Keithley 6220 Reference Manual page 177

Model 6220/6221 Reference Manual
Differential Conductance step size – When using the repeating filter with Differ-
ential Conductance, the actual step size run for the test is the programmed step
size divided by the filter count:
Step Size (repeating filter) = Programmed Step Size / Filter Count
For example, assume the programmed step size is 10µA and the Filter Count is
10. When the Differential Conductance test is run, the actual step size will be 1µA
(10µA / 10).
Model 2182/2182A measurement rate
The speed (rate) setting of the Model 2182/2182A is queried. If the NPLC speed
setting is not an integer value, it will be changed to 1 PLC (examples of non-inte-
ger values are 0.1, 1.3, and 17.5).
Voltage offset compensation
Disabling Front Autozero on the Model 2182/2182A results in high voltage offset
for voltage measurements. To compensate for this offset, the Model 622x per-
forms the following action:
•
Depending on the integration time for the Model 2182/2182A, it may take several
seconds for the Model 622x to acquire the V-zero value. With the Model 2182/
2182A set for 5 PLC, V-zero acquisition will take approximately three seconds.
Configuration checks
The Model 622x performs a number of checks on the configuration for Differential
Conductance and generates the following error and status messages:
If any of the following errors occur, Differential Conductance will still run, but it will
not perform the complete test that was configured:
•
•
If the following error occurs, Differential Conductance will still run, but corrupt data
will be acquired:
•
The occurrence of the following status message does not abort the test:
•
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The Model 622x acquires the voltage offset (V-zero) value from the
Model 2182/2182A and will factor it into the calculations for Differential
Conductance voltage. This technique effectively compensates for
Model 2182/2182A offset voltage. During V-zero acquisition, the message
"Acquiring V-Zero ..." will be briefly displayed.
Error -225 Out of Memory
Error +408 Conductance truncated
Error +411 Diff. Conductance step error
Status +412 Diff. Conductance upranged
Return to
Delta, Pulse Delta, and Differential Conductance 5-57
Section 5 topics