Hi,

I recall having seen this somewhere on the forum but cannot find it. I would like to plot
the fT of a MOS transistor using the operating point information as I sweep the operating
point using parametric analysis (say by varying Vgs).

However, the list of parameters available does not include fT. It does include Gm, but then,
the various other parameters are not available in a convenient form and there are only the
partial derivatives (Cgs, Csg, etc.).

How can one get a plot of fT?

Regards
Vivek

Vivek,

  Attached is an example testbench illustrating how to measure ft.
A pseudo-Wilson mirror is used to servo the base[gate] voltage so
that the collector [drain] current matches the reference current.
Please look it over and let me know if you have any questions.
BTW, the basic methodology can be extended to other measurements,
for example, Noise Figure. Also this testbench directly mesures the
ft so it can be used with in-line subcircuit-based device models, etc.

                                                              Best Regards,

                                                                 Sheldon

sheldon wrote on Mar 6^th, 2007, 2:59am:


MOS transistor Drain current is not determined by Gate current.  How is your test method supposed to work?

Hi

attached the finding method for Ft of nmos, the ugb of the i_probe current ft of the transistor

Rgds
Raja