04 | Keysight | Low Current Semiconductor Measurements
Using the B2980A Series Ammeter - Technical Overview
2. Floating ammeter design provides stable measurements for both
loating and grounded DUTs
(continued)
Grounded DUT coniguration
Figure 2 shows the case where one of the ends of the DUT is grounded. In this case the con-
nection scheme shown in Figure 1 cannot be used. The reason for this is that the ammeter
side of the DUT must always be loating and there is no way to apply a voltage to the DUT
except through the ammeter. Figure 2 shows the proper ammeter coniguration for a ground
-
ed DUT measurement. In this coniguration the ammeter common is loating and the voltage
source (Vs) is connected to the ammeter common. The source voltage (Vs) is applied through
the ammeter’s input terminal.
Note: In both the loating and the grounded cases, the outside conductor of the ammeter’s triaxial input
terminal is connected to the instrument’s chassis ground to maintain safe operating conditions.
Note: The B2985A and B2987A have a built-in voltage source that provides the following beneits:
–
The ability to synchronize the voltage source output with the measurement timing.
–
The ability to display the voltage and current relationship in an X-Y graph on the instrument front panel.
3. Measurement speed, iltering/averaging and zero cancelation
functions improve measurement data quality
Measurement Speed selection:
The B2980A series supports four measurement speeds: Quick, Normal, Stable, and Manual.
The Quick, Normal and Stable measurement speeds are available when using auto mode, and
they correspond to integrating over some fraction or multiple of the power line cycle (PLC).
For these cases the measurement speed is automatically set for a given measurement range
to provide the best data for the selected speed. If you want to control this parameter, then the
Manual speed setting is user deinable from 0.001 PLC to 100 PLC.
Filtering capability:
In addition to the measurement speed selection, you can also perform iltering on the mea
-
surement data. The iltering function can provide median averaging and a moving average to
reduce noise effects.
A
A
-
+
+
DUT
Vs
Shield (GND)
Guard
Ammeter is connected on the voltage source.
i
Ammeter (high)
Ammeter
Common
(Floating)
DUT is grounded
Figure 2. Coniguration to measure a grounded DUT.
