Joe McElvenney wrote:
Hi,

Agilent's (HP) AppCAD may be what you are looking for. The
current version is 3.02, I believe, and it is free.


Cheers - Joe


That's a good program, and there is tons of
stuff there.

But i'm not certain I can get large
signal impedances out of it. I mean,
when they give large signal impedances on
a data sheet, it's usually done by matching
the input and output on the bench, with
cut-and-try techniques, and then removing
the DUT, and using a VNA to measure the
what the transistor "sees" on both sides,
and then taking the conjugate of this, and
calling this the large signal impedance.
Matching to these usually gives you
good results.

How close Z11=((1+s11)*(1-s22)+s12*s21)/((1-s11)
*(1-s22)-s12*s21) will be to the stated large signal
impedances after you convert
it to a series equivalent impedance on the Smith
chart, I don't really know. It won't surpise me
if it doesn't come too close, as the s-parameters
are small signal.



Slick