Quick Answer: Why Is FET Better Than BJT?

What are the types of FET?

There are two main types of field effect transistor, the Junction Field Effect Transistor or JFET and the Insulated-gate Field Effect Transistor or IGFET), which is more commonly known as the standard Metal Oxide Semiconductor Field Effect Transistor or MOSFET for short..

Why is it called field effect transistor?

FETs are special type of transistors which are controlled by the voltage applied across the input terminal called the ‘Gate’. The electric field produced due to this gate voltage controls the operation of the FET . Thus as they are dependent on the ‘field’ applied across their input ,they are called so.

Why MOS is better than BJT?

MOSFET is a lot faster than BJT since in a MOSFET only majority carriers constitute the current. The device switches lot faster than BJT and hence is used in switching power supply SMPS. … Because collector current changes due to temperature changes, current gain changes,base emitter voltage changes.

What is the main difference between BJT and FET?

BJTS and FETs can be used as switches and amplifiers in electrical and electronics circuits. The major difference between BJT and FET is that, in a field effect transistor only majority charge carries flows, whereas in BJT both majority and minority charge carriers flows.

Why BJT is more noisy than FET?

BJT’s are noisier than FET’s. A BJT is having two pn junctions whereas an FET is having only one pn junction. Hence charge carriers will have to cross more depletion regions in BJT and hence the possibility of addition of thermal noise and minority charge carriers is much higher.

What is the symbol of FET?

Junction FETs or JFETs were the first type of FET and these have a distinctive symbol showing the diode junction. Insulated gate FETs, including MOSFETs have circuit symbols that indicate the insulation on the gate. Obviously dual gate FETs have two gates and both need to be incorporated into the circuit symbol.

Why input characteristics of FET is not drawn?

In the case of FET of any kind, the current drawn by the gate is extremely, negligibly small, small enough to interfere with the working of the connected circuits. The plot of the gate current vs the voltage shows almost nil change in the current, except in the case of an FET gate junction which is forward biased.

What is BJT configuration?

The BJT transistors have mainly three types of configurations. They are common-emitter, common-base and common-collector configurations. Among all these three configurations common-emitter configuration is mostly used type. These three have different characteristics corresponding to both input and output signals.

Why FET is preferred over BJT?

FETs are voltage-sensitive devices with high input impedance (on the order of 107 to 1012 Ω). Since this input impedance is considerably higher than that of BJTs, FETs are preferred over BJTs for use as the input stage to a multistage amplifier. … Power FETs can dissipate high power and can switch large currents.

What are the disadvantages of FET?

Disadvantages of FETsFETs have a poor frequency response due to its high input capacitance.FETs have a very poor linearity, and generally they are less linear than Bipolar Juntion Transistor.FETs can be damaged due to the static electricity.

What is the principle of FET?

JFET Working Principle. The field-effect transistor (FET) relies on an electric field to control the shape and hence the conductivity of a channel of one type of charge carrier in a semiconductor material. Let’s move on to JFET as it should get more emphasize. a junction is always reverse biased in normal operation.

What are the applications of FET?

FETs are widely used as input amplifiers in oscilloscopes, electronic voltmeters and other measuring and testing equipment because of their high input impedance. As a FET chip occupies very small space as compared to BJT chip, FETs are widely used in ICs.