I understand that in an n channel MOSFET as Vgs increases, electrons are attracted towards the gate forming an n channel. These electrons are responsible for the conduction of the MOSFET. As Vds crosses saturation voltage a pinch-off occurs. This pinch-off results in channel tapering and the n channel effectively reduces. My question is if tapering occurs, shouldn't the available charge carriers in the channel reduces thus reducing current flow?
Electronic – MOSFET pinchoff reduce current
analogmosfetpower electronics
Best Answer
As the channel current increases, so does the drop across it (the channel is like a resistance), and as a result the drain voltage rises above source voltage. This does start to constrict the channel but as the channel gets pinched the drop gets limited as well and so a form of equilibrium is reached which limits the maximum current the channel can carry.