Electronics & Software – Tips & Guide


What are the modes of operation of MOSFET

What are the modes of operation of MOSFET?

depletion mode and enhancement mode.

in depletion mode, the mosfet functions as a jfet with a more negative grid voltage compared to the source. The gate voltage can not be positive. in enhancement mode, the source-gate voltage is positive. mosfet can be used in enhancement mode or exhaustion mode.

in enhancement mode, there is no channel [connection] between the source and drain terminals. the applied source gate voltage is connected in such a polarity to establish a flow of electrons or source drain holes and increasing current

in depletion mode, the source gate voltage reduces the size of the flux channel. electrons or holes so that the current decreases.

  • flow of electrons in case of channel n
  • flow of holes in case of channel p

There are two modes of operation of the mosfet:

  • mode of enhancement
  • mode of depletion

in the channel in mode of improvement is not pre-existing and must be created by applying the appropriate grid to the source voltage in depletion mode, the channel is not pre-existing.

in the channel in enhancement mode is an induced channel, while in the depleted mode, the channel is a diffuse channel.

in enhancement mode if vgs equals zero and vds is applied, drain current (id) equals zero because there is no channel between source and drain in depletion mode if vgs is kept at zero and vds is applied, drain current (id) streams.

drain to the source saturation current (idss) in the case of the enhancement mode, it is in microamperes, while idss in the case of the exhaustion mode, in the miliampere mode.

mosfet is a semiconductor device used to switch and amplify electronic signals. if the channel consists of electrons, it is called nmos; if it consists of holes, it is called pmos.


it is also called inversion layer. Enhancement mode mosfets are common switching elements. it increases the conductivity with the increase of the oxide field which adds carriers to the channel. these devices are switched off at a zero source-gate voltage for nmos and pmos and turn on by increasing the gate voltage higher than the source voltage for nmos or lower than the source voltage for pmos.

in a mosfet in depletion mode, the device is normally lit at zero source-gate voltage. The mosfets in depletion mode are better than the enhancement mode transistors, in case of approximation of the current source, especially when no additional voltage is available. if the circuit operates as load transistors, it will allow single-voltage operation and will achieve a higher speed than possible with pure boost load devices.