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Old 26th March 2004, 07:30 AM   #1
Bricolo is offline Bricolo  France
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Default 2N2222 Spice model?

I'm looking for an accurate model for this transistor.

The one I have with simetrix doesn't behave like the real one I used
With real life measurements, I got a -3dB at 600kHz, with the simulation it's at 160Mhz. Quite a difference!


Does anyone have another model that this one?

.model Q2N2222 npn ( IS=2.48E-13 VAF=73.9 BF=400 IKF=0.1962 NE=1.2069
+ ISE=3.696E-14 IKR=0.02 ISC=5.00E-09 NC=2 NR=1 BR=5 RC=0.3 CJC=7.00E-12
+ FC=0.5 MJC=0.5 VJC=0.5 CJE=1.80E-11 MJE=0.5 VJE=1 TF=4.00E-10
+ ITF=2 VTF=10 XTF=10 RE=0.4 TR=4.00E-08)


Thank you
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Old 26th March 2004, 08:17 AM   #2
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Default ZETEX Version

*ZETEX 2N2222A Spice model Last revision 9/12/92
*
.MODEL Q2N2222A/ZTX NPN IS =3.0611E-14 NF =1.00124 BF =220 IKF=0.52
+ VAF=104 ISE=7.5E-15 NE =1.41 NR =1.005 BR =4 IKR=0.24
+ VAR=28 ISC=1.06525E-11 NC =1.3728 RB =0.13 RE =0.22
+ RC =0.12 CJC=9.12E-12 MJC=0.3508 VJC=0.4089
+ CJE=27.01E-12 TF =0.325E-9 TR =100E-9
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Old 26th March 2004, 08:36 AM   #3
Bricolo is offline Bricolo  France
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This one rolls of at 4Mhz, that's better but still not close enough

Thanks for the help
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Old 26th March 2004, 09:28 AM   #4
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Datasheets for 2n2222/2n2222a report Ft of 250Mhz or 300Mhz.
Could there be something else, messing with your measurements?
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Old 26th March 2004, 09:34 AM   #5
Bricolo is offline Bricolo  France
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Isn't Ft the point chere you get 0dB gain?

I was talking about the -3dB point
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Old 26th March 2004, 10:03 AM   #6
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-3dB point from what level? Maybe you could show the application/testcircuit?
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Old 26th March 2004, 10:34 AM   #7
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Here it is

The -3dB point from the maximum gain, in an AC analysis.
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File Type: jpg tp.jpg (13.9 KB, 130 views)
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Old 26th March 2004, 12:50 PM   #8
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Given your circuit and the Zetex model,
yes i see -3dB low pass at 4.1Mhz
I also see -3dB high pass at 550Hz
Max Gain more than 44dB (160+)
Your source is set at 1V.
Is this what you intend to do?
Did you look at the signal at the output?
Did you use identical conditions in the real circuit as well?
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Old 26th March 2004, 05:01 PM   #9
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In the real life measurements, I got 44dB gain ant 560Hz high pass too

but the low pass was at 570kHz


No, the AC input was at somethink like 10mV. With 1V input the output is clipping
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Old 30th March 2004, 05:18 PM   #10
jcx is online now jcx  United States
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f_3dB of the transistor's current gain should aprox = f_t/h_fe

also consider miller effect when the gain is high - lower the source resistance for higher bandwidth - to the limit above

the f_3dB in this circuit is sensitive to several stongly varaiable transistor properties and >4x variation wouldn't be unexpected

a 160 MHz f_3dB must be a mistaken sim

Spice .AC analysis linearizes the circuit about the operating point and plots the small signal linear response, the source voltage/current levels are irrelevant and has lead many to declare a hopelessly cilpped, poorly biased cirucit to "work"
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