Answer to No.1
a) Enhancement mode
An n-channel MOSFET transistor is Normally-OFF (enhancement mode)
if its threshold voltage, VTn, is a positive
value. You can verify this by adjusting the VT
and observing its value in the lower-right box.
- A MOSFET device is normally-OFF if the device is OFF at zero gate-source
bias (Vgs = 0).
- An n-channel MOSFET is ON if Vgs is more positive than VTn
(i.e., Vgs > VTn ).
- If VTn = 2.5 V (a positive voltage), then
the NMOS is OFF because Vgs < VTn
at Vgs = 0 V, and thus it is normally-OFF.