Hi everyone, is there any way to find µncox and µpcox value in cadence, if so , do let me know, thanks in advance

sri.sagar wrote on Dec 22^nd, 2011, 10:59pm:



It is buried in the transisor models in some cases.
(depends on the transistor models)

Another method is to use a set of transistor bias curves
and reverse engineer them out of there.

As a general rule, these don't get used too much
except as an academic illustration.

hello,
most of the times it increases (from theory point of view).
One thing i want suggest is if you want to continue in circuit design better start use gm/id method rather than struggling with finding about process parameters.
you can refer ee214 lectures notes by Boris murmon

Thanks,
raj.

Here is the way which i had followed,  and correct me if I am wrong as  am a newbie to this analog field  

Steps to calculate µncox value in cadence

1). Consider a CS stage
Assume gain Av = 5v/v, RD = 10k, ID = 100µA, µncox = 150µ
                         Gain AV=gm RD
gm = AV / RD
gm = 5/10k = 0.5mƱ

But                  

gm = sqrt (2 µncox (W/L) n ID)
 (W/L) n = 8.33 ≈ 10

So set W=10µ and L=1µ
     

   
After simulation, the gain(new) AV = 5.2 ≈ 5 (initially assumed)
gm(new) = 541.3 µ ≈ 0.5m (initially assumed) and   ID(new) = 111µ

Based on gm (new), ID (new) and (W/L) n (old), we can calculate µncox as
gm = sqrt (2 µncox (W/L) n ID)
µncox = gm2/ (2(W/L) n ID)

µncox=132µ

The procedure remains same for µpcox and i got the value as                  

µpcox=32µ

hello sri.sagar,
in your post you have calculated gm by normal square law which is true only above 180nm (some rough number), which is gives very wrong results with 90nm and below. I strongly encourage you to proceed with gm/id, if you are still interested to do by this kind of calculation fist find the power of the Vgs-Vth in the current expression, for this refer

http://dit.upc.es/lpdntt/biblio/BREUS/SAK90a.pdf

Thanks,
raj.