Sorry for the noob question, but does anyone know why this simple DC sweep doesn't seem to be working? As I increase the voltage over the gate of the nmos I would expect the drain voltage to vary and for the power source current to increase, but I don't see any change.

The gate terminal is floating. You should connect it somewhere.

Oh, so the DC card does not count as a voltage source?

you should make .dc Vpower 0 1.8 10m

Ok thanks. To be clear I am trying to sweep over the gate voltage, so I guess I would make another voltage source at G and then vary that source instead of trying to DC on the gate node directly

@Jesse Cirimelli-Low a

.dc

card does not add any voltage sources to the circuit. You need to set a voltage source on the gate, like

VG G 0 dc 0

then the

.dc

sweeps the voltage source:

.dc VG 0 1.8 0.01

Second the MOS instance should better specify at least W and L:

X0 D G 0 0 sky130_fd_pr__nfet_01v8 W=1 L=0.15

Thank you!