about transistor operation

[padmanaban_surya]

Anyone please post why NPN transistor is preffered than PNP transistor..?????????

 

[hshah8970]

The mobility of electrons (carriers in N region) is greater than the mobility of holes (carriers in P region) which makes NPN transistors faster than PNP ones.

 

[dlhylton]

NPN Transistors have more of the desired action that is wanted. NPN Transistors are normally off and turn on when the base current is sufficient to turn it on. PNP transistors are normally on and shut off when voltage is supplied to it. Thus, NPN transistors mimic more of the action that is wanted in circuits.

 

[godfreyl]

PNP transistors are normally on and shut off when voltage is supplied to it.

No. PNP transistors work the same as NPN transistors, but with reverse polarity.

 

[ZekeR]

hshah8970 gave an excellent explanation, while dlhylton ... well, you have much to learn.

The conductive action that turns a bipolar transistor "on" is the presence of minority charge carriers in the base region, which are drawn in by the base-emitter potential due to the emitter's high doping concentration. (The emitter "emits" charge carriers into the base, which are mostly swept up by the collector before they have time to recombine in the base). In an NPN transistor, the charge carriers happen to be electrons which have high "mobility" (i.e., they move fast) while the charge carriers in PNP transistors are holes, which have lower mobility. So, for a given cost, NPN transistors simply conduct more than PNP's.

 

[goldsmith]

Hi all
Yes i'm agree , about this statement that PNP is slower than NPN . and , i think another reason is that making an NPN transistor is simpler .
Best Wishes
Goldsmith