The MOSFET threshold voltage is the topic we discussing in this article, threshold voltage is an important electrical characteristic of field-effect transistor devices.
At MOSFET threshold voltage is also called the gate to source voltage, we know there are different types of MOSFETs are available but the most important division will be in terms of its polarity basis that is N-channel and P-channel MOSFETs. In this article, we include threshold voltage values of these MOSFET types and an equation for the threshold voltage at MOSFETs.
MOSFET threshold voltage?
The MOSFET threshold voltage is the gate voltage or gate to source voltage for which the device gets trigger started.
The threshold voltage will be indicated as VT or VTH.
MOSFET threshold voltage equation
b = kT/q 1n (NA/Ni)
NA = doping concentration
Ni = intrinsic concentration
k = Boltzmann’s constant
εSi = permittivity of silicon
Cox = gate oxide capacitance
Cox = εox/ tox
Vfb = ϕms – Qfc/ Cox
Qfc = fixed charges due to silicon oxides
Φms = difference between silicon subtract and gate material
N channel MOSFET threshold voltage
The threshold voltage of n-channel MOSFET is a +VE value, which is between 0.7 to 1.0v.
P channel MOSFET threshold voltage
The threshold voltage at p-channel MOSFET is a –VE value, which is between -2.0 to -4.0v.
The threshold voltage of the MOSFET is dependent on the doping density of the MOSFET device.
- The substrate doping vs threshold voltage graph shows the difference in threshold voltage of n-channel and P-channel MOSFETs.
- The n-channel MOSFET increases towards +VE voltage values and the p-channel MOSFET decreases to –VE voltage value, due to the doping density.
2n7000 MOSFET threshold voltage
The 2n7000 is an n-channel MOSFET, they have a 3v threshold voltage.