Answer to No.2
b) Vgs < VTp
A PMOS is turned ON if Vgs < VTp. That is if the Gate-Source bias,
Vgs, is more negative than the Threshold voltage, VTp. Now
let us verify it:
- apply logic 0 (blue) to Vin. The PMOS
is closed (ON).
- Vg = Vin <= VIL = 1.0 V. Vs = Vcc = 5.0
V. Therefore, Vgs = Vg - Vs <= - 4.0
- VTp = - 2.5 V (see lower-right hand box after moving VT
a little in the left hand side of applet.)
- So we see that Vgs < VTp when the PMOS is ON.
- This is true for a range of Vin, Vcc, and VTp.