explain the input and output characteristics of depletion p type MOSFET
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Answer:
MOSFETs are tri-terminal, unipolar, voltage-controlled, high input impedance devices which form an integral part of vast variety of electronic circuits. These devices can be classified into two types viz., depletion-type and enhancement-type, depending on whether they possess a channel in their default state or no, respectively. Further, each of them can be either p-channel or n-channel devices as they can have their conduction current due to holes or electrons respectively. However inspite of their structural difference, all of them are seen to work on a common basic principle which is explained in detail in the article “MOSFET and its Working“. This further implies that all of them exhibit almost similar characteristic curves, but for differing voltage values.
In general, any MOSFET is seen to exhibit three operating regions viz.,
Cut-Off Region
Cut-off region is a region in which the MOSFET will be OFF as there will be no current flow through it. In this region, MOSFET behaves like an open switch and is thus used when they are required to function as electronic switches.
Ohmic or Linear Region
Ohmic or linear region is a region where in the current IDS increases with an increase in the value of VDS. When MOSFETs are made to operate in this region, they can be used as amplifiers.
Saturation Region
In saturation region, the MOSFETs have their IDS constant inspite of an increase in VDS and occurs once VDS exceeds the value of pinch-off voltage VP. Under this condition, the device will act like a closed switch through which a saturated value of IDS flows. As a result, this operating region is chosen whenever MOSFETs are required to perform switching operations