Difference between bipolar junction transistor (BJT) & field effect transistor (FET)

BJT and FET are electronic devices.The basic difference between BJT and FET is that bipolar junction transistor is the bipolar and current control device,while FET (field effect transistor) is the uni junction transistor.It is a voltage control device.

The Difference between bjt and fet

                           BJT                                 FET
1:BJT (bipolar junction transistor ) is the bipolar device.1:FET (field effect transistor) is a uni junction transistor.
2:Its operation depends on both majority charge carriers and minority charge carriers.2:Its operation depends on majority charge carriers which may be holes or electrons.
3:Input impedance of bjt is very less i.e (1k -3k)3:Input impedance of FET is very large.
4:It is the current control device.4:It is the voltage controlled device.
5:It is more noisy.5:It is less noisy.
6:Its frequency variations effect its performance.6:It has high frequency response.
7:It is temperature dependent device.7:It has better heat stability.
8:It is cheaper.8:It is costly than bjt.
9:It is bigger in size than FET.9:It is smaller in size than BJT.
10:It has an offset voltage.10:It has no offset voltage.
11:It has more gain.11:It has less gain.
12:It has high output impedance because of high gain.12:It has low output impedance because of less gain.
13:Its collector and base are more positive than emitter.13:Its Drain is positive,gate is negative w.r.t to source.
14:Its base is negative w.r.t to emitter.14:Its gate is more negative w.r.t to source.
15:Bjt has three parts ( base ,Emitter and Collector).15:Fet has three parts (Drain,Source and Gate).
16:It has high voltage gain.16:It has low voltage gain.
17:It has low current gain.17:It has high current gain.
18:Its switching time is medium.18:Its switching time is fast.
19:It is easily biased. 19:Its biasing is difficult.
20:These are preferred for low current applications.20:These are preferred for low voltage applications.
21:It requires small amount of current to keep on.21:They requires small amount of voltage to keep on.
22:It consumes more power.
23:It has negative temperature co efficient.
22:It consumes less power.
23 :It has positive temperature co efficient.



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