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LTSpice Homework

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revenge77

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Hi everyone, i need some help for my homework. To simulate these cirucits in the word document, and in order to find input output resistances and voltage gain in ac analysis, i should use spice. But here is a problem, how can i add npn and nmos having these parameters on the circuits. I could not find in the library of course. Generally can u help me for this homework. Im new in using Spice. Thanks !
 

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MrAl

Well-Known Member
Most Helpful Member
Hi,

Didnt they give you models in your course work?
 

MrAl

Well-Known Member
Most Helpful Member
Hello again,


Ok, because they quote specific values with specific names it seems that they want you to use a specific model that they must have given you earlier in the course. You'll have to find that model so we can go from there. For example, VA1 is probably the early voltage measured at a specific operating point, and i think the default value is infinite. And because they gave BE1 and the thermal voltage it seems they might want you to calculate IS so that you can include that in the model statement.

This might have been found in "First Homework" but where is this first homework?
 
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revenge77

New Member
Actually, first homework is the same questions we solved it on the paper, now they want the spice simulations of the same circuits. Can I find the voltage gain and input-output resistance values from spice after i drew the schematic ? Thank you for ur interest.
By the way it is not related to IS. It is neglected on these questions.
 

MrAl

Well-Known Member
Most Helpful Member
Hello again,


Well, if we could see that first homework and the work you have done for that assignment it might help understand what you need here. There are a number of possibilities so seeing that might help. We need to narrow down what they are looking for here.

So they said to ignore IS that's great, and see that is something that is almost ALWAYS specified in a spice model statement so without knowing that we can skip that we would never be able to do the problem with the bipolar. See what i mean now?

So we need that background information in order to help here.
 

revenge77

New Member
I handled the first homework. The second one will be different from the first. They just want to spice simulations of these circuits. How can i do that ? After i simulate the schematic the graphs are just straight lines for ac analysis :confused:
 

MikeMl

Well-Known Member
Most Helpful Member
post your LTSpice .asc circuit.
 
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