Bipolar Junction Transistor is a very important device of Electronics World. During second world war when world was busy in destroying humanity three great personalities were busy on inventing something new . Those guys are William Shockley,Bargain and Bardeen. They had invented something which is known as Bipolar Junction Transistor in the electronics world.
Bipolar Junction Transistor (refered as BJT) is a current control device having low input resistance below 100 ohm.
IT has very high power dissipation.
As name suggest it is bipolar device having majority and minority carrier.
Due to the presence of minority carrier it becomes a noisy device.
As compare to FET it has larger gain but gain bandwidth product is constant.
Gain bandwidth product of BJT is greater than that of FET.
It has two junction-1)Emitter Junction
2)Collector Junction
Transistor means transfer of Resistors.
It is made with Emitter,Base and collector.
Emitter is highly doped compared to base and collector.
Collector is moderately doped.
Base is lightly doped.
Base width is least among three.
Collector width is highest so that heat in collector reagon can be beard.
All three currents Ic,In,Ie are diffusion currents.
Minority currents are drift current.
Transistor works in 4 mode as per biasing-
1)Cutoff Mode
2)Active Mode
3)Saturation Mode
4) Reverse active mode.
All modes are used in digital electronics.
Cutoff mode and saturation mode is used as switch.
CutOff mode used as open switch while saturation mode used as closed switch.
Amplification is the main property why BJT is used in large which is due to Active Mode.
Refers saturation Mode is never used .
There are three type of biasing-
1) Common Emitter
2) Common Collector
3) Common Base
Common emitter is used in very low frequency or audio frequency amplification.
Common collector is also called emitter follower it is use as buffer having high input impedence.
Common base is used in high frequency or in radio frequency application. It is also used as current buffer having high output resistance and small input impedence.
Conductivity of base region is very small. SO that it can reduce the recombination in base reason.
Early effect can be find in BJT by increasing the collector base voltage (Vcb).
Bipolar Junction Transistor (refered as BJT) is a current control device having low input resistance below 100 ohm.
IT has very high power dissipation.
As name suggest it is bipolar device having majority and minority carrier.
Due to the presence of minority carrier it becomes a noisy device.
As compare to FET it has larger gain but gain bandwidth product is constant.
Gain bandwidth product of BJT is greater than that of FET.
It has two junction-1)Emitter Junction
2)Collector Junction
Transistor means transfer of Resistors.
It is made with Emitter,Base and collector.
Emitter is highly doped compared to base and collector.
Collector is moderately doped.
Base is lightly doped.
Base width is least among three.
Collector width is highest so that heat in collector reagon can be beard.
All three currents Ic,In,Ie are diffusion currents.
Minority currents are drift current.
Transistor works in 4 mode as per biasing-
1)Cutoff Mode
2)Active Mode
3)Saturation Mode
4) Reverse active mode.
All modes are used in digital electronics.
Cutoff mode and saturation mode is used as switch.
CutOff mode used as open switch while saturation mode used as closed switch.
Amplification is the main property why BJT is used in large which is due to Active Mode.
Refers saturation Mode is never used .
There are three type of biasing-
1) Common Emitter
2) Common Collector
3) Common Base
Common emitter is used in very low frequency or audio frequency amplification.
Common collector is also called emitter follower it is use as buffer having high input impedence.
Common base is used in high frequency or in radio frequency application. It is also used as current buffer having high output resistance and small input impedence.
Conductivity of base region is very small. SO that it can reduce the recombination in base reason.
Early effect can be find in BJT by increasing the collector base voltage (Vcb).
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