Why mosfet

When we apply positive gate voltage the holes present under the oxide layer with a repulsive force and holes are pushed downward with the substrate. The depletion region populated by the bound negative charges which are associated with the acceptor atoms. The electrons reach the channel is formed. Now, if a voltage is applied between the drain and source, the current flows freely between the source and drain and the gate voltage controls the electrons in the channel.

If we apply negative voltage, a hole channel will be formed under the oxide layer. When we apply negative gate voltage, the electrons present beneath the oxide layer experience repulsive force and they are pushed downward in to the substrate, the depletion region is populated by the bound positive charges which are associated with the donor atoms.

When we apply the positive gate voltage the holes present beneath the oxide layer experience repulsive force and the holes are pushed downwards in to the bound negative charges which are associated with the acceptor atoms. More basic articles available in the learning corner.

This is very useful basic but important information for learners. Some gif animations or java applets could have enhanced learning experience. For instance, showing characteristics with increasing voltage at pinch off position, recombinations of electron hole pairs, etc. Save my name, email, and website in this browser for the next time I comment.

VI characteristics:. The small amount of voltage at the gate terminal will control the current flow through the channel. The channel formed between the drain and the source will act as a good conductor with zero bias voltage at the gate terminal. The channel width and drain current will increase if the positive voltage is applied to the gate whereas they will get decreased when we apply a negative voltage to the gate.

The channel width and drain current will increase when the bias voltage increases. But if the applied bias voltage is zero or negative the transistor will remain in the OFF state itself. VI Characteristics:. The VI characteristics are partitioned into three different regions, namely ohmic, saturation, and cut-off regions. When the bias voltage is applied, the MOSFET slowly moves towards conduction mode, and the slow increase in conductivity takes place in the ohmic region.

Actually when V DS is increased, the drain current I D should increase, but due to the applied V GS , the drain current is controlled at certain level. Hence the gate current controls the output drain current. The below transfer characteristic curve is drawn for drain current versus gate to source voltage. So far, we have discussed various electronic components and their types along with their construction and working.

All of these components have various uses in the electronics field. Previous Page. Next Page. Previous Page Print Page. Save Close. Dashboard Logout. The image below shows a comparison of the drain current with no series gate resistor yellow trace and with W blue trace , limiting the gate current to mA.

The magenta signal is the drive signal seen before the series resistor. You can see the effect of the gate current limitation on the rise and fall times as well as the delay.