body source voltage of pmos

[jason_class]

Hello Everyone

I would like to check with you all if SMALL SIGNAL Vbs for pmos is always zero is the bulk and source is at Vdd?
Kindly enlighten
Thank you all

best regards
Jason

 

[richloo]

Not necessary at Vdd, it might be at <Vdd. As long as the bulk and the source are connected together.

 

[jason_class]

Thank you Rich. It is good to see your helpful comment.

 

[sabu]

ya it is obvious i thnk
thanking u

 

[Karthikeya]

hi richloo
i am not thoroughly convinced with your answer. What if source is at Vdd and bulk and some constant voltage (say 0.1*Vdd). In that case the ac equivalent has source and bulk at zero but they not both at Vdd.

 

[richloo]

Hi Karthikeya,

u r correct too. What i m trying to say is that as long as the bulk and source of the PMOS is connected together, vbs is always zero.