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Here the value of drain current has been given as per the BSIM3v3 MOSFET model, but is there any reference where it has been shown how this value was calculated and what is the meaning of the symbols such as IDSAT0?


1 Answer 1


You can find a more extensive description of the BSIM3v3 model in this document. There are some formulas for Idsat in this document but I do not know if they can be used with the formula in your question.

In my opinion unless you're a modeling engineer there isn't much need to understand such a model in detail. Also, there are other models like MOS Model 9, 10 and 11 by NXP (they inherited that from Philips) and BSIM4. The EKV model is also an interesting one :-)

In general, for manual calculation you want a simple 1st order model as is described in most textbooks. So I find it a bit strange to grab a formula from BSIM3v3 but not explain the variables used in that formula.

  • \$\begingroup\$ I am actually an engineer in the making , so i am just curious to know how exactly the above formula was calculated. But if you are saying that unless you're a modeling engineer there isn't much need to understand such a model in detail, so i will keep this in mind. And yes i also found it strange that no reference has been given for the value of IDSAT0. \$\endgroup\$ Jun 18, 2015 at 17:43
  • \$\begingroup\$ Engineer in the making, I expected that :-) Models can be quite complicated so maybe the author of the book you got this formula from just used the formula "as is" without explaining. I think that's OK but he should have mentioned that. Complete PhD Thesis are written about MOS modelling so you can imagine it's complex stuff. Just having a basic understanding of how it works is enough for the average engineer in my opinion. \$\endgroup\$ Jun 18, 2015 at 19:31
  • \$\begingroup\$ ok sir,gotcha :) \$\endgroup\$ Jun 19, 2015 at 16:16

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