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DDR2 Debugging with both differential and single-end probe

Question asked by KUDJUNG on Jun 12, 2009
Latest reply on Jun 15, 2009 by marowley

I have some question(need some suggestion). I've a DSO8000 system, couple of 1130A active probe(with some of differential browser) and couple of 10073C 10:1 probe.

I was trying to use the equipment to probe for some problem on the DDR2 bus with the DDR2 clock running at 189 MHz.

There's something that I notice and don't understand.
Here is my probing method.
-Active probe with differential browsing attach to DDR CK+/-

-Whenever I tried to use the 10073C probe other signal on the bus with reference to the clock, it seem that the measured signal is delay by one clock. But if I use another 1130A measure the other singal then it seem to give a proper timing.
-I verified by put both 1130A and 10073C on the same signal and I did see that that singal see on 10073C is actually delayed by one clock from 1130A by one clock.

Is this because of different delay on the probe or something else? I believe I might miss something very basic.