Gm of transistor in hspice when it is called XM

[ankumar]

Hello,

How do I use hspice to gm using XL7 when transistor is called as an instance in netlist ? For example, transistor is called as XM8 instead of M8 .

Thanks
Anil K.

 

[dick_freebird]

There will me something like XM8^M1 as a device at the bottom
of it all, which can be probed in the usual way as long as you
"spell its name right". If you're using a GUI schematic driven
system then probe the drain current and take a close look at
how that's displayed (legend) or the "keep list".

 

[ankumar]

Thanks . I tried
.probe xl7(xm8.m0) to plot gm of transistor but it did not work. Is there any other way to plot gm/id for a FET

 

[dick_freebird]

I have no idea what "xl7" is or is meant to do, but I would
be looking for something like

deriv(I(xm8.mo.d)/deriv(v(whatever_the_gate_node_is)

in simulator-appropriate syntax for gm, and plot it vs
the drain current (or dump them both to a spreadsheet,
stepwise, maybe by a .print imported).

Start simple, until you can get at the drain current
and Vgs you're nowhere. Once you have that syntax right
the rest should be straightforward (other than the bit about
no idea regarding xl7).

 

[ankumar]

oops ..my mistake . I wanted to write LX7.