PrecisionProbe Correction
Two methods exist for correcting probe responses, Vout/Vin
and Vout/Vsource
Vout/Vin Correction
Vout/Vin characterizes the output of the probe as a function of the input at the
probe tips. Defining the response this way allows you to evaluate the probe’s
accuracy in reproducing the actual signal present in your system with the probe
attached. This correction is known as Vout/Vin, which is what you’d see with a
real band limited probe that has finite input impedance. PrecisionProbe corrects
the “Vout/Vin” response to be flat with frequency and phase to your defined
bandwidth limit. It does not correct the loading effects of the probe. It should be
noted that Keysight’s probe frequency response corrections are typically defined
using Vout/Vin.
Vout/Vsource Correction
The second way to correct probes is an estimate known as Vout/Vsource,
this method corrects the probe as “what would be there if the probe were not
present.” There are oscilloscope and probe manufacturers that design their probes
and DSP correction software to display what the waveform “would have been”
in the absence of the probe. One drawback of defining the probe’s response
in this manner is that if the probe’s loading causes your circuit to lose some
timing or amplitude margin, you probably want to know that when you make a
measurement. Vout/Vsource compensation will hide these effects from you.
PrecisionProbe also gives you the freedom to choose this method of correction,
which can be effective if probing at the transmitter.
Figure 6. A probe that has perfect transfer
function shows an exact copy of a signal at
the input. A probe that has a perfect system
response shows the signal at the input of
probe boosted by the estimate amount of
loading due to the probe.
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