what is the input common range of the folded-cascoded OTA?

[yeziwong]

what is the input common range of the folded-cascoded OTA?

 

[dineshbabumm]

Vdd - (2 * Vov + Vt) to Vov!

 

[yeziwong]

Re: what is the input common range of the folded-cascoded OT

i think the upper limit is vdd-(2vov+vgs)=vdd-(3vov+vt)
but i am not sure what the lower limit is.
please tell me

 

[dineshbabumm]

Yeah sorry i made a mistake! Upper limit specified by you is correct!

Lower limit is the over drive voltage needed by transistor M11(and M12)!

 

[yeziwong]

Re: what is the input common range of the folded-cascoded OT

hi dineshbabumm
i think the lower limit should be vov-abs(vthp,input)

 

[dineshbabumm]

Hi yeziwong,

I think it is Vov alone! Because lower limit specifies how low your input voltage can go without affecting the other transistors from saturation region.. So to make the transistor M11 in saturation we need Vov constantly and hence our input signal can go until Vov..

Also i dono wats Vthp,input! I feel it will be Vov alone! Sorry if i am wrong!