Value of Vout in PMOS Inverter?

[jean28]

Hey guys. I am simply trying to derive the equation for Vout in a PMOS inverter (attached). I know that in an NMOS inverter (which has the resistor in top of the transistor instead of the bottom) the equation for Vout is:

Vdd - id*rd.

But how does the resistor being in the bottom change this behavior? Is it now Vcc - ground? (which would equal Vcc).

Thanks.

 

[jean28]

It could also be Vout = id * Rd.

 

[NascentOxygen]

It could also be Vout = id * Rd.

If by Rd you mean that external resistor, then that looks right for output logic HIGH.