channel length modulation

[airace]

Hi experts...
I am trying to characterize a MOS for it's design parameter..
Can you tell me How I can measure 'lambda' using analog artist?

Regards,
@ir@ce

 

[airace]

....also, I did try the method given in Hollberg Appendix..
which uses the y=mx + b method.....I could not figure out how is measuring 'b'....
........if someone has done this...can you please throw some light on it?

Thanks in adv
@ir@ce

 

[micel99]

I don't think you can find such a parameter in model file.

 

[dwang_w]

you can caculate the inpedence through outputcharacter curve, then
R=1/I*lamda,so you can got the lamda

 

[v_naren]

1) plot of o/p resistance vs Vds for different values of Vgs

2) o/p characteristics

3) Lambda in zoomed in view


all for a 0.18um process

 

[elektroda_2004]

Lamda is not specified in most of the recent process files so in order to measure a realistic value for lamda so u can use it in your claculations plz do the following:
1. using schematic arc. place the transistor symbol of interest, voltage source, current source, and Vdd or gnd node (for PMOS or NMOS)
2.Connect the voltage source to be ur Vds and the current source to be ur Ids
3.Run a DC sweep for Vds and plot the corresponding Ids
4.Now that u have a Vds-Ids curve use the regular proceedures to calculate lamda from the curve

 

[Puppet1]

Lamba is the slope of Ids/Vds curve.

 

[v_naren]

Please note that it is not so straight forward to "get" the lamba directly from cadence even using the formula

lamba= 1
Id x Rout

u need to use a really really amazing trick...to get Rout first directly by making cadence give it to you when u sweep...it is also extremely useful in getting even the other model internal component values.

please see



It is most useful for models using bsim3 and where the short channel effect plays havoc!!!

I have given an example of what can be done using this technique in context of this message thread.

Do reply if u need some more explanation.....I have also given plots of the rout as a function of vds and vgs and hence the lamba too