What is the difference between JFET and MOSFET?

Difference between jfet and mosfet

Lets understand about difference between JFET and MOSFET, Main difference is current control and voltage control in circuit.

First need to know what is Field Effect Transistor (FET) use and what is use of Metal-oxide semiconductor field-effect transistors (MOSFETs).

Field Effect Transistor (FET):

  • The Field Effect Transistor (FET) is a three-terminal semiconductor device that has many similarities and differences with the two-way junction transistor (BJT).
  • The main difference between BJT and FET is that BJT is a current control device, while FET is a controlled voltage device.
  • The field effect transistor is a device in which the current flow through the conductor region is controlled by an electric field. This is called Field Effect Transistor (FET).
  • The current pipeline in the device is only by the majority carriers, so it is also known as the Unipolar device.
  • FET can be classified into two types based on the construction. These are
  • Junction Field Effect Transistor (JFET)
    Metal Oxide Semiconductor Field Effect Transistor (MOSFET)
  • JFET has been classified into two types, namely
    N – Channel JFET (Electrons are the major carriers)
    P – Channel JFET (holes are the majority carriers)

Metal Oxide Semiconductor Field Effect Transistor (MOSFET)

Metal-oxide semiconductor field-effect transistors (MOSFETs) are the family of unipolar transistors. A distinctive feature of the MOSFET is the construction of the gate. The gate is completely isolated from the channel. The tension applied to the gate will cause electrostatic charging. It is not allowed to run the current in the gate area of the device. The gate is simply an area of the metal-covered device.

The other names for MOSFET are Isolated Gate Field Effect Transistor (IGFET), Silicon Transistor Metal Oxide (MOST) MOSFET are classified into two types namely

  • Depletion Mode MOSFET
  • Enhancement Mode MOSFET


By comparing with JFET, MOSFETs are easier to fabricate (jfet vs mosfet).

  • JFETs are only run in exhaustion mode. The type of MOSFET exhaustion can be used in both exhaustion mode and enhancement mode.
  • The output characteristics of JFET are more plane than the MOSFET. because the leakage resistance in JFET (1 MΩ) is higher than the MOSFET (50kΩ)
  • The drain current of the JFET gate is of the order 10-9A. For MOSFET, the drain current will be 10-12A.
  • The input resistance of the JFET is in the range of 108Ω. For MOSFET, the input resistance will be between 1010 and 1015Ω.
  • Because of their advantages, MOSFETs are widely used in VLSI circuits than JFETs. Since MOSFET is susceptible to overloading voltages, special attention must be paid to the installation.
  • MOSFET has zero offset voltage. Source and leakage terminals can be changed (so called symmetric device). Because of these two features, MOSFET is widely used in switching analog signals.

In the JFET, the transverse electric field along the PN PN reversible junction controls the conductivity of the channel. In the MOSFET, the transverse electric field induced over an insulating layer deposited on the semiconductor material controls the conductivity of the channel.

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