Why MOSFET IS OPERATED in Saturation region.................

[sandeep_sggs]

Why MOSFET IS OPERATED in Saturation region in most of the analog applications? please explain with some references..

 

[rajanarender_suram]

At the low-current end(weak inversion),
we do not want to use
the weak-inversion current
region either. The absolute values of the currents and of the transconductances become so small
that the noise becomes exceedingly large. Moreover, only low speeds can be obtained.

At velocity saturation region:
gm(sat) does not depend any
more on VGS either. It has
become a constant. This is
why this region is never used
by analog designers. The
transconductance does not
increase any more but the
current consumption does!!



This is why the highest
values of VGS used are the
ones in the middle current
region, close to the velocity
saturation region.