Input specification NI PXIe-5114 125 MHz Oscilloscope

[Rene7141]

Situation is as follows: we have is that we have several test-equipment where the PXIe-5114 is applied. This test-equipment is connected to a test-fixture on which our products are tested.

We want to be sure that all test-fixtures are identical and interchangeable between our test-equipment (using all the PXIe-5114).

So to be 100% sure that we measure in all situations the same value, we have to adjust our test-fixtures, assuming that all PXIe-5114 are 100% identical.

On page 3 at the PXIe-5114 Specifications we found:

Impedance and Coupling
    Input impedance
       50 Ω         50 Ω ± 1.5%
       1 MΩ        1 MΩ ± 1% in parallel with a nominal capacitance of 26 pF

Question: What is the tolerance for the stated 26 pF?

Thanks for your help!

[santo_13]

Typical practice in manufacturing is to perform Gauge Repeatability and Reproducibility to ensure the variation in the process (test system) does not influence the material (device under test). You could perform such GR&R activity to understand the test system variation (instruments, cables, fixtures etc.,) and determine your accuracy and thereby adjust your test limits instead of trying to get everything perfect.

[Rene7141]

Thanks, sure this will help us and we also figured out the requested tolerance of the Capacitor.
For now we have sufficient information.