Hello Friends. In this article, I will explain to you in detail about the field-effect transistor and its structure, configuration, and its construction. FET is widely used in an electronic circuits. In our daily life, FET circuit design are used. There are different types of FET and all of them will be explained in this article. So, without wasting anytime lets start.
What is Field Effect Transistor?
Definition
A field-effect transistor (FET) has a three-terminal unipolar device in which conduction takes place with the help of an applied electric field.
Construction of FET
There are three main terminals of Field Effect Transistor and they are explained as follows:
Source
It is the electrode of the transistor. It acts as a source when the charge carriers are entered towards the channel. It is known as source for providing charge carriers.
Drain
Drain (electrode of the transistor) is the point where the majority charge carrier leaves the channel. The drain to source voltage is chosen by VDS.
Gate
The gate is known for controlling the conductivity if the channel. On apply the voltageon can easily control ID.
Working Principle of FET
Schematic Symbol of FET
Following diagram represents the schematic symbol of Field Effect Transistor:
Here in this diagram vertical line represents the channel from which the source and the drain are connected. The third terminal gate is connected at the center of the vertical line. In the first diagram (n-type channel), the gate and the channel form the PN junction the gate, the gate arrow is inwards and in the p-channel, the gate arrow is outward.
Structure of Field Effect Transistor
The main basis of all the Field Effect Transistors is semiconductors. The semiconductor is used for either the P-type channel or the N-type. In the case of designing the N-channel then N-type semiconductors are used and P-type semiconductors will be in between the N-type semiconductor.
Working of FET
Let’s discuss the working principle of the Field Effect transistor as we have already discussed its main components of it.
- The Voltage (VDS) is applied between the source and drain and the voltage across the gate is zero
- The PN junction forms a depletion region at the side of bars
- Flow of electron take place from the source towards the drain by the channel in between the depletion region
- Current of flows the bar
- Voltage (VGS) in reverse direction applied between the gate and the source causes an increase in the width of the depletion region
- There is also a reduction in the width of conducting channel
- The resistance of the f n-bar increases with a decrease in the width of conducting channel
- On the other hand, the current form source and drain are reduced
- If the voltage the (in the reverse direction) across is reduced reduce then the width of the depletion region also decreases., With this, the width of the conduction channel and current from source to drain also increases
- Current from the source toward the drain is controlled by the application of potential on the gate. Due, to this reason the transistor is named as Field Effect Transistor
Characteristics of Field Effect Transistor
The output characteristics field-effect transistor is explained by a graph that shows a curve between the drain current and the drain-source voltage of FET with the gate-source at constant. The following graph represents the working of FET:
Advantages of FET
There are numerous advantages of the Field-effect transistor as it is a voltage-controlled current (constant) device. By keeping the current constant and variating the input voltage, the output current can be controlled easily. The following are some important advantages of FET:
- The negative temperature coefficient of resistance is present in FET. Due to these characteristics, it can overcome the risk of the thermal runaway.
- The FET has high power gain and it avoids the need of using the driver stages.
- Such types of transistors are smaller in size, highly efficient, and have a longer life.
- Field Effect Transistor has high impedance and this characteristic permit high isolation among the output and input circuits.
Classification of Field Effect Transistor
A Field Effect Transistor is classified into different types. The below-mentioned table elaborates the types of FET:
Conclusion
Field Effect Transistor helps in different fields of electronics. Due to its characteristic of high impedance and a voltage device, it is used in many active devices. Hope you learn new things about FET and understand its working principle. Thanks for reading.