INVERSION LAYER:

In Enhance mode operation, the Drain to Source Channel does NOT have any charges and no conduction along Channel.

When a Positive Voltage is applied to the GATE, this attracts the charges [ Electrons ] Under the SiO2 layer from Drain and Source and, hence conduction starts as gate Voltage increases.

Therefore, from No Charges in the Channel to Charges in the Channel is INVERSION of Charge Layer is created.


THRESHOLD VOLTAGE:

the value of Vgs at which the inversion layer is formed is called threshold voltage.


Enhancement mosfet working:

  • when Vgs has increased the minority charge carriers in p-substrate get attracted towards the opposite side of Gate. Hence the channel is formed.
  • Now when the Vds is applied then the current through the channel is started.
  • As voltage is increased between the drain and source the channel becomes like below

  • as the Vds increases at some point the channel at the drain side becomes less(negligible) that voltage is called pinch of voltage or it is called Vgs(sat).


  • But rather the channel is closed at drain side the current from the drain to source flows constantly.


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