Keysight B1500A Configuration and Connection Guide, Edition 6
3-15
Connection Guide for Wafer Prober
Connection for low resistance measurement
Figure 3-15
Kelvin connection
•
For the non-Kelvin connection, the voltmeter measures the voltage drop of resistance
r
F1
,
R
DUT
, and
r
F2
.
•
For the Kelvin connection, the voltmeter measures the voltage drop of resistance
R
DUT
only. The impedance of the voltmeter is very high, so the voltage drop of resistances
r
S1
and
r
S2
can be ignored.
The Kelvin connection is effective even when forcing voltage. The voltage drop due to the
residual resistance of the Force line wiring is fed back to the voltage source via a
comparator in the Sense line. The input impedance of comparator is high, and current flow
into the Sense line is very low. So output error is not significant if the Sense line wiring has
a residual resistance of 10
or less. Therefore, the specified voltage appears at the sense
point (point where Sense line contacts Force line).
NOTE
Kelvin connection and non-Kelvin connection
To make the Kelvin connection, use both Force and Sense terminals. Connecting the Force
and Sense lines together at the terminal of the DUT (device under test) minimizes the
measurement error caused by the residual resistance of the connection cables. The Kelvin
connection is effective for the low resistance measurement and the high current
measurement.
If you want to simplify the cable connections, use the 2-wire connections by connecting the
Force terminals only. Then open the Sense terminals. This is the non-Kelvin connection.
The Force terminals can be used to force and measure dc voltage or current via
R
s
in Figure
Figure 3-16
Simplified SMU circuit diagram
(a) non-Kelvin connection
(b) Kelvin connection
r
F1
r
F2
R
DUT
r
S2
r
S1
V
V
V
r
F1
r
F2
R
DUT
Buffer
Guard
Force
Sense
x1
Rs
V
Shield
