I am
working with 90 nm CMOS at the
moment and have some difficulty with the hand calculations. I am trying
to

hand
calculate values, similar to
what's seen in Table 9.2, using short-channel equations.

You
can't use MOSFET current-voltage
(IV) equations to get small-signal parameters for hand calculations in

nanometer
CMOS since there aren't any
equations that are accurate. If there were the SPICE models would be
much

simpler.

You
have to use experimental data to
get small-signal parameters (*g _{m}*,

data
is easiest to use in plot form from SPICE simulations or from the electrical information you get from
the
foundry.

All
SPICE models nowadays are
determined experimentally so the simulations give you the experimental
data
(see, for

example,
pages 298 and 299 in the
book). The parameters of the SPICE model are "curve fit" to match the
experimental

data.
The designer can then take the
model and generate plots, using SPICE, for specific operating
conditions and

thus
hand calculations.

So,
why didn't (or can't) we use, for
example, Eqs. (9.56) and (9.57) to do hand calculations? Many reasons.
In

Eq.
(9.56) vsat,
for example, isn't a constant but a function of device size, *V _{DS}*, and

aren't
constant values and change
drastically with changes in the voltage across the devices. The
equations are

useful
to see the reduction in *g _{m}*
or

since
they can't be used for good
modeling of the devices.

Note
that I assumed you weren't talking
about using long-channel (square-law) equations, page 271, for
nanometer

CMOS
since that is fundamentally wrong
as discussed in the book.