Hi there!
I am currently looking for 2SA1708 and 2SC4488 transistor models to integrate into Spice, but I could not find any model on the web. Could you please help me if you have the related models? Or can you please give me feedback about what parameters are the most important ones to model these transistors correctly?

I really appreciate any help you can provide. Thanks...

 

The model for a transistor usually uses only "typical" specs. Then a transistor with minimum or maximum specs might not work when the circuit is built.
Many simulated transistors work perfectly even when the circuit has them severely overloaded.

 

If the application requirements are not critical, than you can use a model of a transistor with close to the characteristics of the one you want to use.

As AG noted, just make sure to design the circuit so that it can operate with the transistors at their maximum (worst-case) limits, not just nominal.

 

Or can you please give me feedback about what parameters are the most important ones to model these transistors correctly?

As AG says, Spice models are usually based on 'typical' specs (as per the transistor datasheet). Due to manufacturing tolerances there can be wide parameter value variations from transistor to transistor, of the same type, so any simulation can only be an approximation of reality. Exactly what do you mean by "correctly" in this context?

 

The simulator does not design the circuit, you do it.
You must design the transistor circuit with enough DC negative feedback to cancel the wide range of DC hFE that a transistor has in its datasheet. Opamp input current and input offset voltage ranges are also important specs for designing a circuit that the simulation models do not have.

 

hi,
I consider the 'typical' transistor specification as good guideline for general purpose circuitry.
Many manufactures determine a 'typical' specification figure, based on approx 68% test figures.

This link is a detailed explanation of some LTspice model parameters.

E

https://wiki.analog.com/university/courses/electronics/text/choosing-transistors

 

Thank you very much for your kind and helpful answers. I have found a similar transistor in spice and I will use that in my circuit.

Thanks again.

 

Thank you very much for your kind and helpful answers. I have found a similar transistor in spice and I will use that in my circuit.

Thanks again.

Which transistor did you decide to use?

 

Which transistor did you decide to use?

2SD1898 for npn and 2SB1260 for pnp transistor.

 

The data sheet NPN high voltage, high speed switching. Ft 120MHz, 1W
You need to know which category R S T for hFE or use a tester if available