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Hello everyone,

I wanted to ask if there is a tutorial for generating gm/ID charts using xschem and ngspice?

And if there is an avalaible script for generating them?

Thanks

You can plot the gm and gds graphs similar to id graphs

. save @m.xm1.msky130_fd_pr__nfet__01v8[gm]
. save @m.xm1.msky130_fd_pr__nfet__01v8[gds]
Add these command below .op command while performing dc analysis. Here m1 is transistor number M1

Now run simulation and in ngapice window type below commands
let gm = @m.xm1.msky130_fd_pr_nfet_01v8[gm]
let id = @m.xm1.msky130_fd_pr_nfet_01v8[id]
let gds = @m.xm1.msky130_fd_pr_nfet_01v8[gds]
let a = gm/id
setscale a
plot gm/gds
plot id/W

<@U03BV4U067N> <https://github.com/idea-fasoc/OpenFASOC/blob/main/openfasoc/mos_char/gmId.netlist>

<@U021BTRSZ5H>  <@U01819B63HP> I am using ngspice in batch mode and trying to use let command as `.let id = @m.xm1.msky130_fd_pr_nfet_01v8[id]` but it seems to be not working. Can you please confirm if `let` command can be used in batch mode or not ?

<@U01TK0ML9H9>  It's better to use let inside  . control  and  . end block
rather than using  .let  can you share the control block you are using.

nmos_batch.spice

I am trying to plot gm/id curve by running ngspice in batch mode. please check my netlist and provide feedback. I am not comfortable with control block in ngspice hence using it in batch mode.

What error are you facing? Can you post a screen shot.

On line 22 just write  .save all. On next line write  . save @m.xm1.msky130_fd_pr__nfet_01v8[gm]
and then on next line write  . save @m.xm1.msky130_fd_pr__nfet_01v8[id]