Hi,
I used the QSPICE mosfet model generator to created a model for the BSS138.
The datasheet I used is the one from TSC: https://www.mouser.com/datasheet/2/395/BSS138_A2007-2064302.pdf
The Vto value in the generated model is -53.2. Doesn’t this indicate that something went wrong with the model generation process?
The behavior I get from it when I use it in a schematic is strange.
When I crunch and test at the last step (the “Gate Charge” tab) I get a graph that doesn’t match the datasheet (Note the attached Gate_Charge_Test_Result.png).
.model of BSS138 can be found in mosfet library in ltwiki.org
I sorted and merged multiple .model libraries, here is the line for BSS138
SPICE-MOSFET-KSKelvin.lib#L921 · KSKelvin-Github/Qspice
Comparing the Onsemi and Taiwan Semiconductor BSS138, their output characteristic curves are quite different. The Taiwan Semiconductor curve doesn’t make much sense to me. You had better check if your actual device follows that curve.
Onsemi datasheet
BSS138 - N-Channel Logic Level Enhancement Mode Field Effect Transistor
Taiwan semiconductor datasheet
https://www.mouser.com/datasheet/2/395/BSS138_A2007-2064302.pdf
Thanks @KSKelvin
It seems this is it. I did the process again using the graphs from the onsemi datasheet and it works.
However I had to use the values from the TSC datasheet, since the onsemi one doesn’t contain all the values needed (e.g. Reverse Recovery Charge is missing from onsemi).
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