hi How can I measure transconductance gm of mosfet I coded l open-source-silicon #ieee-sscs-dc-23

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Title

Junbeom Park

04/26/2023, 6:08 AM

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

I want to use Gm/Id methodology. so I am trying to make techplots(Gm/Id, ft, ... etc)

Akira Tsuchiya

04/26/2023, 2:18 PM

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.

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