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Figure 3-2. Program 4 results: Common-emitter characteristics
3.3.4 Typical Program 4 Results
Figure 3-2 shows typical results generated by Example Program 4 .
A 2N5089 NPN transistor was used to generate these test results .
3.3.5 Program 4 Description
For the following program description, refer to the program
listing below .
•
Source I
•
IV compliance, 1 . 1 V range
•
Local sense
•
current: 10M
istart
•
current: 50µA
istop
•
: 5
isteps
Following SMUB setup, SMUA, which sweeps VCE and measures
IC, is programmed as follows:
•
Source V
•
Local sensing
•
100mA compliance, autorange measure
•
1 NPLC Line cycle integration (to reduce noise)
•
: 0V
vstart
•
: 10V
vstop
•
: 100
vsteps
Once the two units are configured, the SMUB sources istart,
SMUA sources vstart, and the voltage (V
Common-Emitter Characteristics (2N5089)
5.00E–02
4.00E–02
3.00E–02
2.00E–02
1.00E–02
0.00E+00
0
1
2
3
) and current (I
CE
4
5
6
7
8
V
(Volts)
BE
for SMUA are measured . The source value for SMUA is then
incremented by l _ vstep, and the sweep is continued until
the source value reaches vstop . Then, SMUB is incremented by
l _ istep and SMUA begins another sweep from vstart to
vstop in vsteps . This nested sweeping process continues until
SMUB reaches istop .
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 .
3.4 Gummel Plot
A Gummel plot is often used to determine current gain variations
of a transistor . Data for a Gummel plot is obtained by sweeping
the base-emitter voltage (V
specific increments . At each V
and collector current (I
Once the data are taken, the data for I
the screen . If using TSB, a plot can be generated using the "copy-
and-paste" method in a spreadsheet program such as Microsoft
Excel . Because of the large differences in magnitude between I
and I
, the Y axis is usually plotted logarithmically .
C
3.4.1 Test Configuration
Figure 3-3 shows the test configuration for Gummel plot tests .
)
SMUB is used to sweep V
CE
Bipolar Transistor Tests
I
= 50µA
B
I
= 40µA
B
I
= 30µA
B
I
= 20µA
B
I
= 10µA
B
9
10
) across the desired range of values at
BE
value, both the base current (I
BE
) are measured .
C
, I
, and V
B
C
across the desired range, and it also
BE
SeCTIon 3
)
B
is returned to
BE
B
3-3
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