Ion/Ioff of a mosfet plzzz reply fast

[gmahajan027]

hi

I wanted to know how do we define Ion and Ioff for a mosfet .

I am confused as to is there a particular voltage above threshold which is considered as volatge for I on and is 0 volts gate voltage considered as Ioff

I will be thankful for any help

 

[Colbhaidh]

Ion is specified as the Idsat for the particular gate voltage (usually max Vgs) for for a 1.8V mos Ion is for Vds=1.8V and ay Vgs=1.8V.
Ioff is the IDss leakage where Vgs=0 and Vds=max so again for the 1.8V nmos this ould be Vgs=0 and Vds=1.8V.

 

[gmahajan027]

cool ..thanks for the reply
if i have a device of Vt=0.150 volts

then what should be volatges at which i should measure current to get Ion/Ioff ratio

Added after 40 minutes:

also I wanted to ask if there is any definition f Ion/Ioff current in terms of threshold voltage.. like can we take 2Vt to be gate voltage for the Ion current..

 

[Tahmid]

Hi,
Thought this might help you:
The minimum current at the gate of the MOSFET:
Gate Current(Ig) = Gate Charge(C) * Frequency(Hz)

Hope this helps.
Tahmid.