weak inversion current

[rosaeidi]

Hi

I'm confused with NMOS and PMOS transistors in subthreshold region.

Which of them has the higher current value, for a given value of Vgs?
Which of them has the higher subthreshold slope?
Which of them has the higher value of threshold voltage?

I'm working with 90nm Tech.

Rosa

 

[yadavvlsi]

In weak inversion the current varies exponentially with gate-to-source bias VGS as given approximately by .
where ID0 = drain current at VGS = Vth, the thermal voltage VT = kT / q and the slope factor n is given by n = 1 + CD / Cox, with CD = capacitance of the depletion layer and COX = capacitance of the oxide layer. With the same physical (W and L) and process parameters (dopping levels) NMOS will have higher drain and sub-threshold leakage current as the mobility of electrons is higher than holes.

Slope in sub-threshold region will be same as both CD and Cox are same in both cases.

Threshold voltage mainly depends on: Gate insulator thickness, Substrate dopping levels, Gate material, temperature.. So threshold voltage will also be same for NMOS and PMOS for same physical and process parameters.


MOSFET - Wikipedia, the free encyclopedia
Threshold voltage - Wikipedia, the free encyclopedia