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SeCTIon 3
Bipolar Transistor Tests
Series 2600
SourceMeter
Figure 3-3. Gummel plot test configuration
measures I
. SMUA sets V
B
CE
measures I
.
C
Due to the low current measurements associated with this type of
testing, the Keithley Model 2636 System SourceMeter instrument
is recommended . Its low level current measurement capabilities
and dual-channel configuration are ideal for producing high
quality Gummel plots of transistors .
3.4.2 Measurement Considerations
As written, the range of V
BE
increments . It may be necessary, however, to change these limits
for best results with your particular device . Low currents will be
measured so take the usual low current precautions .
3.4.3 example Program 5: Gummel Plot
Program 5 demonstrates the basic programming techniques
for generating a Gummel plot . Follow these steps to run this
program:
1 .
With the power off, connect a dual-channel System Source-
Meter instrument to the computer's IEEE-488 interface .
2 .
Connect the test fixture to both units using appropriate
cables .
3 .
Turn on the instrument and allow the unit to warm up for two
hours for rated accuracy .
4 .
Turn on the computer and start Test Script Builder (TSB) . Once
the program has started, open a session by connecting to the
instrument . For details on how to use TSB, see the Series 2600
Reference Manual .
3-4
Transistor
Under Test
I
B
Output HI
System
I
Channel B
V
Sweep V
BE
Measure I
B
Output LO
to the desired fixed value, and it also
test values is from 0V to 0 . 7 V in 0 . 0 1V
Test
V
CE
Fixture
V
BE
5 .
You can simply copy and paste the code from Appendix A in
this guide into the TSB script editing window
manually enter the code from the appendix, or import the TSP
file 'Gummel . t sp' after downloading it to your PC .
If your computer is currently connected to the Internet, you
can click on this link to begin downloading:
keithley.com/data?asset=50918
6 .
Install an NPN transistor such as a 2N5089 in the appropriate
transistor socket of the test fixture .
7 .
Now, we must send the code to the instrument . The simplest
method is 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
Programming Fundamentals" section of the Series 2600 Refer-
ence Manual .
8 .
Once the code has been placed in the instrument run-time
memory, we can run it at any time simply by calling the
function 'Gummel()' . This can be done by typing the text
'Gummel()' after the active prompt in the Instrument Con-
sole line of TSB .
9 .
In the program 'Gummel . t sp', the function
(vbestart, vbestop, vbesteps, vcebias) is
created .
•
vbestart
the base of the transistor
•
vbestop
•
vbesteps
voltage sweep
I
C
Output HI
Series 2600
System
I
SourceMeter
Channel A
Source V
,
V
CE
Measure I
C
Output LO
represents the sweep start voltage value on
represents the sweep stop value
is the number of steps in the base
(Program
5),
http://www.
Gummel
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