Depletion MOSFET

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Depletion mode of NMOS and PMOS

  1. Depletion N MOSFET:

Fig: NMOSFET - depeletion

  1. VGS =  0 volts VDS > 0

Though the VGS is zero volts but due to external supply at drain and the presence of channel the electric field from drain causes electrons from source to travel from source to drain there by causing drain current.

  1. VGS  > 0

The channel depth increases due to applied supply at the gate and the channel enhances.

  1. VGS < 0 

The channel starts decreasing as gate potential is being reduced this leads to zero current. Thus the depletion of the channel occurs; this is named as “Depletion N MOSFET”.

The voltage at which the device starts depleting its channel is called threshold voltage.






  1. Depletion P MOSFET:

Fig: PMOSFET –depletion


  1. VGS =  0 volts VDS < 0

Though the VGS is zero volts but due to external supply at drain and the presence of channel the electric field from source causes electrons from drain to travel from drain to source thereby causing drain current.

  1. VGS  < 0

The channel depth increases due to applied supply at the gate and the channel enhances.

  1. VGS > 0 

The channel starts decreasing as gate potential is being increased this leads to zero current. Thus the depletion of the channel occurs this is named as “Depletion N MOSFET”.

The voltage at which the device starts depleting its channel is called threshold voltage.


  • Transfer characteristics of E-PMOSFET, E- NMOSFET, D- PMOSFET, D-NMOSFET:

Fig: Transfer characteristics of E-PMOSFET, E- NMOSFET, D- PMOSFET, D-NMOSFET

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