Types of Transistor

What is the types of transistor ?There are two main types of transistor.

1-Bipolar Junction transistor (BJT) 2-Field Effect Transistor(FET)

Transistor Types Tree

types of transistor tree

Bipolar Junction Transistor (BJT)

Bipolar junction transistor have three terminals which is emitter ,base and collector. By control the flow of current between base and emitter we can control the current flowing between emitter and collector.BJT have two types.

P-N-P Transistor

In this type of BJT one n-type material is placed in between the two p-type materials.PNP transistor consist of 2 crystal diode which are connected in series. The transistor right side are known as collector-base diode and left side are known as emitter-base diode.

pnp transistor

N-P-N transistor

In this type of BJT one p-type material are placed in between the two n0type materials. This type of transistor are used to amplify the weak signals in electronic circuit. In his type of transistor electron move from emitter to collector as a result current flow from emitter to collector

npn transistor

Transistor configuration

Transistor have three type of configuration

Common Base Configuration (CB)

In this types of configuration the base terminal are common between the input and output terminals.

common base configuration

Common Collector Configuration

In this type of configuration the collecor are common between the inout and output terminals.

common collector config

Common Emiter configuration

In this type of configuration the emitter are common between the input and output terminals.

common emitter config

Field Effect Transistor(FET)

The FET is the types of transistor which have three terminals Source ,Gate and Drain. In this type of transistor the current between source and drain can control by the gate voltage.FET is unipolar transistor in which only majority carrier is responsible for the current flow.FET have N-channel and P channel for conduction.FET are mainly used in analogue switch, low noise amplifier and buffer amplifier.

Types of transistor FET

Other Types

There is a lot pf transistor types which is MOSFET ,JFET ,insulated-gaye bipolar transistor, thin film transistor, Inverted-T field effect transistor, organic field –effect transistor(OFET)diffusion transistor, fast-reverse epitaxial diode field-effect transistor(FREDFET)schottky transistor, tunnel field effect transistor, high electron mobility transistor etc

Construction of BJT

BJT is three terminal device which is emitter, base and collector. It consist two PN junctions .One PN junction of BJT exist between the emitter and abase region and another PN junction exist between the collector and base region. During normal operation of BJT ,the base-emitter junction is in forward biased and base collector junction is in reversed biased. There are two type of BJT one is NPN transistor and second is PNP transistor .

types of transistor
types of transistor BJT

Working Of Transistor

Let discuss the working of NPN transistor. The NPN emitter is made by n-type material, therefore the majority carriers are electron in n-type material. When we connected the base-emitter junction in forward biased then the electron will move from n-type region toward p- type region and minority carrier holes move toward the n-type region. As a result of meeting these holes and electrons ,the current will flow across the junction. If emitter base junction is connected in reverse biased then the holes and electrons move away from the junction and as a result the depletion region forms between the two regions and due to this depletion region no current flow through the junction.

working of BJT

As a result of current flow between the base and emitter the electrons will leave the emitter and enter in to the base.Electron will combine when they reach at depeletion region.But we know  that the doping level of base region is very light and thin in shape therefore the most of the electron across the region without recombining with the holes and as aresult the electrons will drift toward the collector region.

When a current flows between base and emitter the electrons will leave the emitter and flow into the base as shown above. Normally the electrons will combine when they reach the depletion region.

But the doping level in this region is very low and the base is also very thin. This means that most of the electrons are able to travel across the region without recombining with holes. As a result, the electrons will drift towards the collector.

Transistor Characteristics

Transistor characteristic is the relationship between the current and voltage of transistor in the specific configuration. There are three types of characteristic.

1-Input characteristic

This characteristic tell us about the change in input current with the change in input voltage of transistor when output voltage is constant.

2-Output characteristic

It tell us the relationship between the output current and output voltage when input current is constant.

3-Current Transfer Characteristic

It tell us about the variation in output current with the input current when the voltage is constant

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