Question

Why NPN transistor in CC mode has collector base junction forward biased ?

Answer 1

In tat slide cc mode is given as home work ,moreover i know how the BJT works but i have doubt oly in CC mode so oly i posted this question .....

Answer 2

@FrancisClinton

http://230nsc1.phy-astr.gsu.edu/hbase/electronic/npncc.html#c3
in this configuration the base (P-type) is at a lower voltage than the collector (of N-type), so the collector-base junction is reverse biased

Answer 3

collector base junction is not forward biased ,see some foreign author books...

Answer 4

@FrancisClinton
sorry, but I can't understand if you are asserting that collector-base junction is forward biased (your first question over here: "Why NPN transistor in CC mode has collector base junction forward biased ?") or reverse biased, as in your last post over here ( "collector base junction is not forward biased ,see some foreign author books...").

Answer 5

Sorry , instead of telling cc mode is not reverse biased i wrote tat cc mode is not forward biased , any way wat u said in previous comment tat cc mode has clloaector base junction reverse biased is wrong so oly i told u to refer some foreign author books.

Answer 6

@FrancisClinton

Did you check here ?
http://230nsc1.phy-astr.gsu.edu/hbase/electronic/npncc.html#c3
it's only one example.
May be you would consider these other references:
Lec_9_CCandCBDesigns_08.pdf , page 7 (Multisim bias check)
Chapter_6.pdf , printed page 433, pdf page 65 (PSice computer simulation)
ccamp.pdf , page 1, (DC solution, point D )

Answer 7

They are all about CE amplifier my question is why transistor in CC mode has collector base junction forward biased ? go to the below link and see how is connected and explain me why it is connected like tat ....
http://2.bp.blogspot.com/-z08VCoweVdU/TmjU7MASIRI/AAAAAAAAB_M/jNaKhFVKCRA/s1600/untitled.JPG

Answer 8

Sorry FrancisClinton, but this my last attempt to be more clear.
All references I gave you just above (at the proper pages) are about Common Collector amplifiers, not Common Emitter amplifier; the last document, in particular, is only about Common Collector amplifier.
At this point I don't know if you even read them.
As for your pictures, at first glance, in the 2nd circuit (PNP type) the output is always equal to Vcc.

Answer 9

amplification can occur only if transistor is in active region...i.e emitter port should be in forwrd biasig and collector port should be reverse biased....this is appplicable in all bjt,no matter it is cc,ce.or cb..

Answer 10

how is connected and explain me why it is connected like tat ....
http://2.bp.blogspot.com/-z08VCoweVdU/TmjU7MASIRI/AAAAAAAAB_M/jNaKhFVKCRA/s1600/untitled.JPG

Answer 11

Dear FrancisClinton,
I'll try to enter in this long story (probably saying the same things of nick67 and pkjha3105, but using only different words).
CC,CB and CE use the "same" BJT as an AMPLIFIER, i.e. BJT MUST WORK in ITS ACTIVE REGION (BE junction forward biased and BC junction reverse biased). The stage of an amplifier with a BJT use the transistor terminal for input-output trasfer of signal. For example, if you want a follower (CC) input signal reaches the base whereas output signal comes from emitter.This stage has some benefits (high input impedance, low output impedance, current gain) and drawbacks (offset of hundreds of mV which strongly depends on temperature, to say the most important).
Anyway, the foudamental thing is: BE forward and BC reverse biased.
In the circuits you gave I see:
- input to the BASE
- output to the COLLECTOR
so I can think that for the BJT the EMITTER is the common terminal.
IF THE BJT WORKED IN THE ACTIVE REGION THE STAGE WOULD BE A COMMON EMITTER!
But, VBB bias maintain BC junction forward biased, so you can immediately exclude that the figure refers to an amplifier.
About CC you can surely refer to the references nick67 reported.

Answer 12

Thanks for ur explaination (stefo) now i understood it, sorry to nick67

Answer 13

thank to you for the opportunity