2606B System SourceMeter® Instrument Reference Manual
Section 4: Theory of operation
2606B-901-01 Rev. B / May 2018
4-15
Contact check
When a contact check measurement is being performed, two small current sources are switched in
between the HI and SENSE HI terminals and the LO and SENSE LO terminals. By controlling the
switches illustrated in the following figure, the current from these sources flows through the test leads
and through the contact resistance, as shown. To accurately measure the resulting contact
resistance, the differential amplifier outputs are measured once with the current sources connected,
and again with the current sources disconnected. This allows for compensation of various offset
voltages that can occur.
Figure 94: Contact check circuit