Using fingers in Hspice

[dream_taker]

If we use fingering in layout the Drain/source cap is reduced by that factor. Is it the same case when we use Hspice. Imagine I set M=2 in hspice which means I am using a finger of two, will hspice consider half the cap at Drain/Source?

We also give diffusion area and diffuison periphery values in schematic for a transistor. So which will Hspice takes into account ?

 

[yeewong_su]

Yes. The Hspice can do it. and it work like that

 

[flushrat]

how does hspice define PS PD AS AD for different layout purpose?
Fox example:
we try to plot a pmos: MP0 D G S B pch w=1u l=0.18u m=2
One way, we draw two pmos(2/0.18) with drain sharing.
So PS=2*PD AS=2*AD for each pmos.
Also, we can draw two pmos separately.
So PS=PD AS=AD for each pmos.