Keithley 2520, User Manual, Page: 108 / 329

Model 2520 User’s Manual Sweep Operation 7-3
Logarithmic staircase sweep
This sweep is similar to the linear staircase sweep. The steps, however, are done on a loga-
rithmic scale as shown in the example sweep in
Figure 7-2 . This is a 5-point log sweep
from 1mA to 10mA. As with the staircase sweep, the measurement time is the same for all
steps. (Again, DC mode waveforms are shown.)
Figure 7-2
Logarithmic staircase sweep
The programmable parameters for a log sweep include the start and stop levels and the
number of measurement points for the sweep. The specified start, stop, and point parame-
ters determine the logarithmic step size for the sweep. Step size for the sweep in
Figure 7-2 is calculated as follows:
Stop
(10)
X
X
X
X
X
Log Points = 5
1
10
5.6234
3.1623
1.7783
mA
Log
Scale
PW +
Delay
PW +
Delay
PW +
Delay
PW +
Delay
PW +
Delay
Note: DC Mode Shown.
Start
Log Step Size
log10(stop) log10(start)
–
Points 1
–
------------------------------------------------------------- =
log10(10) log10(1)
–
5 1
–
-------------------------------------------------- =
1 0
–
( )
4
---------------- =
0.25
=