Transistor Testing - Keithley 7021 Instruction Manual

Operation
Figure 5-7
Low resistance testing

Transistor testing

Typical transistor tests that can be performed with the aid of
the Model 7021 include current gain tests, leakage tests, as
well as tests to determine the common-emitter characteris-
tics of the device. The following paragraphs discuss these
tests and give typical equipment configurations for the tests.
Current gain tests
The DC or static common-emitter current gain of a transis-
tor can be determined by biasing the transistor for a specific
value of base current, I , and then measuring the collector
B
. The DC common-emitter current gain, β, of the
current, I
C
transistor is then determined as follows:
β
=
5-10
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182 Input
Model 182
220 Output
220 Current Source
182
Nanovoltmeter
V
220 Current
Source
I
C
---- -
I
B
7021
HI
1
12
LO
DUTs
HI
1
LO
12
Dual 1x12 MUX
R
7021 DUT
Figure 5-8 shows the test configuration and equivalent cir-
cuit for the current gain test. The Model 224 Current Source
is used to source the base current, I
age Source supplies the collector-emitter voltage, V
the collector current, I , is measured by the Model 2000
C
DMM. Switching among the transistors being tested is per-
formed by the Model 7021.
1
12
(12)
. The Model 230 Volt-
B
, and
CE