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SeCTIon 3
Bipolar Transistor Tests
may be necessary to increase the number of iterations if the target
range is reduced .
3.5.8 Configuration for Fast
Current Gain Tests
Figure 3-6 shows the test configuration for an alternate method
of current gain tests—one that is much faster than the search
method discussed previously . SMUB is used to supply V
it also measures I
. SMUA sources the emitter current (I
B
than the collector current (I
current instead of collector current, the current gain calculations
must be modified as follows:
I
– I
_____
E
B
ß =
I
B
When a System SourceMeter instrument is pro-
grammed for remote sensing, hazardous voltage
may be present on the SENSE and OUTPUT termi-
nals when the unit is in operation regardless of the
programmed voltage or current. To avoid a possible
shock hazard, always turn off all power before
connecting or disconnecting cables to the Source-
Measure Unit or the associated test fixture.
Because of the connection convention used, I
V
must be programmed for opposite polarity than
CE
normal . With an NPN transistor, for example, both V
and I
must be negative .
E
Series 2600
SourceMeter
Channel B
Source V
Measure I
Figure 3-6. Test configuration for fast current gain tests
3-8
) . Because we are sourcing emitter
C
WARNING
NOTE
Sense LO
Output LO
System
V
,
I
CE
B
Sense HI
Output HI
I
B
3.5.9 example Program 6B: DC Current
Use Program 6B in Appendix A to demonstrate the fast method of
measuring current gain of bipolar transistors . Proceed as follows:
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 .
, and
CE
Note that OUTPUT HI of SMUB is connected to the base of the
) rather
E
DUT, and SENSE HI of SMUB is connected to the emitter .
3 .
Turn on the System SourceMeter 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 .
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 'DC_Gain_Fast.tsp' 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=50926
6 .
Install an NPN transistor such as a 2N5089 in the appropriate
transistor socket of the test fixture .
and
7 .
Now, we must send the code to the instrument . The simplest
E
method is to right-click in the open script window of TSB,
and select 'Run as TSP file' . This will compile the code and
CE
place it in the volatile run-time memory of the instrument .
I
C
Test
V
CE
Fixture
I
E
Gain Using Fast Method
Output LO
Series 2600
System
SourceMeter
I
Channel A
Source I
Output HI
(Program
6B),
http://www.
E
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