Common-Emitter Characteristics Tests - Keithley 7074 Instruction Manual

SECTION 3
Applications
3.3.2
Common-Emitter Characteristic
Tests
Common-emitter characteristics are determined by set-
ting the base current, Ie, to specific values. At each IB
value, the collector-emitter voltage, VCE, is swept across
the desired range at specific intervals, and the collector
current, Ic, is then measured. When the data are plotted,
the result is the familiar family of common-emitter
curves (Figure 3-5).
0
1
2 3 4 5
VCE , volts
'igure 3-5. Typical Common-Emitter Chnracteristics
The same test configuration that is used for current gain
tests can be used for measuring common-emitter charac-
teristics (Figure3-4). The Model 7.24 is used to set thebase
current, I&, to the desired values. The Model 230 Voltage
Source provides the collector-emitter voltage, VCE, and
the Model 196 DMM measures the collector current, 4.
3.3.3
Example Transistor Test Program
IEEE488 interface). The program will allow the operator
to type in the desired voltage source (VCE) and current
source (IIJ) values.
Note that the program assumes that the Model 7074 is lo-
cated in slot 1 of the mainframe, and that 48 transistors
are to be tested for current gain. Because of the switching
configuration used, two bank-input combinations must
be closed simultaneously. For example, Row A, Input 1,
and Row E, Input 1 will be closed at the same time.
PROGRAM
COMMENTS
10 REMOTE 716
Put 707 in remote.
20 REMOTE 7t3
Put 230 in remote.
30 REMOTE 719 Put 224 in remote.
40 REMOTE 707
Put 196 in remote.
50
CLEAR7
.__
140 OUTPUT 719 ;'l':lb;"X
150
60 OUTPUT 716
IF AES(Vce)> 30 THEN PRINT
"WARNING: HAZARDOUS "OLT-
;'AOX
AGE WILL SE APPLIED TO DE-
70
VICE DURING TEST
160 INPUT'PRESS ENTERTO BE-
OUTPUT713
GIN".A$
;'lZX
170 OUTPUT719 ;'FlX
160 OUTPUT713 ;'FiX
60
190 FOR I-65T0 66
OUTPUT719
200
;'"tOX
Ci$=CHR$(I)
210
90
CZ$=CHR$(l+4)
OUTPUT 707
220
:'F3ROGlT3X
FOR J.1 TO 12
230
100 INPUT 'VCE VALUE (0.IOivi', Vce
OUTPUT 716 ;"c';Ci$;J;'X
240
110
OUTPUT 716 ;"C';CZ$;J;'X
250
IF ABS(Vce) ,101 THEN GOT0
WAIT,
260
120
TRIGGER 707
OUTPUT 713
270
;'v":Vce;X
ENTER 707 ;b
260
120
PRINT 'BANK ":Cl$;' CHANNEL':
INPUT "I8 VALUE (0-iOiMA)",lb
J;"DEVICE CURRENT GAIN:"; lc,,b
290
130
OUTPUT 716 :N":Cl$:J;'X
IF ABS(lb) ,iOiE-3 THEN GOT0
300 OUTPUT 713 ;'N';CZ$;J;'X
l!m
310
NEMJ
320
NEXT,
330 OUTPUT 713 ;'FOX
340 OUTPUT 719 <FOX
350
END
Program 2*4 c"Re"t.
Display hazard warning.
Clear instruments.
Reset 707.
230 20mA wren1 limit.
224
10" compliance limit.
196 DCA,autoraoge,oneshol
trigger.
Input "CE value.
Check voltage limits.
Program 230 voltage.
Input IBYabe.
Check current limits.
Pause lor slail signal from opera-
10,.
Turn on 224 output.
Turn on 230 ou10u1.
Loop for ASCII A-0 values.
Define row A-D command letter.
Define row F-H command letter.
Loop ior all 12 inputs in bank.
Close row A-D, input J.
Close row E-H. input J.
Wail one second tar settling.
Trigger 196 reading.
Gel 196 current reading (Ic).
Display row A-D, input J reading.
Open row A-D. input J.
Open row E-H, input J.
Loop back for next input.
Loop back 101 next row.
Turn oli 230 output.
Turn oil 224 output.
The example program below shows general techniques
for performing current gain tests using the test setup
shown in Figure 3-4 (note that the Model 224 Current
Source must be equipped with the optional Model 2243
3-6