Opamps ?! That's brilliant !
I wanted to adjust my last comments a little bit, just to make it more
accurate and thus less confusing for other folks.
I was talking about the STI and WPE just to give an example of what
could impact your Vth but these new silicon manufacturing side-effects
raise on small technology nodes only.
Depending on the foundry, the STI usually comes with 0.25um nodes and
beyond and WPE with ~ 90nm, 65nm and beyond (even I saw papers on
0.13um, the little gain does not worth the efforts spend on the
design, that's my point of view). In addition, WPE is sup****ted with
BSIM4/PSP but not BSIM3.
Your AMS 0.35um is "too big" for this kind of effects ! I don't know
this process and I'm wondering if AMS is still using LOCOS isolation
instead of STI ?!!! never mind ! This data is just for your personal
knowledge ...
Hey Mobil !
Have you seen these equations yourself, give a quick a look at the
Appendix B of the BSIM3 pdf ... The Vth calculation stands on 2 pages
of very complicated mathematical which are not intended for a human
being reading but rather for simulators codings. The equation I
supplied above is good enough for a hand-made computation, let your
simulator does the complicated ones ... But If your are keen in
sinking your head into this, I can just say : GOOD LUCK ;-) ... I'm
too lazy for this, It's tiring me just in reading it !
Cheers,
Riad.
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