Keithley 7021 Instruction Manual page 58

Measure
I
C
POWER
Source
V
CE
Voltage Source
Output
Source
I
B
Current Source
Figure 5-8
Configuration for current gain and common-emitter test
In order to perform the current gain test, the voltage source
is first set to the desired value of V
then set to a base current value that will result in the desired
value of I as measured by the DMM. The current gain can
C
then be calculated as outlined in the previous paragraph.
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HI
Amps
LO
Model 2000
Output
DMM
Common
LO
Model 230
Model 224
A. Test Configuration
DUT
I
B
224
Current
Source
B. Simplified Equivalent Circuit
. The current source is
CE
7021
1
12
HI
1
12
Dual 1x12 MUX
Note: Bank B channels 13 through
18 are not used.
I
C
V V
CE
+
-
In order to reduce errors caused by voltage burden, use a
higher current range on the Model 2000 DMM. Doing so
will result in the loss of one or two decades of resolution,
but 3 1/2 or 4 1/2-digit resolution will probably be adequate
for most situations.
Operation
C
B
E
1
12
C
B
E
DUT (12)
2000
DMM
230 Voltage
Source
5-11