Craig Sawyers <c.sawyers@...>
I'm thnking now, would it be more accurate and easier to simulate aThe thing to do is use a probe adaptor. Tek used to supply these with some
of their probes. Looks like a little BNC, but the receptacle takes the
probe tip. You solder the centre pin to the signal, and the outer to the
ground plane (you've got one of those - right?). When you plug the scope
probe in, there are virtually no additional errors arising from tip grabber
and ground clip inductance, and you get a very clean signal.
You can do the same thing with a FET probe too, and reduce the loading to
one or two pF.
If the circuit has to look into 50 ohms, load the circuit locally with a
50-ohm resistor (a surface mount component connected between the IC pin and
ground plane is ideal), then probe the circuit as above.