# Region of Operation of BJT

Discussion in 'Electronics Homework Help' started by BigBen10, Dec 19, 2012.

1. ### BigBen10

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Nov 11, 2012
My lecturer has bn teasing us with this. In what region of operation will a BJT be operating when Vbe=0? i.e the emitter and base are shorted.Thanks 4 ur replies

2. ### (*steve*)¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥdModerator

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Jan 21, 2010
How many regions of operation are there and what are they?

What defines these?

The correct answer will be clear.

3. ### BigBen10

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Nov 11, 2012
There are four regions. Forward active when Vbe>0 and Vbc<0, Reverse active when Vbe<0 and Vbc>0, Saturation when Vbe>0 and Vbc>0 and Cutoff when Vbe<0 adn Vbc<0.The above is for NPN. The question is a PNP BJT with Veb=0v and Vcb=-3v. The problem is non of the values Vbe's above a definite value(=0), they either greater than or less than.

4. ### (*steve*)¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥdModerator

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Jan 21, 2010
Perhaps you should read the wikipedia entry for this:

http://en.wikipedia.org/wiki/Bipolar_junction_transistor#Regions_of_operation

The regions are not as clear-cut as you might imagine and you might want to read what it says specifically about operation close to where the be junction goes from forward to reverse bias.

edit: if you look at it in terms of be current, it will also be clearer.