Keithley 2657A

Model 2657A High Power System SourceMeter® Instrument Reference Manual Section 3: Functions and features
2657A-901-01 Rev. B/December 2012 3-25
In this example:
A = 0, V
start
= 100, V
end
= 1000, N = 5
Using the formula above, k = 1
Step size (b) for the sweep in the above figure is calculated as follows:
Figure 37: Logarithmic staircase sweeps (2)
Therefore, b = 10
(log step size)
= 1.7783
The five log steps for this sweep are listed in the Logarithmic sweep points table below.
Logarithmic sweep points
Source point (N) Source level (V) Step number (i)
1 100 0
2 177.83 1
3 316.23 2
4 562.34 3
5 1000 4
When this sweep starts, the output will go to the start level (100 V) and sweep through the
symmetrical log points.
To configure a logarithmic staircase sweep, use the smua.trigger.source.logY()function. This
function configures the source values the source-measure unit (SMU) will output when performing a
logarithmic sweep. After configuring the sweep, you must also enable the source action by setting the
following attribute:
smua.trigger.source.action
Example:
-- Configure a sweep from 100 to 1000 V in 10 steps with an asymptote of 0 V.
smua.trigger.source.logv(100, 1000, 11, 0)
-- Enable the source action.
smua.trigger.source.action = smua.ENABLE
For more information, see smuX.trigger.source.logY() (on page 7-244).