Hi, I have been struggling with looping to change w/l parameters of an nfet in sky130A using ngspice simulations. Somehow the variable used for iterating is not being found and hence not updated. Can someone please suggest what maybe going wrong here and how to correctly update variables and loop. The issues are described in the following link-https://docs.google.com/presentation/d/1S9xONsxgvmFeqJt2jmBulv1w4HZdwnfOBHNXvZVI_qc/edit#slide=id.g2014b667deb_0_6

try to open

sky130_tests/test_sweep_mos_w.sch

. this shows various I/V curves for a MOS tranistor at different W values. Sweeping parameters in ngspice is possible but tricky. Do not try to directly change model values with

alter

(i never got this working). Define some parameters for W and L,

(.param W=0.5

) use

alterparam

to change them:

alterparam W = $&w_act

(

w_act

is the loop variable. You need a

reset

statement after that alterparam.