I've converted an IBIS model to a SPICE model using microCap, and am trying to simulate that subckt with LTSpice.

Using LTspice, I get an error with the subckt in the library.

"u1:g1: Unknown circuit node: "u1:xvkdr.vkdr" requested in behavioural source"

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It cannot understand the V() function used in this way "V(XVKDR.VKDR)" Which is referencing a specific voltage net (VKDR) within the subckt (XVKDR).

Here is the LTspice project with .lib

LTSpice project

Thank you


1 Answer 1


In LT spice V() means the voltage of the node, I() means the current of the node.

For example, if I wanted to use a net named Vout.1 in an equation I would write this:

Value = V(Vout.1)*5

extracting the current only works on ports to parts, or two terminal parts

Value = I(R1) Value = I(U1:OUT)

As far as I know, spice or LT spice do not support IBIS files, you need to convert the files to spice. This could be done with the tool described here and/orhere

SPICE considers xvkdr.vkdr to be a single net name, I don't know how IBIS files work but it looks like IBIS considers xvkdr to be a component and vkdr to be a net. A workaround would be to go through the file and make sure there are only net names and rename all of the IBIS conventions to spice compatible conventions as spice only uses net names, there are no "sub-net" names.


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