Reference
80E00 ElectricalSampling Modules User Manual 43
TDR Impedance Measuring
This stand-alone applicationimplements the TDR calibration procedure(s)
specifiedby the IPC --TM--650test methodology. It enhances the accuracy and
repeatabilityof impedance measurements by calibrating the test setup to correct
for losses andimpedance discontinuities. Additionally, this application can use a
databasefor storing TDR measurements. This application is not installed on your
instrument, but it can beinstalled from the 8000 Series Demo Application CD
shipped with the instrument.
For more information seeT DR Impedance-MeasuringApplication Online Help.
Detecting BlownInputs
Because of their technology, high-bandwidth sampling modules are vulnerable to
damage through staticdischarge and overvoltages (EOS) to the input.
Damage canoccur instantaneously. Under most conditions when EOS damage
occurs, the tracewill be flat. It typically involves short-period, high-current
discharge.The damages can be blown diodes, as indicated by large offset, or no
response to input.
Tocheck for damage, use one of the following procedures:
HIf checkingan 80E04 sampling module and your instrument has TDR
capability,attach a 50 Ωtermination to the channel input and perform a TDR
measurementof the attached fitting. Adjust the HORIZONTAL SCALE to
500 ns per division. This should display the entireTDR step from edge to
edge. Display the steptop at 40 mρper division and check for flatness. If the
top is bowed, sagged,hooked, or tilted, assume static has damaged the
module and serviceis required. See Figure 16 on page 44.
HIf checkinga non-TDR sampling module, use a proceduresimilar to the
preceding procedure, but use an external step source.

Checking For Damage