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The instrument output is then turned off and the function
Print _ Data() is run to print the data to the TSB window . To
graph the results, simply copy and paste the data into a spread-
sheet such as Microsoft Excel and chart .
2.5.6 Using Log Sweeps
With some devices, it may be desirable to use a log sweep because
of the wide range of currents necessary to perform the test .
gram 3B
performs a log sweep of the diode current .
If your computer is currently connected to the Internet, you can
click on this link to begin downloading 'Diode_Fwd_Char_Log.
tsp': http://www.keithley.com/data?asset=50923.
Note that the start and stop currents are programmed just as
before, although with a much wider range than would be practical
with a linear sweep . With log sweep, however, the points param-
eter, which defines the number of points per decade, replaces the
steps parameter that is used with the linear sweep .
To run the Log sweep, we must send the code to the instrument .
One method is simply to right-click in the open script window
of TSB, and select 'Run as TSP file' . This will compile the code
and place it in the volatile run-time memory of the instrument .
To store the program in non-volatile memory, see the "TSP Pro-
gramming Fundamentals" section of the Series 2600 Reference
Manual .
Once the code has been placed in the instrument run-time
memory, we can run it at any time simply by calling the function
'Diode_Fwd_Char_Log()' . This can be done by typing the text
Pro-
'Diode _ Fwd _ Char _ Log()' after the active prompt in the
Instrument Console line of TSB .
2.5.7 Using Pulsed Sweeps
In some cases, it may be desirable to use a pulsed sweep to avoid
device self-heating that could affect the test results .
performs a staircase pulse sweep . In this program, there are two
additional variables ton and toff, where ton is the source on dura-
tion and toff is the source off time for the pulse . During the toff
portions of the sweep, the source value is returned to the ilevel
bias value .
If your computer is currently connected to the Internet, you can
click on this link to begin downloading 'Diode_Fwd_Char_Pulse.
tsp': http://www.keithley.com/data?asset=50922.
SeCTIon 2
Two-terminal Device Tests
Program 3C
2-7
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