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I'm looking to use an NTE222 (dual gate mosfet) in a design I'm pondering. I've also very recently upgraded from my slide rule to LTSpice (yes, I've been living under a rock, but I'm enjoying having finally crawled out from there!)

Looking through the library of components that came with the original installation of LTSpice, I don't see this device. It's possible I don't know how to search, or the category I should be looking in.

If it's there, can someone point me at it?

If it's not there, does anyone know if there's a model I can obtain from somewhere?

And if not, does anyone know how I might create my own model for it?

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    \$\begingroup\$ You're not wrong, it's not in the default installation database. You could try asking the manufacturer (make sure it's not encrypted or, if it is, it's for LTspice, not something else; it will not work otherwise), or searching the Files/ area in the LTspice group for it (I just tried and I saw none, but maybe you'll have better luck), or, if you haven't done it already, the web. I'd also try this site, it has a large collection of models and libraries. \$\endgroup\$
    – a concerned citizen
    Commented Dec 29, 2021 at 17:55
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    \$\begingroup\$ Dual-gate small-signal MOSfets have stymied me too - my workaround uses two JFETs in series. That is, the drain of the bottom one connects to the source of the top one. The default LTspice library has a few appropriate JFETs. Not perfect, but might be easier than chipping a new model out of rock. \$\endgroup\$
    – glen_geek
    Commented Dec 29, 2021 at 18:40

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Usually the part supplier has a spice file that can be downloaded, if so you can add a third party model to LT spice with some work (LT spice is just a GUI for spice and spice runs off of text files)

I couldn't fine a product page for the NTE222 and there were no spice files in that datasheet. (its likely that the NTE222 is just a repackaged or resold fet). This means you would need to find an equivalent model or build your own from parameters in the datasheet. If you are only using the NTE222 to switch and its something like a low current (don't have to worry about heating) or the application doesn't have switching time requirements, you could probably just find two other mosfets from the list with simmilar characteristics (like RDSon VDS and capacitance ect) and use those as substitutes.

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  • \$\begingroup\$ Sadly for me, I was hoping to use spice to understand this device; my shortcoming in that respect will make it hard for me to produce a model that's useful :( I'll go looking to see if another dual gate device seems comparable, though from @glen_geek's comment above, perhaps there aren't any of these things in the model set. \$\endgroup\$
    – Toby Eggitt
    Commented Dec 30, 2021 at 3:01

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