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Is the lambda here a channel-length modulation parameter?

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isaacnewton

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LAMBDA ?

Hi,

I have a question about Channel-length modulation parameter - lambda. I copied the following from:
www.mosis.org/cgi-bin/cgiwrap/umosis/swp/params/tsmc-025/t4cs_mm_non_epi-params.txt

Is the 'lambda' there channel-length modulation parameter? Thank you.


Copied from mosis.com
Code:
-------------------------------------------------------------------------------------
COMMENTS: Poly bias varies with design technology. To account for mask
           bias use the appropriate value for the parameters XL and XW
           in your SPICE model card.
                       Design Technology                   XL (um)  XW (um)
                       -----------------                   -------  ------
                       SCN5M_DEEP (lambda=0.12)             0.00    -0.04
                                     thick oxide, NMOS     -0.01    -0.04
                                     thick oxide, PMOS     -0.06
                       SCN6M_SUBM (lambda=0.15)            -0.06     0.00
                                     thick oxide, NMOS     -0.10     0.00
                                     thick oxide, PMOS     -0.15
-------------------------------------------------------------------------------------
End of copy
 

arunragavan

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Re: LAMBDA ?

did u check the velocity.. velocity saturation is inversely proportional to channel length modulation

take a look at this

h**p://www.inblue.com/gEDA/tools/acs/man/node74.html

with regards,
 

eda4you

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Re: LAMBDA ?

Hi!

lambda could also been the min. lenght (critical dimension). Some foundaries define their design rules not in absolute values (µm or nm), w but in multiple of λ.

I don't think that channel modulation is the lambda. The modulation varies in short channel devies over a wide range.
 

skal81

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Re: LAMBDA ?

I don't think the lambda written there correponds to the channel modulation. It makes very little sense because:
1) This is a BSIM3 model. The lambda parameter is no longer used. (it's for MOS model 1 or model 2)
2) The part you've quote refer to the variations in W & L from drawn values.
In BSIM3 there is no explicit parameter for the modulation channel effect. However, you have the RDSW parameter that correspond to an equivalent drain source resistance. For more detail I suggest you refer to the BSIM3 manual.
Hope it helps
 

isaacnewton

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skal81

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Re: LAMBDA ?

The RDSW for NMOS is 200, for PMOS is about 1780. I looks like the values for RDSW - 'equivalent drain source resistance' are very small.
I don't remember the exact formula, but to get the drain-source resistance you have something like:
Rds = RDSW/(1e6*W).
The principle is that the small W the higher the resistance. However as I said it does not correpond to the channel modulation effect, but it's the parasitic resistance that appears in submicron.
 

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