Vds, Vgs, Vdsat of PMOS?

[yonzzan]

vds vgs

Vds, Vgs, Vdsat of PMOS are negative. If I convert it into positive, do I have to subtract them from 1.8V( PMOS2V) or can I just use the absolute number of them?

 

[chemaphy]

vdsat negative

Hello,

You will not have to subtract all of them by 1.8V, but you will have to be careful with the conditions for different operation mode of the PMOS.

For triode region:
Vds > Vgs - |Vt| where Vds and Vgs are +ve

For saturation region:
Vds < Vgs - |Vt| where Vds and Vgs are +ve

Regards,
chemaphy

 

[shockie]

vds,vgs,

little bit confued here.
For triode region.
|Vds|<|Vgs|-|Vt|

For saturation region.
|Vds|>|Vgs|-|Vt|.

 

[analog_guru]

pmos vt versus vds

You are right shockie in all both of your assumptions. i.e., subtract the abs. value of those from Vdd.