What is the difference between a fet and a bipolar transistor

Due to this, the BJT consumes more power which is wasted in the form of heat. Therefore, BJT gets hot very quickly and the temperature also affects its operation. This is why its temperature must be regulated using large heatsinks in order to work normally. BJT is temperature-dependent. The current flow in FET is due to the flow of only one type of charge carrier i. Therefore, FET is also known as a unipolar transistor.

There are two types of FET transistors i. These transistors are also used for switching as well as amplification in electronic circuits. Based on its construction, FET is available in two types i. The channel refers to the path for the flow of current from source to drain terminal. The carriers enter the channel through the source and leave out at the drain. There are no PN junctions between the source and drain. The Gate region is made from alternate material as compared to the channel.

The Gate is reversed biased in order to form a depletion region so that the channel between drain and source is formed. Which leads to the current flow. Increasing the reverse bias voltage at the gate increases the depletion region which results in increasing the current flow. Therefore, the voltage at the gate is used to control the output current. Therefore FET is also known as a voltage-controlled current device.

There is very little difference between the source and drain terminal. The drain terminal should be connected to a more positive voltage as compared to the source terminal. Therefore, they can be swapped i. The majority charge carrier is identified by the type of FET being used. FET has 3 regions i. Active, saturated and cutoff region. The FET acts as an amplifier in the active region while it acts as a switch in the saturated and cutoff regions.

Since the input gate is reversed biased, the input impedance of FET is very high in the range of M ohm which is why there is no current flow at the gate terminal. And the output impedance is low. Since the FET utilize only one type of charge carrier either electrons or holes, the recovery time is very fast. These transistors have the property of both conduction as well as insulation. These transistors are found everywhere as the basic components of electronic systems.

It comes under various sizes and with multiple shapes. The main criteria of these transistors is to control the flow of current that passes through one channel by making the variations in the intensity of the currents that are very smaller which flows through the second channel. On the other hand, collector C section is moderately doped, its main function is to collect charge carriers.

Bipolar junction transistors are mainly used in switching and amplification. The various applications of bipolar junction transistors include:. Bipolar junction transistors are classified into two types based on their construction. They include:. They are commonly referred to as unipolar transistors because they involve single-carrier-type operation that is, they use electrons or holes as charge carriers in their operation, but not both.

FET is commonly used for weak-signal amplification for example amplifying wireless signals. The device can amplify analog or digital signals. The drain is the terminal through which carriers leave the channel. The gate is the terminal that modulates the channel conductivity by application of voltage to this terminal. FET is referred as unipolar transistor. In FET input voltage controls the output current, here input current is usually negligible.