LTSpice question

Jul 11, 2014 5 Replies

I've noticed some LTSpice simulations indicate a higher than expected transistor current gain (HFE). I drew up a simple emitter follower circuit using a 2N3904 transistor and it indicates the emitter current at 1.6 amps (3 volts across 2 ohms in the emitter) and a base current at 24 milliamps for a HFE gain of 66. I didn't know a little 2N3904 transistor would operate at 1.6 amps and still have a gain of 66. What am I doing wrong?


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LTspice takes liberties with models to speed up simulations. Try a non-LTspice transistor model... they'll run just fine in LTspice and compare. Does the LTspice model have a term "IKF"? ...Jim Thompson

| James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 Skype: skypeanalog | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.

LTspice is super MAN, it knows no bounds!

Jamie

There sure is and that LIB entry does have it set to 0.4?

Jamie

"Jim Thompson" wrote in message news: snipped-for-privacy@4ax.com...

Yes, the LTspice modle has a term of IKF assigned to a value of 0.4. I found a non-LTspice model for the 2N2905A which was of interest and copied and saved the text using Notepad.. Not sure what filename to use or LTspice directive. Still working on those problems.

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Hey, LT Spice thinks a 1N914 can rectify 100 kilovolts!

John Larkin Highland Technology, Inc jlarkin att highlandtechnology dott com http://www.highlandtechnology.com

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