Reference
80E00 ElectricalSampling Modules User Manual 37
When making differentialor common-mode TDR measurements, the two steps
must arrive at the sametime at the reference plane (usually the connection point
to the device under test). Toadjust the TDR step deskew perform the following
steps:
Overview Adjusting TDR stepdeskew Controlelem ents& resources
Prerequisites 1. Eitherdi sconnect the transmission cables from the
device undert est (DUT)at the point where the cables
connect to the device, or short both lines to ground at
the DUT.Shorted lines are shown in this procedure.
2. Set channel deskew to zero.
Device
undertest
AdjustTDR step
deskew
3. Then, from the TDR setup window, adjust the TDR
Manual Step Deskew so that the propagation delay (T0)
between the incident edges is equal to the propagation
delay between the reflected edges, as shown in the
figure.
If using a math function, do not adjust the step more;
instead, adjust channel deskew as shown in the
following step.
--T 0
Steparrival at DUT
+T0
Adjustchannel
deskew
Forsome measurements, math summingand comparisons,
youm ay want to visually line up the reflection edges of both
TDRst eps, even though you have delayed the step assertion
time for one channel in the preceding step.
4. Todo this, first deskew the steps as shown above.
Then, from the Vertical setup window,deskew t he
channels. 0V
0V
Alignusing
channeldeskew
Adjusting TDR StepDeskew