how to change the IDSS current of JFET transistor in Multisim?

Thread Starter

Rusty Rifle

Joined Dec 18, 2019
hi guys i have a project which needs to simulate the circuit on Multisim program but i don't know how to change the IDSS current (drain current for zero bias)
Thanks in advanced


Joined May 15, 2009
To change the IDSS, you will have to find the SPICE model for that device. Then use a text editor to change the value. But things are not as simple as that, even if you can find where Multisim keeps the files. I don't know, I don't use it.
Associated with the IDSS are other parameters like the gm and threshold voltage. These need to keep in step with the changes you make to the IDSS - in other words, if you want a different device model, measure the device you want to model, and at least determine the basic parameters that go with it. Do not change the IDSS alone. Create a new device name (i.e. file with the new name in it and containing your modified data) for your "special". Then you will have to get Multisim to add your new device to its SPICE library.
If you don't know how to do all this I recommend you don't try, and read up on how to do it first. Instead choose a different device as the previous poster said.