Keithley 2001-TCSCAN - Page 55

Operation
3-26
■ 4-wire resistance tests
More precise measurements over a wider range of system
and DUT conditions can be obtained by using the 4-wire
measurement scheme shown in Figure 3-4. Here, separate
sense leads from the DMM are routed through the scanner to
the resistor under test. The extra set of sense leads minimizes
the effects of voltage drops across the test leads, greatly
reducing measurement errors with lower DUT resistances.
Note, however, that an extra two poles of switching are
required for each resistor tested. For this reason, only four
resistors can be tested using this configuration.
2
DUTs
(4)
R
A. Test Configuration
B. Simplified Equivalent Circuit
5
7
10
1
4
HI
LO
Sense
HI
Sense
LO
HI
Sense HI
LO
Sense LO
2001-TCSCAN
DUT
2001-TCSCAN
Ω
Out A
Out B
DMM
Input HI
Input LO
Sense HI
Sense LO
DMM
Figure 3-4
4-wire resistance test connections