Agilent Technologies B1500A Training Manual page 78

Debugging A Noisy Probe System
Where to Start?
Sweep 0 to 1 volt with no cables attached to SMU
Check that there is a +/- 3 fA base line
Add prober cables but no prober
Wait several minutes
Still +/- 3 fA base line?
Add shielded prober but no probes
Add probes
This is a systematic strategy for focusing in on the sources of noise and error. You can be very
surprised. Some prober cable is not low loss. You may see popping noise due to relaxing of Teflon
fiber in the cables, high current level due to poor dielectric loss, etc. You may find improper triax
adapters, high levels of stray capacitance, etc., as you add prober and probe connections.
6-6
Module 6
Low Current Measurement