MOSFET can be used as a?

By Balaji

Updated on: March 22nd, 2023

MOSFET can be used as a Voltage Controlled capacitor. The gate and channel are separated by a thin layer of SiO2. Therefore, they form a capacitance that varies along with gate voltage. Here, MOSFET acts as a MOS Capacitor. It is controlled by the input gate to source voltage and hence, acts like a voltage-controlled variable capacitor.

Functional Region of MOSFET

The full form of MOSFET is Metal Oxide Semiconductor Field Effect Transistor. If a MOSFET’s gate and drain are shorted, it can function as a small-signal resistor. When the Drain, Source, and bulk (body) of a MOSFET are shorted, this acts as one capacitor plate, and the Gate acts as another capacitor plate. The three main functional regions of a MOSFET are as follows:

  • Cut-off Region: The MOSFET is regarded as being in its “OFF” state when it is in the cut-off region. This means that no current passes through it when it is turned OFF.
  • Saturation Region: Saturation is the state where the MOSFET’s current flow is constant. It acts as a closed switch in this area, enabling current to flow freely.
  • Linear/Ohmic Region: Increasing the voltage across the drain and source also increases the current flowing through the MOSFET in the linear/ohmic zone.

The MOSFET is considered the basic building block and the most frequently manufactured device. It is also the most common semiconductor device in both analog and digital circuits.

Important Facts about the MOSFET

Essential characteristics of the Metal oxide semiconductor field effect transistor are given below. Knowing about these facts is mandatory to know by candidates preparing for government exams. It is one of the essential topics of physics and electronics.

  • Mosfet is a voltage-controlled device with high input impedance.
  • It has two types; P- type and N- type.
  • No input current is needed to control the load current.
  • It has three terminals, namely Drain, Source, and Gate.
  • The Gate terminal controls the flow of carriers between two terminals.
  • It is a majority carrier device.

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