS, not pk-pk. That makes it a little easier. Not that I'm not still very impressed! Cheers, Syms. p.s. As for Secrets, do you know where Syd Barrett lives?

No, I refer my stuff to *any* plane that happens to be handy!

Doubt it. Planes is planes.

Well, you can't actually measure p-p jitter.

Pink Floyd? Now *that* is a noise source!

John