Custom Sweeps - Keithley 6220 Reference Manual

4-6 Sweeps
The programmable parameters for a log sweep include the start and stop current
levels, the number of measurement points for the sweep, and the sweep delay.
The specified start, stop, and point parameters determine the logarithmic step
size for the sweep. Step size for the sweep in
Thus, the five log steps for this sweep are 0, 0.25, 0.50, 0.75, and 1.00mA. The
actual current source levels at these points are listed in
is the anti-log of the log step).
Table 4-1
Logarithmic sweep points
Measure
point
Point 1
Point 2
Point 3
Point 4
Point 5
When this sweep is triggered to start, the output will go from the bias level to the
start current source level (1mA) and sweep through the symmetrical log points
and then remain at the last point when the sweep is done. The time duration at
each step is determined by the sweep delay.

Custom sweeps

This sweep type lets you configure a customized sweep. Programmable parame-
ters include the number of measurement points (steps) in the sweep, the current
source level at each point, the delay period at each step, and the compliance set-
ting at each step.
When this sweep is started, the current output goes from the bias level to the first
point in the sweep. The sweep will continue through the current source steps in
the order they were programmed and stop after the last step. The time duration at
each step is determined by the delay setting for each point, which can be set to a
different value for each point.
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log10(stop) log10(start)
Log Step Size
= ----------------------------------------------------------------- -
log10(10) log10(1)
= ---------------------------------------------------- -
(
1 0
–
= ---------------- -
4
0.25
=
Source level
Log step (mA)
0 1
0.25 1.7783
0.50 3.1623
0.75 5.6234
1.0 10
Return to Section 4 topics
Model 6220/6221 Reference Manual
Figure 4-3 is calculated as follows:
–
Points 1 –
–
5 1 –
)
Table 4-1 (the current level