Agilent Technologies B1500A Training Manual page 57

Why Kelvin Measurements?
I
B
In the example above, the device is connected with a SMU on the base sweeping current, a voltmeter
on the collector, and the emitter is grounded with a Kelvin SMU. The base SMU does not have to be
Kelvin since we are only forcing current and do not care about measuring the cable loss in the base.
Also, the collector SMU is being used only as a high impedance voltmeter, so there is no cable loss
in this lead.
The emitter on the other hand, must be connected to a Kelvin SMU. Because of this, we can
compensate for the 0.214 ohm path through the cable and fixture. From the graph we can see the
emitter resistance is 0.735 ohm when compensated using the Kelvin connection. Non-Kelvin
resistance is 0.949 ohm, due to the extra 0.214 ohm cable and fixture resistance error.
V
monitor
C
20
Ω
Re = 735 m
Slope = 1/Re
(Kelvin)
Ω
Rcable = 214 m
Ib (mA)
0.1
0
5-37
Slope = 1/(Re+Rcable)
(Non-Kelvin)
Vc (mV) 50
Module 5
Basic Measurement