Keithley 2600a series, Reference Manual, Page: 87 / 696

2600AS-901-01 Rev. B / September 2008 Return to Section Topics 3-15
Series 2600A System SourceMeter® Instruments Reference Manual Section 3: Basic Operation
Figure 3-3
2-wire resistance sensing
Figure 3-4
4-wire resistance sensing
Sense selection
Front panel sense selection
To select sensing mode:
SourceMeter
HI
LO
I
V
M
Input, Output
V
M
V
R
Test Current (I)
Resistance
Under Test
Lead
Resistances
R
S
R
LEAD
R
LEAD
= Current sourced by SourceMeter
= Voltage measured by SourceMeter
= Voltage across resistor
I
V
M
V
R
Measured resistance = = + (2 X )
Actual resistance = =
V
M
I
R
S
R
LEAD
I
V
R
R
S
SourceMeter
4-wire Sense HI
4-wire Sense LO
I
Input/Output HI
V
M
V
R
Test Current (I)
Resistance
Under Test
Lead
Resistances
R
S
R
LEAD
R
LEAD
= Current sourced by SourceMeter
= Voltage measured by SourceMeter
= Voltage across resistor
I
V
M
V
R
and measured resistance = =
V
M
I
V
M
Sense Current (pA)
Input/Output LO
R
LEAD
R
LEAD
Because sense current is negligible, = V
M
V
R
I
V
R
= R
S