Croaker
|
Qi/Ci is positive for both PMOS and NMOS (the interface charge, Qi, is positive). So, the Vfb term you mentioned is more negative for a larger contamination (Qi/Ci is bigger)
Vfb = Vms - Qi/Ci Vth = Vfb + ...
For NMOS, Vth is more negative (threshold is lower). For PMOS, Vth is more negative (threshold is higher, since it has a more negative Vth)
I.e.
VthNMOS = 1 - 0.1 = 0.9 (better) VthPMOS = -1 - 0.1 = -1.1 (worse)
I assume you want minimum threshold voltages. This might not be desirable for low leakage currents.
I hope that cleared things up.
Cheers, Marc
|