I'm trying to incorporate a SPICE model of an NMOS IC, the ALD1106. I've used it before in class, but it's been so long that I've forgotten how to incorporate the files into LTspice in order to properly use it. Luckily, I found some SPICE models from ALD's website located below:

Link to SPICE models here

I've extracted the files, and I've included the following files in my schematic with the '.include' command: ALD_TECH.TEK, IC_TRAN.lib, and Ic_mod.lib. I've also opened up IC_TRAN and created a component model of the 1106 with the correct pins and everything, but I consistently get a warning that it can't find the definition of model "DPS". Can anyone please give me some advice on what to do next?

  • \$\begingroup\$ Those are PSpice models, and while the library (.lib) can (or should) be usable in LTspice, the symbols have to be created, or used from the internal database. However, looking through the library, I don't think LTspice will recognize those ncg, pca, and dps, and may have to be edited manually. \$\endgroup\$ Commented Sep 12, 2019 at 14:50
  • \$\begingroup\$ The linked 1106 model references two other models, ncg and dps. You must find those models, as well. Once you have them, you can combine them with the existing 1106 model to make a full subckt. Unfortunately, they require me to create an account and sign in to do more work. And I won't do that. But you need to find those models. They are probably pretty standard models. But they weren't included in the ZIP file I examined. (Or, at least, I didn't readily find them -- oh, well. Never mind. I just found them in a file called Ic_mod.lib.) \$\endgroup\$
    – jonk
    Commented Sep 13, 2019 at 6:54
  • \$\begingroup\$ You will also need to create your own symbol from LTspice. The model requires 5 pins, not four. (Because there is +V pin.) So you will have to fabricate your own symbol. (There is an included diode which ties to the 5th pin.) \$\endgroup\$
    – jonk
    Commented Sep 13, 2019 at 7:13

1 Answer 1


dps is a custom diode model used by the NMOS by ALD. My speculation is that they are using N-type substrates, so there will be a junction diode between a NMOS body (presumably p-type well) and a PMOS body (n-type substrate). Therefore pin #5 will be shorted to PMOS's body or, if PMOS is absent in your circuit, the highest voltage rail.

By finding the string dps in ALL of ALD's library files gave me a few useful matches, that are .model sections. They are in 1108.lib and 11XXYY.lib. They should come from ALD1108xx and ALD2108xx libraries, and all model sections are identical.

You may download your own library files. I won't show them here.

Honestly, if all the body terminals of your NMOS and PMOS are always connected to DC voltage rails, I doubt if the additional diodes would make any difference.


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