Why is R1 Current so Low?

I admit that this simulator is new to me. Why is the current so low in R1?
Why is the device not turned on hard?
Do I have to give additional parameters?

Hi, Brian.

Is the source pin attached to the ground wire?

If so, can you post the schematic?


The schematic is posted. At least I can see it…

Well, I see an image, not an uploaded/attached *.qsch.

FET.qsch (4.5 KB)

OK, sorry… I think it’s loaded now.

Are you new in spice simulation?
One of the major parameter control Id vs Vgs is Kp for NMOS model.
Your NMOS name is NMOS, which mean you are using NMOS default parameters. You can add a .model statement to modify Kp. In Qspice HELP, it mentioned Kp default is 2e-5 A/V^2. For example, add .model NMOS NMOS KP=2e-3, you can see current is reaching ~20mA (increase Kp can give a more aggressive curve). But generally, we are not using default model except you knows exactly what you are doing.

You can bring Qspice default NMOS library to pick a FET model.
What you can do right now is that, right click on M1, select “Show Symbol Properties”, add “NMOS.txt” in Library File. Now, right click on M1 again, you get a “Selection Guide”, and here you can select a device model from Qspice standard library. If you need other .model for NMOS, you can goto For LTspice users. Libraries of models, examples, etc (ltwiki.org) to get VDMOS model. This library is from @bordodynov , and I believe he spent a lot of time collecting these useful library for spice community.

Yes, I’ve been using the simulator for about an hour. I knew about “models”… but had no idea how to hook them. Thanks for your information!

As you are new and may want to play with a more complete library likes what I quote from @bordodynov, here is a quick way how you can get selection guide to load from a user library for Qspice standard symbol.