hi. How can I measure transconductance(gm) of mosfet? I coded like below. but it was only ZERO.

I guess, the reason is that the transistor is in a subckt. In the netlist, the transistor M1 is defined like

XM1 net2 net 1 ... nfet_03v3 ...

and the subckt

nfet_03v3

is defined in the library sm141064.ngspice. In the definition of

nfet_03v3

, transistor is

m0

. So I tried @xm1.m0[gm], but it didn't work... I am not sure this is the best way, but I use

deriv

to calculate gm = dId/dVgs. Attached is my way to plot gm/id.