Difference between FET and BJT



(1) FET stands for field effect transistors

(2) FET is an unipolar device means current flow is due to majority carriers only

(3) It is a voltage controlled device                          

(4) FET has very high input impedance, in order of mega ohm (MΩ)

(5) Less noise than BJT                                               

(6) FET has no offset voltage at zero drain current , hence makes an excellent signal chopper 

(7) They are more temperature stable than  BJT                                                                               

(8) Simple to fabricate and required less space in IC                                                

(9) FET has fast switching time in compare than BJT    

(10) Mostly FET has low voltage gain and very high current gain

(11) FET are three terminal devices name as source(S) , Gate (G) , Drain(D)                          

(12) FET have less value of Gain and Bandwidth product                                               

        Gain×Bandwidth  = Less value                               

(13) Characteristics curve of FET

charactristics curve for FET                         

(14) Symbol for FET representation




(1) BJT stands for bipolar junction transistors 

(2) BJT is a bipolar device means current flow is due to flow of majority carriers as well as flow of                    minority carriers

(3) It is a current controlled device 

(4) BJT has low input impedance compare to FET

(5) They have more noise due to minority carriers 

(6) They can not makes an excellent signal chopper 

(7) They are less temperature stable due to leakage current and reverse saturation current

(8) BJT fabrication is not very simple and required more space in IC

(9) They have less switching time in compare to FET

(10) They have high voltage gain and low current gain

(11) BJT are three terminal device name as Emitter(E), Base(B), Collector (C)

(12) BJT have very high value of Gain and Bandwidth product 

         Gain×Bandwidth = High value

 (13) Characteristics curve of BJT


charactristics curve for BJT

(14) Symbol for BJT representation