A transistor is a semiconductor device used to amplify or switch electronic signals or electrical power. It has three terminals and made by a semiconductor material if a voltage or current is applied to one pair of transistor’s terminals control the current through other pair of terminal we can see many transistors in integrated circuits it is the fundamental building block of modern electronic devices transistors are used for amplification purpose because the controlled output power is higher than the controlled input power. It will be helpful for amplification. Most of the transistors are made from semiconductor materials like silicon or germanium. Transistor has revolutionized the electronic field and it paved a way for smaller efficient and cheaper electronic devices. Majority of the transistors are seen in integrated circuits logic gates consist of twenty transistors were as a microprocessor consists of three billion transistors. Mechatronics circuit using transistors have replaced the electromechanical devices in controlling appliances and machinery. It is easier and cheaper to use a microcontroller and write a program instead of designing an equivalent mechanical system

A transistor is a semiconductor device that can conduct and insulate. A transistor can act as a switch or an amplifier it converts audio waves into electronic waves transistor have very long life smaller in size can operate on lower voltage supplies for greater safety and no need for filament current A transistor is a three-terminal device Base this is responsible for activating the transistor Collector this is the positive lead Emitter this is the negative lead


There are two types of transistor BJT bipolar junction transistor and FET field effect transistor

Bipolar junction transistor

BJT are transistors which are built for three regions base, collector & emitter. A small current entering the base will cause a large current flow from emitter to the collector region. BJT transistors come in two types NPN and PNP. NPN transistor in which majority charge carrier is electrons. Electrons flowing from emitter to collector forms the base of the majority of current flow through the transistor and holes are minority charge carriers. In PNP transistors the holes are majority charge carrier and electrons are the minority.



FET IS made up of three regions gate, source and drains FET are voltage controlled device a voltage placed at the gate controls the current flow from source to the drain this FET has high input impedance and it will cause them to have a very small amount of current. So FET only draws very little current from the circuit and thus they won’t disturb the original circuit power elements which they are connected to the main drawback of FET is they won’t provide much amplification as BJT image


This transistor is a combination of a transistor and a Schottky diode which prevents the transistor from saturation by diverting the extreme input current. in a saturated transistor, the stored charges will create problems while the transistor needs to be switched from on to off all the charges must be removed in order to switch off the transistor so removing the charges will cause time delay this can be eliminated by the help of Schottky transistor



MOSFET is a type of field effect transistor it has insulated gates whose voltage determines the conductivity of the device this ability to change conductivity with the amount of applied voltage can be used for amplifying or switching signals the main advantage of MOSFET is that it doesn’t need an input current to control the load current compared to BJT



The junction field effect transistor is a simple type field effect transistor it can be used as electronically controlled switches amplifiers or voltage controlled resistors it has a semiconductor material in place of PN junction forming a channel of either N-type or P-type. There are two basic configurations for JFET the p channel JFET and n-channel JFET if the channel is doped with impurities meaning that the flow of current through the channel is negative in the form of electrons. JFET are extremely voltage controlled they do not need biasing current. Electric channel flows through a semiconductor channel between a source and drain terminals by applying a reverse bias voltage to gate terminal JFET is usually on when there is no potential difference between source and drain


APPLICATIONS • It is used to regulate current or to amplify an input signal • To switch electronic signals • It is very small due to its size it can be used in many circuits • It is biased to operate in saturation or cutoff region for switching applications • It used in amplifier devices • Every cellphone uses a transistor amplifier • Used in power regulators & controllers • It is used to build integrated circuits • It is used in touch and light sensing device • Transistors are used in satellites and aerospace application