Reverse bias means that the negative region is connected to the positive terminal of the supply and p-region is connected to the positive terminal of the supply. The PNP transistor symbol shows an arrow pointing inwards from the Emitter to the Base which indicates the direction of the current flow.
Viva Differences. The majority charge carriers are electrons whereas the minority charge carriers are holes. The majority charge carriers are holes whereas the minority charge carriers are electrons. NPN transistors are made up of two layers of P material with a sandwiched layer of N. A positive voltage is given to the collector terminal to produce a current flow from the collector to the emitter.
A positive voltage is given to the emitter terminal to produce current flow from the emitter to the collector. The working principle of a NPN transistor is such that when you increase current to the base terminal, then the transistor turns ON and it conducts fully from the collector to emitter. When you decrease the current to the base terminal, the transistor turns ON less and until the current is so slow, the transistor no longer conducts across the collector to emitter and shuts OFF.
The working principle of a PNP transistor is such that when the current exists at the base terminal of the transistor, then the transistor shuts OFF. It is turned ON when there is low signal applied to the base terminal. The emitter and collector of PNP transistor are made up of p-type material and their base is made up of n-type material.
The emitter-base junction of PNP is connected in forward biased while the collector-base junction is connected in reverse bias. The emitter-base junction pushes the majority charge carrier toward the base, thus established the emitter current. The hole in the p-type material combines with the n-type material hence constitute the base current. The remaining hole reaches across the negatively biased collector-base region and collected by the collector due to which collector current develops.
Thus, complete emitter current flows through the collector circuit. The NPN transistor consists two n-type semiconductor material which is separated by a thin layer of p-type material. The collector is the thickest region and the base is the thinnest region of the NPN transistor. The emitter-base region of the transistor is in forward biasing and the collector base region is connected in reverse bias.
The voltage of the reverse bias is considerably smaller as compared to the reversed biased. The emitter-base junction is in forward biasing due to which a large number of electrons is reached to the base. This develops the emitter current. The electron in the base region combined with the holes. But the base is very thin and lightly doped, thus only small holes combined with the electrons and constitute the base current. The remaining electrons reach across the collector base region and develop the collector current.
The entire emitter current flows through the collector circuit. The key to the transistor action is lightly doped base between the heavily doped collector and emitter. Your email address will not be published. Save my name, email, and website in this browser for the next time I comment. Skip to content One of the major difference between the NPN and PNP transistor is that in the NPN transistor the current flow between collector to emitter when the positive supply is given to the base, whereas in PNP transistor the charge carrier flows from the emitter to collector when negative supply is given to the base.
The symbol of the NPN and the PNP transistor are almost same the only difference between them is the direction of the arrow which is based on the emitter. In NPN transistor, the current flow from collector to emitter because positive supply is given to the base, whereas, in PNP transistor the current flows from the emitter to the collector.
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