Linear Region: (triangle sign) (VDS<Vg), Vg = VGS -Vth
ID = 2K*(VGS – Vth) VDS – VDS^2]
Saturation Region (VDS >Vg) (Rectangle sign):
ID = K*(VGS – Vth)^2 *(lambda *VDS+1)
K= transconductance (constant)
Kp= transconductance parameter (MCox)
constant .
for N cnannel MOSFET Kp = Kn and for P channel MOSFET Kp = Kp.
Note: Kn~ =3*Kp
* Small MOSFET: 20 to 200 Micro A/V^2
*Power MOSFET: 1 to 10 A/V^2
K = (Kp/2).W/L
gm (forward transconductance) measured by Siamon (S) =A/V
gm = 2K*Vg
Lamda: length modulation factor. lamda = o means flat(no change in ID in saturation region). Lamda (.01 to .1) = LD in Saturation. check ID -VDS curve.
Note:
1. if MOSFET has no bar or triangle its OFF
2. Lamda can be assumed 0
3. Small MOSFET (<2AMP) Width / Length ≈ 100
4. Medium (2 to 5 Amp) W/L = 500
5. Large (20 to 50 A) W/L = 100,000
6. Very large (> 100 A) W/L = 500,000
7. m is milli, n is nano, u is micro
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