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Setting Vbe in PSPICE?

Hi!

I would like to set Vbe to 0.8V to a transistor in PSPICE. How should I set it? I click on the transistor, I click on Edit->Model, then Edit Instance Model(Text), then what? Which parameter to set Vbe?

Thanks.

Reply to
Emily
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Vbe in a working circuit is determined by many things, not just a single parameter in the Spice bjt model. Try varying VJE to get the performance you expect. (I'm assuming that Spice2 uses the same parameter name as Spice3 here, but if not, change the "B-E built-in potential," or switch over to a Spice3 based simulator such as the free and very nice LTSpice.)

Cheers, Tom

Reply to
Tom Bruhns

In the old versions of Pspice, it would be VJE or PE (either will work).

Reply to
whit3rd

"whit3rd" AND Tom Bruhns.... shame be upon thou...

VJE/PE sets the curvature of junction CAPACITANCE

IS (primarily) sets VBE versus current.

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
I love to cook with wine.      Sometimes I even put it in the food.
Reply to
Jim Thompson

Oooooh that's interesting. Does it apply to deeodds as well?

Hold that thought I'll have a look....

DNA

Reply to
Genome

Yeth ;-)

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
I love to cook with wine.      Sometimes I even put it in the food.
Reply to
Jim Thompson

You can set Vbe outside the .MODEL statement A simple example ... YOURCIRCUIT.CIR Vbe 1 0 0.8V Q 1 1 0 QNPN Vc 2 0 1V . . . etc . . . .MODEL QNPN NPN(Is=10fA Ikf=150mA Isc=10fA Bf=150

  • Br=3 Rb=1ohm Rc=1ohm Va=30V Cjc=10pF Cje=15pF) .PROBE .END

lemonjuice

Reply to
lemonjuice

Sheeeeesh! etc, etc, etc... ;-)

Vbe, as "lemonjuice" has shown in his/her netlist is a VOLTAGE SOURCE... thus _forcing_ that potential.

The OP, if I understand her correctly, wishes to have a device with Vbe = 0.8V at some defined current level.

If she wants Vbe = 0.8V at Ie = 1mA, then she should set IS =

43.36e-18

IS = Ie*(e^(-q*Vbe/(k*T)))

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
I love to cook with wine.      Sometimes I even put it in the food.
Reply to
Jim Thompson

(Slaps forehead...) (Blush) yes indeed. Thanks, Jim. However, ISE, RB and RE also have an effect, the resistances especially noticable of course at higher currents.

Cheers, Tom

Reply to
Tom Bruhns

And IKF (current crowding at the periphery of the emitter).

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
I love to cook with wine.      Sometimes I even put it in the food.
Reply to
Jim Thompson

And then find someone to design the dopant concentrations, 3D topology, and then fab the darned thing.

Jon

Reply to
Jonathan Kirwan

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
I love to cook with wine.      Sometimes I even put it in the food.
Reply to
Jim Thompson

Well I didn't see she/he mention any current level ... or did I miss something? BTW having Vbe = 0.8V is equivalent to have a voltage source of 0.8V between the base and emitter. I heard its going to hotter tomorrow in Phoenix ... take your hat or wig with you . :)

lemonjuice

Reply to
lemonjuice

Really ??

I think you should leave the transistor instructions to me ;-)

I'm heading out the door in just a few minutes to Tombstone, for the

150th Anniversary Reenactment of the Gunfight at OK Corral ;-)

Max temperature 80°F, night time low of 45°F.

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
I love to cook with wine.      Sometimes I even put it in the food.
Reply to
Jim Thompson

Let us know how it compares to the original. ;-)

--
Service to my country? Been there, Done that, and I\'ve got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida
Reply to
Michael A. Terrell

[snip]

LOUD! In the original, 30 shots, three dead, two wounded seriously... elapsed time 35 seconds.

I earlier incorrectly said 150th Anniversary, it was the 125th, but they reenacted everything, including the funeral procession... about

10 city blocks long... quite the deal for 1881.

Only the family wore black, the celebrants wore white... since the Clantons and the McLaury Brothers were Democrats.

No joke, that is for real ;-)

Virtually NO Democrat candidate's signs visible in all of Cochise County, so I suspect bad blood to this very day.

Altogether I took 58 photographs. I'll post them when I have a free moment.

Also saw a marvelous amateur rendition of HMS Pinafore, performed on the same stage as it was in 1881.

The reenactment of HMS Pinafore had the Earps arresting the actor, portraying the admiral, for public drunkenness, and Doc Holliday stepping forward, "I'll be your huckleberry", and taking over the part. I suspect this was only a gag, but I'll inquire to see if it really happened.

Had a lot of fun, ate a lot of steak and prime rib (try and get anything else ;-)

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
I love to cook with wine.      Sometimes I even put it in the food.
Reply to
Jim Thompson

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