Advantages, disadvantages and applications of FET over BJT

Advantages, disadvantages and application of FET over BJT

Advantages

1.       FET gas high input impedance of several mega ohms.

2.       The noise produced by a FET is less than that produced by a BJT.

3.       FETs are less effect by radiation compared to BJT.

4.       FET has no offset voltage at zero drain current and hence it forms an excellent signal chopper.

5.       FETs are voltage controlled devices.

6.       FETs have better thermal stability.

7.       In the integrated circuit form FET is simpler to fabricate and it occupies less – space.

Disadvantages

FETs have a drawback of smaller gain bandwidth product compared to BJT.

Applications

The high input impedance and low output impedance and low noise level make FET for superior of the bipolar transistor. Some of the circuit applications of FET are

1.       As a buffer amplifier: Because of high input impedance and low output impedance, a FET can act as an excellent buffer amplifier.

2.       Phase shift oscillators: The high input impedance of FET is especially valuable in phase shift oscillator to minimize the loading effect.

3.       In Voltmeters: The high input impedance of FET is useful in Voltmeters to act as an input stage.