Setting Transistor Parameters in PSPICE
EECE 235
1. Create a new library text file (yourname.lib) which consists of the model fo the
Q2N2222 transistor. You may do this by opening c:\msim*\lib\eval.lib or
d:\msim*\lib\bipolar.lib in notepad or Wordpad (or equivalent) and copying and
pasting the .model statement (or you can just type the following .model statement into
your file).
.model Q2N2222A NPN(Is=14.34f Xti=3 Eg=1.11 Vaf=74.03 Bf=255.9 Ne=1.307
+
Ise=14.34f Ikf=.2847 Xtb=1.5 Br=6.092 Nc=2 Isc=0 Ikr=0 Rc=1
+
Cjc=7.306p Mjc=.3416 Vjc=.75 Fc=.5 Cje=22.01p Mje=.377 Vje=.75
+
Tr=46.91n Tf=411.1p Itf=.6 Vtf=1.7 Xtf=3 Rb=10)
*
National
pid=19
case=TO18
*
88-09-07 bam creation
2. Copy this model 3 times within your library file.
3. Rename the models Q1, Q2 and Q3 (in place of Q2N2222A). At this point, you may
set the parameters to match your measured results for the 3 transistors. Parameter Bf
corresponds to the DC beta, Vje corresponds to the Vbe(on) voltage of your transistor
and Is corresponds to the Is of your transistor. Get this from the relationship of
Ic=α(Is)(exp(Vbe/Vt)) with α determined from your AC beta
4. When drawing your schematic, do not use part Q2N2222A from the library. Instead,
use QbreakN from the breakout.lib library.
5. In order to access your models, you must highlight the transistor and go to Edit and
Model. Once here, click on “Edit Instance Model (Text)” and copy one of the .model
statements from your library file into the text box. This will automatically save your
models into a library file with the same name as your schematic file. Do this for each
of your transistor models.
6. After simulation, you can verify that the parameters for the transistor models match
the parameters from your actual transistors by looking at the output file.