Keithley 3730

Series 3700
System Switch/Multimeter User's Manual Section 5:
Basic Digital Multimeter (DMM) Operation
Document Number: 3700S
-900-01 Rev. A / August 2007 5-
27
The two-wire constant-current method is shown below.
Figure 5-15: Two-wire constant-current source method
The four-wire constant-current method is shown below.
Figure 5-16: Four-wire constant-current source method
Ratiometric method
For the 10M and 100M ranges, the ratiometric method is used to measure resistance. Test
current for this method is generated by a 6.4V voltage source through a 10M reference
resistance (R
REF
), as shown.