![]() Also, the voltage provided to the collector of NPN transistor is positive and to that of PNP is negative. As the voltage provided to the emitter of NPN transistor is negative and to that of PNP transistor is positive. Also, the two types of BJT shows variation with respect to their biasing arrangement.So, their movement in NPN transistor generates high conduction. This is so because electrons are more mobile than holes. The conductivity level of NPN transistor is somewhat high as compared to PNP transistor.In NPN transistor holes are the minority carriers while in PNP transistor electrons are the minority carriers.An npn transistor exhibits faster frequency response as compared to a pnp transistor.However, the symbolic representation of PNP transistor an inward arrow from emitter towards base shows the direction of flow of current. In the symbolic representation of NPN transistor, an outward arrow from the base towards emitter represents the direction of flow of current.As against, in PNP transistors, the current flows from emitter to collector terminal. In NPN transistors, the current flows from collector to emitter terminal i.e., opposite to the direction of movement of electrons.While in PNP transistor due to sandwiching of the n region between two p regions holes acts as majority carriers. The factor that generates a key difference between NPN and PNP transistor is that in NPN transistor due to sandwiching of p region between two n regions electrons are the majority carriers.Key Differences Between NPN and PNP Transistor While the collector is doped at a moderate level but it has the greatest size among all the regions. Here also, among the 3 regions, the emitter is highly doped but has moderate in size. Thus, in this way, current flows from emitter to collector i.e., in the direction of the movement of holes. Also, the collector region is connected to the negative terminal of the battery, hence the negative terminal attracts holes drifting towards the collector region. While the base is lightly doped hence very small amount of moving holes gets combined with the electrons of the base region. These holes on experiencing repulsive force move towards the lightly doped base region. Thus, the positive potential of the battery applies repulsion to the holes present in the p region. Here, holes acts as majority carriers and electrons are the minority carriers.Īs the forward voltage is provided at the emitter-base junction of the transistor. In PNP transistor, n region is sandwiched between two p regions. The figure below represents the PNP transistor with biasing arrangement: It also consists of an emitter, base and collector region. PNP is the abbreviation used for the positive-negative-positive transistor. ![]() On the other side, the base region has the smallest area and is lightly doped. While the emitter region is the second-largest but is highly doped. Thus, in this way current flows from collector to emitter i.e., in the reverse direction of the movement of electrons.Īmong the 3 regions, the collector region has a larger area but it is moderately doped. Hence, this positive potential attracts electrons from the base region. Rest move towards the collector region, and as we can see clearly in the above figure, that collector region is connected with the positive terminal of the battery. And on reaching the base region only a few electrons get combined with the holes present in that region. The applied forward biased voltage at the emitter-base junction allows the electrons to move into the base region after overcoming the barrier potential at the EB junction.Īs the negative terminal of the battery connected to the n region applies a repulsive force to the electrons present in the n region. In NPN transistor, electrons are the majority carriers and holes are the minority carriers. In an NPN transistor, p-region is sandwiched between two n regions. Here, the leftmost n region shows the emitter region, the middle p region shows the base region and the rightmost n region shows the collector region. The figure below represents the NPN transistor with biasing arrangement: It is a 3-layer device namely emitter, base and collector. NPN is the abbreviation used for Negative-Positive-Negative transistor. Let’s see the contents to be discussed under this article and then we will move further in order to understand other major differences between the two.
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