the definition of sub-threshold area

[sunjiao3]

Hi, friends. I know that when Vgs get very close to Vth, the operation area is called sub-threshold area. But, is there a clear definition, a water shed on it? I mean, judge by the value of Vth and Vgs. In the *.lis file produced by hspice, the states are only divided into saturati, cutoff and linear. So, how can I decide whether it is subtheshold by the value of Vgs and Vth? Thank you all in advance.

 

[windarray]

hi friends,
sub-threshold area is also called weak invert area,existing when vgs<vth,more generally,the area can be diveded into strong invert,moderate and weak invert.

 

[samuel]

it can depent on your ID.

 

[pra]

when vgs is just below the Vth then we call it as subthreshold or weak inversion region..
roughly vgs shud be in between vth and vth-5vt where vt=26mv

 

[Sergiu_Q]

If you want to calculate the threshold voltage this will help you : **broken link removed** , Chapter 7: MOS , 7.4. Threshold voltage