# Calculating idsat from process models

1. Nov 12, 2011

### ClearWaterNW

Hi, if anyone can help on this issue it is much abliged...

1. The problem statement, all variables and given/known data

Here are the model parameters...
VTH0 (VTH NMOS) = 0.7 to get everything even...
U0 (NMOS un) = 533 cm^2 / V sec or 533000000 um^2 / V sec
t0x = 1.41 * 10^-8 m or 0.0141 um
eox = 3.97 * 8.85 aF/um or .000035.1345 uF / um

Also...
VDD = 5V
W/L = 10/2

2. Relevant equations

Idsat = 1/2*KPn*W/L*(VDD-VTHN)^2

3. The attempt at a solution

Must solve for Kpn = un * eox/tox first...
Using the values above I feel I get an unreasonable value of about 1.33 uA / V^2
This results in an Idsat of roughly 10 uA

A more reasonable result would give me a KPn of roughly 100 uA/V^2

There must be something wrong with the process model or I am missing a parameter or something. I am positive my units and calculations are correct as I have been through this problem many times.

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