Simulation of MOSFET noise with ngspice

[0y8w1x]

Environment

• Klayout Version: not applicable
• OS/Platform: Ubuntu 22.04

Actual Behavior

I tried to do a noise simulation of a single common source transistor, but found the noise to be 0. In case the schematic is incorrect or I use the noise analysis wrong, please let me know. A simple DC analysis works just fine, so the general setup should be working.

My circuit looks like this:

And when I plot the onoise_spectrum/inoise_spectrum aswell as the total integrated noise I get the following:

[bmurmann]

You are measuring the output noise at a node that is pinned to 1V, so I am not surprised that the result is zero. What are you trying to do?

[0y8w1x]

You are measuring the output noise at a node that is pinned to 1V, so I am not surprised that the result is zero. What are you trying to do?

Oh yeah that was a stupid mistake. I want to measure the intrinsic noise of the MOSFET

[KrzysztofHerman]

@0y8w1x could you please provide a correct testbench with some results. After that we could close the issue with a working example.

[dwarning]

Maybe these qucs-s/ngspice (NGSPICE_OSDI_DIR env variable have to be set) examples can help to close the issue:

lv_nmos_NOISE_id.sch.txt lv_nmos_NOISE_vd_vg.sch.txt

[KrzysztofHerman]

@dwarning we provide a sample .spiceinit, which sets the location of the OSDI file so you do not have to reference it on the schematic. The only thing you have to do is to create a symbolic link to this file under your $HOME direcory. I will also add some more controls to setup the noise plot type.

[dwarning]

Sorry, it was not the emphasis of my post. Anyway - thanks for hint. What about induced gate noise. There are data and test benches available?

[0y8w1x]

thanks @dwarning for the example, I reproduced it and it works great.

[dwarning]

Another test case in a 50 Ohm environment NF, NFMIN and Rgn =f(Freq)

[sergeiandreyev]

Hi @0y8w1x, do you have additional questions, or we can close the issue?