I'm trying to do a simulation with a subcircuit, and I've narrowed down the issue to the V() function.

The simulation fails with the message 'can't find definition of model "V" '

Here is the spice library with the subckt (RXD_33_2_TYP) (The library was from an IBIS model converted to SPICE using microcap)

test.lib to troubleshoot issue

Original iso7421.lib

enter image description here

  • \$\begingroup\$ Please post the entire netlist and models \$\endgroup\$
    – Voltage Spike
    May 10, 2019 at 23:46
  • \$\begingroup\$ Added, see original post. Thank you \$\endgroup\$
    – Joel
    May 12, 2019 at 15:59

1 Answer 1


You need to set the resistance value of the variable resistor to R={V(IN)*100}.

The resulting netlist line will look like: Rdoesntwork IN OUT R={V(IN) * 100}

  • \$\begingroup\$ That works yes, thank you. sadly this means I have to go thru a large subckt and change these manually. Not sure why LTSpice requires this extra "R=" wile the model was provided without it. \$\endgroup\$
    – Joel
    May 12, 2019 at 0:03

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