m is a bsim instance parameter which is defined as
'Multiplicity factor (number of MOSFETs in parallel)'.

nf is not a bsim parameter it might be a parameter of
a transistor subcircuit in your environment, (for number of fingers) .

If both are available for one MOS it's confusing,
maybe nf is used to calculate drain and source perimeter
and area for multifinger devices.

Bernd

NF and M are interchangable paraneters. You may use or one or another.
It is generally used for circuit driven layout and depends on the company methodology.

NF: you are defining Total Width and NF, and stating where you want the lowest (drain or source) capacitance.
In this case width per finger is calculated.
M: you are defining Width and M, Total Width is calculated.

mikki33 wrote on Jun 11^th, 2006, 8:55am:


Yikes!  That is a dangerously untrue statement, and it's a little hard to decipher the truth from what you wrote later.

"m" is generally defined as the "number of (identical) parallel devices" -- and implemented in the simulator, rather than in the model source code that one might get from Berkeley.

"nf" is, as Bernd wrote, a way of specifying some geometry information pre-layout.

But it's important to know that
 m1 d g 0 0 nch w=1u l=0.18u m=100
is definitely not the same as
 m1 d g 0 0 nch w=1u l=0.18u nf=100

The first will have 100 devices, each with a drawn width of 1u.  The second will have 100 poly gates each with a width of 0.01u.

Quote:


This makes sense to me, because the number of shared diffusion would for example affect the
amount of drain/source junction capacitance or the drain/source resistance that without the parameter nf
would not be taken into consideration by simulation.

But this means that I have to make layout decisions already during my early simulation phase.