The Types of Transistor and its Application in Daily Life

Types of Transistor Overview

A semiconductor device known as a transistor is commonly utilized to switch or amplify electronic signals within an electric circuit. Transistors are primarily categorized into two types: field-effect transistors (FETs) and bipolar transistors (also called bipolar junction transistors, BJTs). Additionally, there are numerous other types of transistor that are classified based on their characteristics, advantages, and disadvantages.

Field-effect transistors are unipolar devices that lack a PN junction in their current-carrying path. They are generally divided into two categories: N-channel and P-channel transistors. On the other hand, bipolar transistors employ both holes and electrons as charge carriers and are classified as NPN and PNP transistors.

Lastly, another type of transistor is insulated-gate bipolar transistors, which contain both a voltage-driven MOSFET and a high-current transistor.

What is a Transistor?

A transistor is a sort of electrical device made up of p-type and n-type semiconductors. The transistor is a configuration in which a semiconductor is placed between two semiconductors of the same sort.

1. A transistor can also be described as the joining of two diodes at the same time.
2. A transistor is a component that regulates current or voltage flow and acts as a button or gate for electrical impulses.
3. It consists of three terminals: transmitter, base, and collection.
4. Transistors have had a major effect on the revolution in the electronic sector.
5. It can do both signal amplification and signal rectification.

Working Principle

A transistor depends on the idea that it enables you to regulate the flow of current through one route by changing the strength of the tiniest quantity of current going through a second path.

Types of Transistor

There are many Types of Transistor that can be classified on the basis of their application. Some of these are – 

1. Bipolar Junction Transistor
2. Diffusion Transistor
3. Avalanche Transistor
4. Schottky Transistor
5. Darlington Transistor
6. Heterojunction Bipolar Transistor
7. Field Effect Transistor
8. Junction FET Transistor
9. Dual Gate MOSFET
10. Multiple-Emitter Transistor 

1.Bipolar Junction Transistor (BJT)

Bipolar Junction Transistors are those kinds of transistors that are made up of three regions: the base, collector, and emitter. Bipolar junction transistors, unlike FET transistors, are current-controlled electronics.

1. A little current flowing from the emitter to the collector area of the transistor causes a significantly larger current to flow from the base to the emitter.
2. Bipolar junction transistors are classified into two types: NPN and PNP.

• NPN Transistor: There are two p-type semiconductor materials used in these Types of Transistor. These elements are separated by a thin n-type semiconductor layer. The bulk of charge carriers in these transistors are holes, with electrons making up the minority.

1. In this transistor, current travels from the emitter terminal to the collector terminal.
2. The transistor will turn on when the base terminal is pulled to LOW in contrast to the emitter terminal.

• PNP Transistor: A PNP transistor is made up of two n-type semiconductor layers divided by a thin p-type semiconductor layer. Most charge carriers in an NPN transistor are electrons, with holes accounting for the remainder.

1. Electrons flowing from the emitter terminal to the collector terminal create the current flow within the transistor's base terminal.
2. A low current supply at the base terminal of a transistor can result in a significant amount of current flowing from the emitter to the collector.
3. Because electron mobility is greater than hole mobility in NPN transistors, they are presently the most widely used BJTs.

2. Field-Effect Transistors (FETs)

Field-Effect Transistors are those Types of Transistor that are made up of three regions: the gate, source, and drain. FETs are distinct from bipolar transistors in that they are voltage-controlled bipolar transistors. The current flow from the source to the drain is controlled by the voltage given to the transistor's gate.

1. Field-Effect transistors have extremely high input impedances that range from a few mega ohms (M) to exceedingly high values.
2. Because of their high input impedance, these transistors only receive a small quantity of current. (According to Ohm's Law, the current is influenced negatively by the resistance of the circuit.)
3. If the impedance is large, the current is very low.
4. Therefore, FETs draw very little current from a circuit's power source.
5. FETs can be further classified as JFETs and MOSFETs.

• Junction Field-Effect Transistor (JFET): FET transistors of this sort are used in resistors, amplifiers, switches, and other applications. This device is voltage-controlled and does not require any current biasing. The voltage applied between the gate and source terminals of the JFET transistor controls the current passage between the source and drain.

1. The Junction Field Effect Transistor (JFET) does not have PN-junctions and instead uses a narrow piece of high resistive semiconductor material to produce a Channel of either N-type or P-type silicon with two ohmic electrical connections at either end.
2. It is commonly known as the Drain and Source.
3. A junction field-effect transistor can be configured in two ways: N-channel and P-channel.

• Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET): The most common type of transistor is the MOSFET. It incorporates the terminal of the metal gate, as the name suggests. The source, drain, gate, and substrate, or body, are the four components of this transistor.

1. MOSFETs have a higher input (i/p) impedance and a lower output (o/p) impedance than BJTs and JFETs.
2. MOSFETs are mostly used in low-power circuitry, such as chips.
3. These transistors are classified into two types: depletion and enhancement.
4. These kinds are further classified as P-channel and N-channel.

Other Types of Transistor

The table below shows the other Types of Transistor with descriptions:

Types of Transistor: Application 

Transistors have a wide range of applications in electronics and other industries. Here are some common applications of transistors:

1. Amplifiers:Transistors are commonly used as amplifiers in audio systems, televisions, radios, and other electronic devices. They can amplify a weak signal and provide a stronger output signal.
2. Switches:Transistors can also be used as switches in electronic circuits. They can turn a device on or off or control the flow of current in a circuit.
3. Oscillators: Transistors can be used to generate oscillations in electronic circuits. They can produce a signal at a specific frequency, which is useful in applications such as radio communications.
4. Power supplies:Transistors can be used in power supply circuits to regulate voltage or current. They can also be used to switch between different power sources.
5. Digital circuits: Transistors are used extensively in digital circuits, such as microprocessors and memory devices. They can store and process information in binary form, which is the basis of digital electronics.
6. Lighting:Transistors can be used to control the brightness of LED lights. They can also be used in dimmer switches to adjust the brightness of incandescent lights.
7. Motor control:Transistors can be used to control the speed of motors in industrial equipment, such as pumps and fans. They can also be used in robotics and other automated systems.
8. Solar cells:Transistors can be used in solar cells to convert sunlight into electricity. They can regulate the flow of current and maximize the efficiency of the solar cell.

Overall, transistors are essential components in modern electronics and have revolutionized the way we use and interact with technology.

Things to Remember

1. A transistor is a type of electronic device which is formed by p-type and n-type semiconductors.
2. It controls the passage of current or voltage and serves as a button or gate for electronic signals.
3. Bipolar Junction Transistors are made up of three regions: the base, collector, and emitter.
   1. In PNP transistors, two p-type semiconductor materials are separated by a thin n-type semiconductor layer.
   2. In NPN transistors, two n-type semiconductor materials are separated by a thin p-type semiconductor layer.
4. Field-Effect Transistors are those Types of Transistor that are made up of three regions: the gate, source, and drain.
   1. JFETs are used in resistors, amplifiers, switches, and other applications. 
   2. MOSFET is the most used transistor. The source, drain, gate, and substrate, or body, are the four terminals of this transistor.

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Types of Transistor: Sample Questions

What is a bipolar junction transistor (BJT) and how does it work?

Answer: A bipolar junction transistor (BJT) is a type of transistor that consists of two pn-junctions, namely the emitter-base junction and the base-collector junction. It operates by controlling the flow of current between the collector and emitter terminals using a small current at the base terminal. When a small current is applied at the base terminal, it causes a large current to flow between the collector and emitter terminals, thereby amplifying the signal.

How does a field-effect transistor (FET) differ from a BJT?

Answer:A field-effect transistor (FET) differs from a BJT in that it controls the flow of current through a semiconductor channel using an electric field rather than a current. FETs have three terminals: source, gate, and drain. The gate is separated from the channel by a thin oxide layer, and the electric field generated by the gate controls the flow of current between the source and drain.

What is an insulated-gate bipolar transistor (IGBT) and how does it differ from a MOSFET?

Answer:An insulated-gate bipolar transistor (IGBT) is a type of transistor that combines the high input impedance of a MOSFET with the low on-state resistance of a bipolar junction transistor (BJT). The IGBT has a pn-junction between the emitter and collector, which is controlled by a MOSFET-like gate structure. The IGBT is used in power electronics applications due to its high voltage and current handling capabilities. The main difference between an IGBT and a MOSFET is that the former can handle higher currents but has higher switching losses.

What is a Darlington transistor, and how does it work?

Answer:A Darlington transistor is a type of BJT configuration that consists of two BJTs connected in a common-emitter configuration. It is used to achieve high current amplification with low input current. The output current of the first BJT is amplified by the second BJT, resulting in a much higher current gain than that of a single BJT.

What is a phototransistor, and how does it work?

Answer: A phototransistor is a type of transistor that is sensitive to light. It works by converting light into an electrical signal. When light strikes the base region of the phototransistor, it generates an electron-hole pair, which in turn causes a current to flow between the emitter and collector terminals. The amount of current flowing through the phototransistor is proportional to the amount of light striking the base region. Phototransistors are used in light detection applications.