Comment by jacquesm

Ah, but that may well be because of your scope probe's leads! The sharper the edge the more likely that will happen. That's what those shitty little springs are for that come with your scope probe: you disconnect the ground wire and put that spring on the naked scope probe pin around the ground collar. Then where you want to measure you use the pin to go to the signal and the little spring to reach the nearest ground. Presto: clean signal (or at least, much cleaner). Also, make sure to tune your probe (that's what the little plastic screwdriver with metal tip is for, there is a small trimmer in the probe you can reach through a hole and that is critical at high frequencies) and avoid probes with switchable 1/10 like the plague, over time the switches go lame and then you'll be tracking all kinds of weird gremlins.