What does MOSFET stand for?
Metal-Oxide-Semiconductor Field-Effect Transistor
What are the three terminals of a MOSFET?
Gate (G), Drain (D), and Source (S).
What are the two main types of MOSFETs?
n-channel MOSFET (NMOS) – conducts when a positive voltage is applied to the gate.
p-channel MOSFET (PMOS) – conducts when a negative voltage is applied to the gate
What are the two operation modes of a MOSFET?
Enhancement mode – normally off; requires gate voltage to turn on
Depletion mode – normally on; requires gate voltage to turn off.
How does a MOSFET control current?
By applying a voltage to the gate terminal, which creates an electric field that modulates the conductivity of the channel between drain and source.
Which MOSFET terminal controls the channel conductivity?
The Gate terminal.
What is the difference between a depletion-mode and enhancement-mode MOSFET?
Enhancement-mode: Normally off; gate voltage is required to create a channel.
Depletion-mode: Normally on; gate voltage is required to deplete the channel and turn off.
What is the threshold voltage (V_th) in a MOSFET?
The minimum gate-to-source voltage (V_GS) needed to create a conducting channel between drain and source.
What is the main advantage of MOSFETs over BJTs?
High input impedance and very low gate current, making them easier to drive and more efficient in switching applications.
What is the typical symbol difference between NMOS and PMOS?
NMOS: Arrow on the source points out.
PMOS: Arrow on the source points in.
Name a common application of MOSFETs.
Switching power supplies, motor drivers, amplifiers, digital logic circuits.
What is the “on-resistance” (R_DS(on)) of a MOSFET?
The resistance between drain and source when the MOSFET is fully on. Lower R_DS(on) means less power loss.
How do MOSFETs behave in saturation and triode regions?
Triode/Linear region: Acts like a variable resistor; used for amplification.
Saturation region: Acts like a current source; used for switching.
What is MOSFET transconductance (gm) ?
The rate of change of drain current with respect to gate voltage.
What is the difference between enhancement-mode NMOS and PMOS in terms of polarity?
NMOS: V_GS > V_th (positive) → conducts
PMOS: V_SG > |V_th| (negative gate voltage relative to source) → conducts
