@User Resistors in spice netlists can be defined by a model, like in

R1 node1 node2 resmodel r={expr}

The resistor model may define some parameters like temperature coefficients: .

model resmodel tc1={expr} ...

. Problem is that ngspice (as@User found in his tests) does not understand this syntax. In all but one case the

tc1={expr}

in resistor models contains a single parameter, so the numeric value of the parameter has been written directly into the resistor line, without using a model:

R1 node1 node2 r={expr}  tc1=number1 tc2=number2

There is one case where the tc1={expr} does not evaluate to a fixed number but depends on more than one parameter:

tc1 = {-1.47e-3-5e-7*sky130_fd_pr__res_xhigh_po__var_mult*rsheet}

. What previous patches have done is to replace only the leading -1.47e-3 into the resistor line: tc1 = -1.47e-3. This is not correct. My suggestion is to replace line 60 in sky130_fd_pr__res_xhigh_po.model.spice:

+ tc1 = -1.47e-3

with:

+ tc1 = {-1.47e-3-5e-7*sky130_fd_pr__res_xhigh_po__var_mult*rsheet}

I am doing a test right now if ngspice is ok with that. Will let you know asap.