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Can we make a transistor with two diodes for use as fully functional transistor if yes then how if no then why?
You just can’t. There’s a transistor-model which is explained with two diodes and you can measure the two diodes in the transistor but you cannot make a transistor with two diodes. The assymetrical doping of collector and emitter and the very thin shared base differs the real transistor from your diodes.
Can two pn junction diodes placed back to back work as PNP transistor?
No, because in this case n-region will be too thick and so most of the majority charge carriers rushing from emitter to collector will be neutralized in the base. As a result the transistor will not work.
Why a BJT can not be replaced with two pn junctions connected back to back?
Summary: Two back-to-back PN diodes can’t function as a single BJT because transistor’s functionality requires semiconductor only Base region. Once a metal introduced in this path (which is what two back-to-back diodes represent) , no BJT functionality is possible.
Why are two diodes not the same as a transistor?
That’s why we can never form a transistor by using two diodes back to back. diode and diode back to back is not same a transistor, because the base with is too large. Back to back diodes have not only np and pn janctions but p to contact and contact to p junctions too.
Why are two back to back diodes not a BJT?
Two back-to-back PN diodes can’t function as a single BJT because transistor’s functionality requires semiconductor only Base region. Once a metal introduced in this path (which is what two back-to-back diodes represent) , no BJT functionality is possible. No. Two back to back diodes is NOT a transistor.
Can a transistor be connected back to back?
Although, it is said that a transistor is a device in which two PN junction diodes are connected back-to-back. But, it doesn’t mean that two discrete diodes connected back-to-back can act as a transistor. In case of two discrete diodes connected back-to-back, these have equally doped regions. So that the overall circuit has 4 equally doped regions.
What happens if we combine two PN diodes back to back together?
Let’s start with developing a very simplistic view: Two diodes as you mentioned, connected back to back, with the inner electrode only connected to the two n-type areas. assume these diodes are close to ideal, they conduct current with nearly zero voltage drop in forward direction, and block current in reverse direction.